D I R E C T I O N S I N D E V E L O P M E N T 34518 The Niger River Basin AVision for Sustainable Management INGER ANDERSEN, OUSMANE DIONE, MARTHA JAROSEWICH-HOLDER, JEAN-CLAUDE OLIVRY EDITED BY KATHERIN GEORGE GOLITZEN BENIN The Niger River Basin: A Vision for Sustainable Management The Niger River Basin: A Vision for Sustainable Management Inger Andersen Ousmane Dione Martha Jarosewich-Holder Jean-Claude Olivry Edited by Katherin George Golitzen THE WORLD BANK Washington, DC © 2005 The International Bank for Reconstruction and Development / The World Bank 1818 H Street, NW Washington, DC 20433 Telephone: 202-473-1000 Internet: www.worldbank.org E-mail: feedback@worldbank.org All rights reserved. 1 2 3 4 08 07 06 05 The findings, interpretations, and conclusions expressed in this paper do not necessarily reflect the views of the Executive Directors of The World Bank or the governments they represent. The World Bank does not guarantee the accuracy of the data included in this work. 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All other queries on rights and licenses, including subsidiary rights, should be addressed to the Office of the Publisher, The World Bank, 1818 H Street, NW, Washington, DC 20433, USA; fax: 202-522-2422; e-mail: pubrights@worldbank.org. ISBN-10: 0-8213-6203-8 ISBN-13: 978-0-8213-6203-7 e-ISBN: 0-8213-6204-6 DOI: 10.1596/978-0-8213-6203-7 Library of Congress Cataloging-in-Publication Data has been applied for. Contents Foreword vii Acknowledgments ix Executive Summary x Acronyms and Abbreviations xv 1 Overview of Niger River Basin Countries and Basin History 1 The Countries of the Niger River Basin 4 History of the Basin 7 2 The Physical Geography of the Niger River Basin 11 Physical Environment and Hydrography 11 Navigable River Segments 19 Geology and Hydrogeology 20 Soils 22 Natural Environment 24 Climatic Conditions 25 Climate and Water Resources Variability 27 3 The Niger River Basin's Water Resources 30 Hydrology 30 Transport of Suspended and Dissolved Solids 48 Water Quality 56 Closing Comments on the Technical Chapters 57 4 Cooperative Development of the Niger River Basin: Criteria for Success 58 Promoting Development and Poverty Reduction 58 From Unilateral to Cooperative Development 59 Laying the Institutional Foundation for Cooperation 60 v vi CONTENTS A Political Mandate: The Shared Vision and Sustainable Development Action Program 63 Making Cooperation Happen in the Niger River Basin 63 People and the Environment: A Focus of Cooperation 65 Criteria for Success and Ways Forward 68 Appendixes 70 Appendix 1: Main Maps of the Niger River Basin 70 Appendix 2: Technical Supporting Information 86 Appendix 3: Overview of Data Management 127 Appendix 4: Glossary 129 Endnotes 131 Bibliography 132 Index 141 Foreword The Niger River Basin, home to approximately 100 million people, is a vital, complex asset for West and Central Africa. It is the continent's third longest river (4,200 kilometers), traversing nine countries--Benin, Burkina Faso, Cameroon, Chad, Côte d'Ivoire, Guinea, Mali, Niger, and Nigeria. The Niger River embodies the livelihoods and geopolitics of the nations it crosses. This river is not simply water, but is also an origin of identity, a route for migration and commerce, a source of potential conflict, and a catalyst for cooperation. As the regional population and economies grow, this life-giving resource will require integrated water resources management to address sustainably the increasing aspirations and needs of the people of the Basin. Regional cooperation among the nations sharing the Basin is crucial to optimizing sustainable economic development while ensuring environ- mentally sound management. Over previous decades, the Niger River Basin countries have focused more on unilateral water resources develop- ment than on the potential benefits of cooperation. Recently, however, the Basin countries have renewed their commitment to address sustainable management and development of the Basin's resources through an improved framework and a Shared Vision process. In doing so, they are setting an important path for cooperative water resources planning, management, and development that could serve as a model for water resources management for Africa's many shared rivers. From the Guinea highlands, through the Office du Niger in the Inland Delta, to the Niger Delta, the greatest opportunities will come from managing efficiently the water resources on which millions of people depend for their livelihoods, taking into consideration the range of demands, associated infrastructures, and ecological complexity. As in all river basins, different groups of users have conflicting priorities and preferences. Thus, it is important to understand how the river and its resources are used in order to avoid conflict and promote cooperation. This overview of the potential of the Niger River's water resources discusses the hydrographic system--the river and its tributaries, hydrology, vii viii FOREWORD climate, and water quality and use. It attempts to capture the full spectrum of the Niger ecosystem's values and benefits and to support the integra- tion of science and decision making, and, as such, can serve as a tool for transboundary cooperative management of shared water resources. The final chapter discusses the criteria for success that will be required to broker agreement for the cooperative development and management of the river. The book is presented as a contribution to support and foster the Shared Vision process for integrated management and development of this majestic river, for the benefit of the people of the Niger River Basin. Michel Wormser Sector Director Private Sector and Infrastructure Africa Region Acknowledgments This book intends to contribute to the Niger River Basin Shared Vision process. Having devoted much of his academic career to the study of the Niger River, Jean-Claude Olivry has produced an extensive study, based on his own research and a compilation of existing information. The study by Jean-Claude Olivry forms the background for this book. Drawing from his work, a team comprising Ousmane Dione, Martha Jarosewich-Holder, and Katherin Golitzen prepared chapters 1­3. The concluding chapter has been written by Inger Andersen (Director, Water, Environment, Social and Rural Development Unit, Middle East and North Africa Region), with input from the World Bank team, and provides a discussion of the criteria for suc- cess in water resources development in the Basin. The team would like to thank the Niger Basin Authority for its cooper- ation and support, namely Mohammed Bello Tuga (Executive Secretary), Ousmane Diallo (Environmental Specialist), Oumar Ould Ali (Chief Hydrologist), Robert Dessoussi (Hydrologist), and the Niger Basin Authority Focal Points within the nine member countries. The team also extends its thanks for reviews, input, suggestions, and comments received from Johan Grijsen, Amal Talbi, Esther Monier-Illouz, and cartographer Jeff Lecksell. The team is grateful for the technical input and peer review of Alessandro Palmieri, Lead Dam Specialist, Environmentally and Socially Sustainable Development Network, World Bank. In addition, the team has benefited greatly from advice and guidance provided by David Grey, Senior Water Adviser, Africa Region, World Bank. Finally, the team expresses its appre- ciation to the government of the Netherlands for funding the translation and publication through a grant from the Bank-Netherlands Water Partnership Program. ix Executive Summary This book comprises two distinct elements. The first, and major, part of the book (chapters 1­3) is a unique and essential compilation of technical infor- mation and data on the entire Niger River system. It presents a compre- hensive overview of the physical environment and hydrological functions of the watershed, thus providing the necessary background for examina- tion of the challenges of resource management and development potential. The second part of the book (chapter 4) presents the fundamental challenges that the nine countries1 of the Basin face and are now addressing. Introduction The river is described in the first three chapters as a single hydrologic system, yet it has largely been developed unilaterally, in spite of the existence of a convention and a river basin organization. Chapter 4 presents a descrip- tion of the path that the political leaders of the Basin have chosen to take and a discussion of what is needed to achieve their goals. It is the combi- nation of these elements--the hydrology and geography of the river system with the economic opportunities, institutions, politics, and diplomacy-- that is essential to achieve joint and optimal development of this shared resource. The Niger River Basin, host to approximately 100 million people, is a large catchment area with significant water resources development poten- tial. Effective development presupposes international and bilateral agree- ments, together with national commitment to sustainable use of shared resources. Such commitment is particularly important given that the many variations in geography, culture, demographics, and economics among the Basin countries lead to differing needs and expectations with regard to the Basin's resources. Coordination and cooperation among decision makers and users is crucial to address the threats to water resources from natural causes and human activities. The Niger Basin Authority (NBA) is mandated to foster this cooperation and sharing of resources at the national and regional levels. The NBA brings together the Basin countries to understand the x EXECUTIVE SUMMARY xi complex interrelated dynamics of the Niger River Basin and to promote integrated water resources management. To this end, the Basin countries have agreed that the Niger Basin Shared Vision will be implemented through a Sustainable Development Action Program (SDAP). Through a multidisciplinary dialogue, the SDAP will con- tribute to building the institutional capacity, policy harmonization, and public support that will create the framework for enhanced cooperation among the Basin countries. Overview of Niger River Basin Countries and Basin History The Niger River Basin is an extraordinary asset for the nine countries that are within its watershed and for the broader West and Central Africa region. Each country within the Basin has unique geographic settings and a wide range of available resources. Chapter 1 summarizes country geographic settings and socioeconomic characteristics. The countries can be clustered as "water resources producers"--Guinea, Cameroon, and to a lesser extent Benin; or "water resources consumers"--Mali and Niger. Nigeria is both a producer and a consumer. Côte d'Ivoire, Burkina Faso, and Chad are part of the Basin but are minimally affected by the use and management of the river's water resources. Historical water resources use, from sustenance to commerce, has influ- enced the evolution of development and cooperation in the region. The European colonial legacy of exploration and expansion was followed by the independence movement in the 1960s, in which an initial effort was made to define the conditions for shared development of the Basin. These efforts evolved over 20 years, and in 1980, the present NBA replaced the Niger River Commission. The evolution of the NBA has continued to the present. Its leadership has a clear commitment to the integrated manage- ment of the Basin's environmental and water resources. Physical Geography of the Niger River Basin The Niger River is Africa's third longest river (4,200 kilometers) and encom- passes six hydrographic regions, each of which is distinguished by unique topographic and drainage characteristics. The Upper Niger River Basin headwaters are in the Fouta Djallon Massif, Guinea. From there the river flows northeast, traversing the Inland Delta, a vast spreading floodplain (averaging 50,000 square kilometers) that dissipates an appreciable portion of its potential hydraulics through absorption and evaporation. When it reaches the fringes of the Sahara Desert, the Niger River turns back by form- ing a great bend and flowing south and east as the Middle Niger River xii EXECUTIVE SUMMARY section, then as the Lower Niger, to the Niger Delta at the Gulf of Guinea, which it reaches after being joined by its largest tributary, the Benue River. The diverse geographic and climatic characteristics of the Niger River Basin play an important role in water resources availability, which in turn affects a range of water resources­related activities. The Niger River water system is one of the most impressive examples of the influence of topogra- phy and climate on the flow conditions of a water system. Such a large basin area cannot be expected to have uniform climatic and rain patterns, and the Niger River traverses a wide range of ecosystem zones in West Africa. A combination of human population growth, unsustained resource use and development, and desertification threatens the Niger River's ability to supply crucially needed natural resources to the people of the Basin. The geology and soils of the Basin also influence groundwater availability. Significant rainwater deficits and the variable duration of the rainy season result in hydrological deficits that are not necessarily reflected in a direct response of the base flow. Chapter 2 reviews the Basin's physical geography, six hydrographic regions, geology, groundwater and soils, natural environ- ment, and climatic characteristics. The Niger River Basin's Water Resources The Basin is a unique and complex river system with an extensive network of tributaries. Using available information, chapter 3 evaluates the Basin's water resources in the six corresponding hydrologic reaches. Because of cli- matic variations, the annual river flood does not occur at the same time in different parts of the Basin. There are usually high flows from the head- waters in Guinea, a decrease in flow caused by evaporation and expansion in the floodplain of the Inland Delta, followed by an increase in flow from tributary input through the Middle and Lower reaches as the river enters the Niger Delta. In the Upper Niger, the high-water discharges generally occur in September, and the low-water season is generally April­May. The Inland Delta has an estimated storage capacity of 70 cubic kilometers but has a high rate of loss caused by evaporation over the thousands of square kilo- meters of its floodplain. This loss is estimated at about 44 percent of the inflow. The peak flow period that arrives in September is delayed as it spreads out, exiting the Inland Delta three months later. A phase of reced- ing water extends into February. In the Middle Niger, at Niamey, the max- imum flows are usually twofold: a first wet seasonal peak flow and the upstream peak flow that arrives during the dry season. The first high-water discharge, known as the white flood (because of the light sediment content of the water), occurs soon after the rainy season in September. Asecond rise, known as the black flood, begins in December with the arrival of inflow from upstream. May and June are the low-water months in the Middle Niger. EXECUTIVE SUMMARY xiii On the Benue, there is only one high-water season, because of the Benue's more southerly climatic location; this normally occurs from May to October, which is earlier than on the Middle Niger. The Lower Niger below its con- fluence with the Benue consequently has a high-water period that begins in May or June and a low-water period that is at least a month shorter than on the Middle Niger, because the rains in the south start earlier. In terms of water quality, an increase in siltation is linked to erosion, deforestation, and soil depletion. Cooperative Development of the Niger River Basin-- Criteria for Success A better understanding of the Niger River Basin will assist decision makers in basin management. It is a premise of river basin management that man- aging the river as a system yields optimal benefits. In the case of the Niger River, this could mean increased water, food, power, transport, and so on. Optimized management of any river is difficult, primarily caused by the need to recognize so many different interests. Management of an interna- tional river is particularly difficult, but much can still be done to move toward optimized management. Once cooperative investments have been made in the development of the water resources, trust and cooperation will grow between the countries and many other benefits will accrue, including those "beyond the river," such as communication investments, increases in trade, improved flows of labor, and so on, thereby leading to better regional integration of the coun- tries of the basin. Specific investment opportunities identified by the coun- tries include enhanced food and energy production; transportation; environmental management, such as investments in land productivity and measures against desertification; flood and drought management; and investments in livestock, fisheries, and tourism. The NBASummit of Heads of State has set the organization on a renewed path, through the Shared Vision process and SDAP. If the NBA is to suc- ceed in revitalizing itself so that it can drive regional development of the river, several criteria for success will be required of the institution, its stake- holders, and the donor community. These success criteria are necessary to ensure that the reengagement and renewal, which are currently taking place within the NBA, will take hold. Institutionally, the NBA will need to earn and recapture legitimacy, rele- vance, and support from its constituency. National engagement from gov- ernments and other key stakeholders--in the form of a strong champion and an adequate coordination mechanism for river basin management--is critical to moving development forward. For national water resources man- agement and development aspirations to be fulfilled by the shared water xiv EXECUTIVE SUMMARY resources, a broad national constituency must have ownership of the agenda. The degree to which the NBA can recapture both legitimacy and relevance will largely determine whether the institution will meet the expectations of its constituency. This is all the more important because NBA financial sus- tainability, which is key to its renewal and survival, will be secure only after the constituency sees the relevance and benefits from the institution. The Niger Basin Summit of Heads of State has embarked on a Shared Vision process. This is a bold commitment, moving from a past of unilat- eral actions on the river toward enhanced coordination, collaboration, and joint action. The process is an expression of the political commitment of the heads of state to a cooperative agenda. The Shared Vision will guide the formulation of the SDAP, which will identify and define the development opportunities in which the Basin countries can jointly participate. The Shared Vision and the SDAP will form a platform for mobilizing resources from the NBA countries and from the donor communities for investments to implement the SDAP. To succeed in moving this process forward, the NBA will need to con- tinue toward greater transparency, inclusivity, and engagement of the com- munities and stakeholders who live with and on the river. Issues such as escalating populations, conflict and war, and environmental stresses will continue to put increased pressure on the river and its resources. Although the NBA cannot address all these issues, the organization can be an impor- tant platform for awareness of transboundary impacts of socioeconomic pressures on natural resources. The subsidiarity principle will help the NBA, as part of the SDAP, to identify areas where the institution will have a com- parative advantage over well-established national and local agencies, which are also charged with working on these matters. The path ahead is clearly difficult. As the countries move forward, the key ingredients for success include continued strong political leadership and champions, staying the course of the reform process, maintaining a dynamic and enabled staff, and sustaining a financially viable institution that continues to stay on message, to move beyond unilateral planning, to facilitate hydrodiplomacy, and to engage donors to commit to their side of the compact. Acronyms and Abbreviations AGRHYMET Centre Régional de Formation et d'Application de la Météorologie et de l'Hydrologie Opérationnelle (Regional Center for Training and Application of Meteorology and Operational Hydrology) AOC-HYCOS Afrique de l'Ouest et Centrale (West and Central Africa) Hydrological Cycle Observing System CIDA Canadian International Development Agency CILSS Comité Permanent Inter-Etats de Lutte contre la Sécheresse au Sahel (Permanent Interstate Committee for Drought Control in the Sahel) CIP Centre Inter-Etats de Prévision (Interstate Forecasting Center) FONDAS Niger River Basin Development Fund GDP gross domestic product GNI gross national income GHENIS Gestion hydro-écologique du Niger supérieur Mali- Guinée HA hydrological areas HDI Human Development Index HYDRONIGER Hydrological Forecasting System in the Niger River Basin IRD Institut de Recherche pour le Développement (Research Institute for Development; formerly ORSTOM) JICA Japan International Cooperation Agency NBA Niger Basin Authority NOAA-AVHRR United States National Oceanic and Atmospheric Administration (Advanced Very High Resolution Radiometer) OMVS Organisation pour la Mise en Valeur du Fleure Senegal (Senegal River Basin Organization) xv xvi ACRONYMS AND ABBREVIATIONS ORSTOM Office pour la Recherche Scientifique et Technique d'Outre Mer (Office for Overseas Scientific and Technical Research; now IRD) PIRT Projet d'Inventaire des Ressources Terrestres SDAP Sustainable Development Action Program TDS total dissolved solids TOC total organic carbon Ts transport spécifique (specific transport) TSS total suspended solids UN United Nations UNDP United Nations Development Programme UNESCO United Nations Educational, Scientific, and Cultural Organization WDI World Development Indicators WHO-Oncho World Health Organization (Onchocerciasis Control Program in West Africa) WHYCOS World Hydrological Cycle Observing System WMO World Meteorological Organization 1 Overview of Niger River Basin Countries and Basin History The Niger River is shared by nine countries in West and Central Africa-- Benin, Burkina Faso, Cameroon, Chad, Côte d'Ivoire, Guinea, Mali, Niger, and Nigeria (see appendix 1, map 1). The nine Basin countries are among the poorest in the world. Four are among the bottom 20 countries on the World Development Indicators (WDI) scale,2 and seven are among the bottom 20 on the United Nations Development Programme (UNDP) Human Development Index (HDI).3 The need for development and investment in the region is evident, and the Niger River holds tremendous development potential. Development opportunities range from those directly related to the river, such as power, irrigation, and navigation, to those "beyond the river," such as increases in trade, communication investments, and enhanced labor flows. The Basin's contrasting geographic settings and variable availability of raw materials and natural resources drive local and regional development. The Niger River's hydrologically active basin covers a surface area of nearly 1.5 million square kilometers shared among the nine countries according to the following approximate percentages: Benin (2.5 percent), Burkina Faso (3.9 percent), Cameroon (4.4 percent), Chad (1.0 percent), Côte d'Ivoire (1.2 percent), Guinea (4.6 percent), Mali (30.3 percent), Niger (23.8 per- cent), and Nigeria (28.3 percent). The population living in the Basin is esti- mated at 100 million, with an average growth rate of 3 percent per year. In terms of managing and using the Niger's water resources, the nine Basin countries can be clustered as "water resources producers"--Guinea, Cameroon, and to a lesser extent Benin; or "water resources consumers"-- Mali and Niger. Nigeria is both a producer and a consumer. Côte d'Ivoire, Burkina Faso, and Chad are part of the Basin but are minimally affected by the use and management of the river's water resources. Table 1.1 sum- marizes the general statistical socioeconomic characteristics of the Niger Basin countries and their relative characteristics as part of the Basin, and describes the individual socioeconomic setting of each country. Maps 2­8 in appendix 1 illustrate the countries' geographic features and Basin characteristics. 1 Table 1.1 Socioeconomic Statistical Characteristics of the Niger River Basin Countries Burkina Côte Parameter Benin Faso Cameroon Chad d'Ivoire Guinea Mali Niger Nigeria Total area (millions km2) 0.114 0.274 0.475 1.284 0.322 0.246 1.24 1.27 0.924 Population (millions) 6.75 10.7 14.9 8.3 15.4 7.1 10.6 10.7 114 2 Population increase (%/year) 3.1 2.3 2.3 3.2 2.1 3.1 2.2 3.5 2.7 Urban population (%) 39.9 18 48.1 23.5 45.8 32.1 29.4 20.1 43.1 GDP/person (US$) 933 965 1,573 850 1,653 1,934 753 753 853 Estimated population 11.5 21.7 27.8 13.4 29.9 14 22.7 19.2 235 2025 (millions) Agricultural production (1,000 tons) Rice 36 89 65 100 1,162 750 590 54 3,400 Peanuts -- 205 160 372 144 182 140 -- 2,783 Corn 662 378 600­850 173 573 89 341 5 5,127 Millet 29 979 71 366 65 10 641 2,391 5,956 Sugar cane -- -- -- 280 -- 220 303 174 675 Cotton 150 136 75­79 103 130 16 218 -- 55 Livestock (head, millions) Beef 1.35 4.55 5.90 5.58 1.35 2.37 6.06 2.17 19.8 Sheep 0.63 6.35 3.80 2.43 1.39 0.69 6.0 4.31 20.5 Freshwater fishing (1,000 tons) 44 -- 89 6 68 103 108 6 383 Within Niger Basin Hydrologically active Area (103 km2)a 37.50 58.5 66.0 15.0 18.0 69.0 454.50 357.0 424.50 (%) 2.50 3.90 4.40 1.0 1.20 4.60 30.30 23.80 28.30 Population (millions) 1.95 2.12 4.46 0.08 0.80 1.60 7.80 8.30 67.60 (%) 2.10 2.20 4.70 0.10 0.80 1.70 8.20 8.80 71.40 Source: Data are primarily based on recent (2004) national multisector studies on the assessment of opportunities and constraints to development 3 of each country's portion of the Niger River Basin, prepared with support from the World Bank (Cameroon, Chad, Guinea, and Nigeria) and the Canadian International Development Agency (CIDA) (Benin, Burkina Faso, Côte d'Ivoire, Mali, and Niger). Note: -- not available. Values in italics relate to data involving the entire country; data in plain text relate to the part of the country located in the Niger River Basin. a. http://www.riob­info.org/gwp/PP_Niger.pdf. The hydrologically active area of the Niger River Basin is 1.5 million square kilometers. 4 THE NIGER RIVER BASIN: A VISION FOR SUSTAINABLE MANAGEMENT The Countries of the Niger River Basin Benin The catchments of several right-bank tributaries of the Middle Niger River are situated in northern Benin, occupying 2.5 percent of the total area of the Basin (37,500 square kilometers). Benin is densely populated, with 65 inhab- itants per square kilometer, on average. More than 1.95 million people live in the Niger Basin in Benin. The land within the Basin is used primarily for grazing and livestock, although there are areas, once used for groundnut farming, that are now used for cotton farming. Cotton farming in this area now contributes one-third of the national production. The main city is Kandi, and Malanville is the river port. The railroad from Cotonou reaches only to Parakou, in the center of the country, thus limiting access for commerce to Kandi. The Mekrou River, a tributary of the Niger, crosses the "W" International Park, an extensive protected sanctuary for flora and fauna, shared by Benin, Burkina Faso, and Niger. Burkina Faso Similar to Benin, several tributaries of the Niger River originate in Burkina Faso. About 25 percent (58,500 square kilometers) of the country's total ter- ritory is within the Basin, comprising about 3.9 percent of the Basin's area. One-quarter of Burkina Faso's population, 2.12 million, lives in the Basin, which is the driest region of the country. It is also the poorest economic area, with pastoral livelihoods that are seminomadic in the north and sedentary in the south. Cameroon The headwaters of the Benue River, a major tributary of the Niger River, lie within Cameroon, comprising 4.4 percent (66,000 square kilometers) of the Basin. A population of 4.46 million lives in this part of the Basin. The Benue watershed is predominantly agricultural, producing cotton and peanuts for export. Livestock is also important, especially on the Adamawa Plateau. High expectations for floodplain irrigation development have not been met, despite the construction of the Lagdo Dam. This dam was also expected to add a few additional months of navigation on the Benue, establishing Garoua as a river port through which cotton could be shipped downstream, to be traded for manufactured products and raw materials. However, continued low water flows have limited the duration of the navigation period. The potential hydropower production from the Lagdo Dam, however, is OVERVIEW OF NIGER RIVER BASIN COUNTRIES AND BASIN HISTORY 5 significantly greater than the needs of the immediate region, providing an opportunity to export electricity. Farther downstream, areas irrigated by the Bamenda and Nkambe tributaries of the Metchum River support high- altitude grazing, in addition to tea, coffee, and corn production that add to the revenues of a densely populated area. Paddy rice is grown in the low- lands. Faro, Benue, and Boubandjida national parks are protected areas that ensure the conservation of flora and fauna and protection of the headwater areas of the upper Benue River. Chad The headwaters of the Mayo tributaries lie within Chad, comprising 1.0 per- cent (15,000 square kilometers) of the Basin. A population of 80,000 lives in this part of the Basin, extending through the upper Mayo Kebi and Kabia tributaries and the lakes of the Toubouris depression. The Basin supports a sparsely settled rural population that depends on subsistence farming and limited cotton production for its livelihood. Côte d'Ivoire The headwaters of the Bagoé, the Kankelaba, and the Baoulé tributaries lie within Côte d'Ivoire, comprising 1.2 percent (18,000 square kilometers) of the Basin. A population of 800,000 lives in this part of the Basin. The area is a southern extension of the cotton-growing areas of Mali. It also pro- duces kola nuts and is, above all, an area for raising livestock and a route for transporting cattle herds to the coast and to Abidjan. Locally, small development projects (ponds and small dams) provide opportunities for market gardening and aquaculture. The main cities are Odienne and Boundiali. Guinea The Guinea highlands (Haute Guinée) and part of the high plateaus of Guinée Forestière are two geographic provinces in Guinea situated at the headwaters of the Niger River and its tributaries, comprising 4.6 percent (69,000 square kilometers) of the Basin. About 1.6 million people live in this part of the Basin, more than 80 percent of whom live in rural areas, with a density of fewer than 30 inhabitants per square kilometer. The alluvial val- leys of these two provinces are fertile, yielding most of the country's agri- cultural production. The highlands and plateaus have fewer than five inhabitants per square kilometer, and are dedicated to raising livestock and 6 THE NIGER RIVER BASIN: A VISION FOR SUSTAINABLE MANAGEMENT limited rainfed farming, generally of sorghum and millet. Rainfall is sufficient for groundnut production in the Tinkisso watershed (about 60,000 tons per year, which is about one-third of the production in Guinea), and paddy rice production in the valleys of the Niger, the Niandan, and the Milo Rivers (estimated at 300,000 tons per year). Coffee is also grown (20,000 tons per year) on the mountain ridges and in the upper Milo River region. These two geographic provinces are rich in diamonds. Bauxite deposits are mined on the Tinkisso and gold is mined close to Siguiri. Mali The longest reach of the Niger River (1,700 kilometers) extends through southern Mali, comprising 30.3 percent of the Basin (454,500 square kilo- meters). A population of 7.8 million lives in the Basin, with a large per- centage living in the capital, Bamako, that is situated on the river. This city, with its industrial and suburban areas and its market gardens, plays a sig- nificant role in the economic development in this part of the Basin. The Office du Niger, one of the largest and oldest irrigation schemes in West Africa, continues to provide opportunities for agricultural development. Irrigated farming along the river produces 590,000 tons of rice and 303,000 tons of sugar cane per year. The Inland Delta is an undeveloped, flooded ecosystem with abundant freshwater fishing areas, high produc- tivity pastureland, and fertile agricultural lands. Catches from freshwater fishing average about 108,000 tons per year, with an additional 10,000 tons harvested on the Selingue reservoir, depending on the water level and flood- ing in the Inland Delta. Its excellent pastureland makes the Inland Delta a grazing area for more than 2 million head of cattle. Cotton production covers an area of 122,000 square kilometers. On a yearly basis, Mali produces 400,000 tons of cottonseed and 218,000 tons of cotton fiber, surpassing Egypt as the largest producer in Africa. Whereas it is an irrigated crop in Egypt, it is a rainfed crop in Mali. Southern Mali also produces more than 230,000 tons of millet and sorghum, 215,000 tons of corn, and 18,000 tons of ground- nuts per year, all as rainfed crops. Niger The river's reach through Niger is 540 kilometers, with a hydrologically active area of approximately 357,000 square kilometers occupying propor- tionally 23.8 percent of the Basin, with a population of 8.3 million. This area extends through the Maradi region, which is part of the Sokoto watershed. The left-bank tributary network, originating in the Aïr and the Azaouâk Mountains, is characterized by intermittent flows that are isolated from the OVERVIEW OF NIGER RIVER BASIN COUNTRIES AND BASIN HISTORY 7 Niger River without any hydrologic connection to the river network. The Niger River partially irrigates large alluvial plains and lowlands of the Dallol Bosso, the Dallol Maouri, and the Maradi area. Rice production is low, but production of traditional grains of the Sahel region, although sub- ject to climate variations, is significant (more than 2.4 million tons). In many places, black-eyed peas have replaced groundnuts as an export crop and cotton is no longer grown. Agricultural practices have undergone significant changes since the severe droughts of the past several decades. Niger is dependent on the navigable waterways of the Niger River through Nigeria. Nigeria Nigeria is the final downstream country through which the Niger River flows, and contains 28.3 percent (424,500 square kilometers) of the Basin area. The Niger Basin extends across 20 of the 36 states of Nigeria and com- prises two main rivers, the Niger and the Benue, and 20 tributaries. Of Nigeria's major rivers, more than half are in the Niger River Basin. Their combined length accounts for almost 60 percent of the total length of all important rivers in Nigeria. Almost 60 percent of Nigeria's population, or about 67.6 million inhabitants, live in the Basin. These Nigerians comprise 80 percent of the population of the entire Basin. Given Nigeria's size and location, its agricultural production, both rainfed and irrigated, is substantial (see table 1.1). Nigeria is also the largest oil-producing country on the African continent and the sixth largest in the world. History of the Basin A brief look at the history of the Niger River and the Basin provides an understanding of its present-day role in Central and West Africa. Throughout history, the river has played an essential role in the lives of the people who depend on it for their livelihoods. Historical Use The Niger River's original name, egerou n-igereou (river of rivers), was given by the Tuareg people to express the exceptional character they attributed to it. Over the centuries, the Niger River and its tributaries have been vital to those who lived along the river or used it for travel and trade. For travelers coming from the Sahara, the appearance of the Inland Delta as the sea of fresh water was a welcome relief. Riverbank sediment was used to make mud bricks for homes. Men and boys fished on the river daily, individually 8 THE NIGER RIVER BASIN: A VISION FOR SUSTAINABLE MANAGEMENT or as part of groups in the Inland Delta organized by and under the super- vision of the Maître des Eaux (Master of the Waters) who determined what was to be done on the river, and where and how it was to be done, accord- ing to the flood level, especially during flood recession. The sequence of flooding in the Basin allowed for flow-recession agriculture after the flood season and dry cropping along the banks and in the marshes. With regard to commerce, large Nigerien fishing vessels brought agricultural products from the south to Timbuktu and returned with salt, which came from the Sahara by camel caravan from Taoudenni. Travel on the river linked com- munities of the Basin. Precolonial armies and, later, the colonial military fol- lowed the travel routes taken by early travelers and merchants. From the 11th century, four great nations dominated in the vast grass- lands and highlands of the Basin in West Africa, trading in gold and salt: the empires of Ghana (11th­13th centuries), Mali (13th­15th centuries), Songhai (14th­16th centuries), and Kamen­Borno (16th­17th centuries). In the coastal areas, there were two prominent kingdoms: the Kingdom of Yoruba (12th­14th centuries) and the Kingdom of Benin (15th­17th cen- turies). During the 16th and 17th centuries, trade with Europeans increased along the West African coast, leading to European domination and colo- nization in the region. In appendix 1, map 9 is a historical map depicting the knowledge of the Niger Basin in 1830. Colonial Era The first agreements signed by the colonial powers regarding the Niger River region concerned the division of territory among France, Germany, and Great Britain.4 The initial treaty among the three powers, signed at the Conference of Berlin on February 26, 1885, proclaimed complete freedom of navigation and commerce based on equality among the colonial powers. Germany used the Benue to reach northern Cameroon; navigation on the Middle Niger had not yet been developed. Other treaties on commerce were also enacted during this period, such as the General Act and Declaration of Brussels in 1890. With the Franco-German treaty of 1911, France ceded to Germany the territories to the east and south of the colony of Cameroon and, notably, the eastern part of the Benue watershed (formerly Mayo Kebi), now in Chad. After Germany's defeat in World War I, the Agreement of Saint-Germain-en-Laye, signed on September 10, 1919, was an order by the League of Nations handing over the former German colony of Cameroon to France and England, and renewing the provisions con- cerning navigation on the Niger and the Benue. No further changes in colo- nial borders took place after that date and the Entente Cordiale (Cordial Agreement) among the colonizing countries allowed effective use of the navigable waterways. OVERVIEW OF NIGER RIVER BASIN COUNTRIES AND BASIN HISTORY 9 Postcolonial Era During the independence movement in the 1960s, the above-mentioned treaties were abrogated and, in the spirit of free commerce, the nine Basin countries established joint customs houses and instituted taxes on imported goods. Beginning in February 1960, a working session between Mali and Nigeria defined the conditions for shared development of the Niger River Basin, with support from the president of Niger. The meeting of the 16th session of the Commission for Technical Cooperation in Sub-Saharan Africa, at Mamou, Guinea, in 1960, recommended cooperation and exchange of technical information and data among Basin hydrologists, although this did not occur immediately. The First Conference on the Niger River Basin in which all nine Basin countries participated was held in May 1961, at Segou, Mali. This first step in fostering cooperation among the Basin water users underscored the importance of coordination and the dangers of under- taking national projects on a unilateral basis. As the newly independent countries became members of the United Nations (UN), they also agreed to comply with UN international conventions, such as the Barcelona Convention of 1921 concerning the use and regime of international navi- gable waterways. The Second Conference on the Niger River Basin, held at Niamey in October 1963, resulted in a new act, signed by the nine Basin countries, which renewed navigational freedom on the Niger and its tributaries. It also introduced the principles for cooperation necessary to evaluate and implement development projects that could affect the river system.5 This act set the stage for the establishment of an intergovernmental organiza- tion for cooperation. The Niger River Commission was established at a meeting held at Niamey on November 25, 1964. The agreement establishing the commission defined new rules concerning agricultural and industrial use of water, water resources development, navigation, and transportation. The agreement was amended in 1968 and again in 1973 (Godana 1985). In 1980, the heads of state of the Basin countries signed a new convention to create the Niger Basin Authority (NBA), replacing the Niger River Commission. The text of this convention amended the agreement of 1964 and amendments of 1968 and 1973. The convention stated that the NBA's long- term objective was to promote cooperation between and among the member states and to ensure integrated development in all areas as part of devel- opment of its resources, particularly in the areas of energy, water, agricul- ture, forestry, transportation and communication, and industry. At the same time, it recognized each country's individual right to exploit resources within its portion of the Basin. A protocol signed in Faranah, Guinea, in November 1980, created the Niger River Basin Development Fund, referred to as FONDAS. The purpose of FONDAS was to have a financial mecha- nism to support the goals of the NBA. Despite this transition from commission 10 THE NIGER RIVER BASIN: A VISION FOR SUSTAINABLE MANAGEMENT to authority, which was intended to bolster the organization's institutional effectiveness and operational self-sufficiency, the lack of financial commit- ment on the part of member countries led to a gradual loss of credibility. Consequently, several development partners withdrew support.6 This situation prevailed until the 17th ordinary session of the NBA in Abuja, Nigeria, in 1998, when the ministers of the member states met to discuss this institutional problem and identify a mechanism to address sys- tematically the progressive degradation of the environment and water resources of the Basin. In February 2002, the nine heads of state met in Abuja to renew their political commitment to manage the Basin's water resources in a sustainable manner and to maximize development opportunities through multilateral cooperation. The NBA's heads of state agreed to launch the Shared Vision for the Basin's sustainable development, supported by the SDAP. Following this political commitment, the member states com- missioned an institutional audit of the NBA to strengthen its institutional capacity at the NBA's Extraordinary Council of Ministers meeting in Yaoundé, Cameroon, in January 2004. Following the Yaoundé meeting, the nine heads of state signed the Paris Declaration in April 2004, confirming the member states' commitment to the Niger Basin Shared Vision process.7 This process is further discussed in chapter 4. 2 The Physical Geography of the Niger River Basin Physical Environment and Hydrography The diverse geographic and climatic characteristics of the Niger River Basin play an important role in water resources availability, which in turn affects a range of water resources­related activities. The Niger River water system is one of the most impressive examples of the influence of topography and climate on the flow conditions of a water system. Such a large basin area cannot be expected to have uniform climatic and rain patterns, and the Niger River traverses almost all the possible ecosystem zones in West and Central Africa. A combination of human population growth, unsustained resource use and development, and desertification threatens the Niger River's ability to supply crucially needed natural resources to the people of West Africa. The geology and soils of the Basin also influence groundwater avail- ability. Significant rainwater deficits and the variable duration of the rainy season result in hydrological deficits that are not necessarily reflected in a direct response of the base flow. This chapter reviews the Basin's physical geography, six hydrographic regions, geology, groundwater and soils, natural environment, and climatic characteristics. Physical Environment The Niger River Basin is located between the meridians of 11°30' west and 15° east, from Guinea to Chad; and between the parallels of 22° north and 5° north, from the Hoggar Mountains to the Gulf of Guinea. The Basin extends 3,000 kilometers from east to west and 2,000 kilometers from north to south. Originating in the Guinean highlands within the regions of Haute Guinée and Guinée Forestière in the Fouta Djallon Massif, the Niger River is the third-longest river in Africa (4,200 kilometers), after the Nile and the Congo. The Upper Niger River takes its source from the Fouta Djallon Massif in Guinea at an altitude of about 800 meters and flows northeast, travers- ing the Inland Delta in Mali. The Inland Delta is a vast, spreading flood- plain (averaging 40,000 square kilometers) that dissipates a significant proportion of the flow of the river through absorption and evaporation. 11 12 THE NIGER RIVER BASIN: A VISION FOR SUSTAINABLE MANAGEMENT When it reaches the fringes of the Sahara Desert, the Niger River turns back by forming a great bend and flowing south and east as the Middle Niger River section, then as the Lower Niger to the Niger Delta at the Gulf of Guinea. Before reaching the Niger Delta, the Niger River is joined by its major tributary, the Benue River, which originates in the highlands of Cameroon's Adamawa Plateau. The full extent of the Basin has been the subject of debate, because there is no input to the Niger River system from its left bank as it runs through Niger. From the headwaters to the Niger Delta, therefore, taking into account the hydrologically active area, the Basin has an average area of about 1.5 million square kilometers. Hydrographic Regions The six hydrographic regions of the Niger Basin are distinguished by their unique topographic and drainage characteristics. Maps 2­7 in appendix 1 illustrate the hydrographic regions' geographic settings and characteristics. The regions are as follows: · The Upper Niger River Basin and the Bani Watershed. The headwaters of the Niger have an extensive network of steep-sloped tributaries orig- inating in Haute Guinée, whereas the Bani tributary network originates in the low-altitude plateaus of southern Mali and Côte d'Ivoire. · The Niger River Inland Delta and Lakes District. This region is charac- terized by an immense, fertile, shallow-sloped alluvial floodplain with an extensive dendritic tributary network and shallow lakes. · The Middle Niger, Malian-Nigerien, and Beninese-Nigerien Right-Bank Segment. This is a low-altitude plateau region with a series of tributaries that contribute to most of the Niger River's inflow along this segment. · The Middle Niger Left-Bank Tributaries. This region is characterized by a wadi network in the upstream reach of this segment, with little con- tribution to the Niger River and an increased inflow from the tributary network in the lower reaches of the segment. · The Benue River. This is a major tributary to the Lower Niger River orig- inating in the high-altitude Adamawa Plateau in Cameroon. · The Lower Niger River and the Niger Delta. Both these regions are located in a region of high rainfall, with an increase in the number of tributaries in the Lower Niger River, which flows south, emptying through the Niger Delta, an area characterized by swamps, lagoons, and navigable channels. The Upper Basin of the Niger River and the Bani Watershed. The Upper Niger River Basin extends between latitudes 8°35' and 14° north and longitudes 4° and 11°30' west, with its downstream limit at Ké Macina and San (see details in appendix 1, map 2). Over the first 40 kilometers from its headwaters, the river drops 300 meters (an average slope of 7.5 meters THE PHYSICAL GEOGRAPHY OF THE NIGER RIVER BASIN 13 per kilometer) toward the northeast. After passing the city of Faranah, it collects, in succession, the Balé and Tonboli tributaries, whose sources are located in the Fouta Djallon Massif. These tributaries are characterized by steep slopes, which explains the high flood levels of the Upper Niger. Upstream of Kouroussa, the Mafou is the first major tributary on the right bank of the Niger. It clears a series of rapids with a 10-meter drop along its downstream course. After passing the city of Kouroussa, it meets the Niandan, one of its main tributaries. Farther downstream, the Milo and the Tinkisso join the Niger from the right bank and the left bank, respec- tively, upstream of Siguiri. These are the largest Guinean tributaries of the Niger (although the Fie contributes more flow from Guinea, its confluence with the Niger is in Mali). Finally, the Sankarani joins the Niger from the right bank 40 kilometers upstream of Bamako, the Dion being its main tributary in Guinea. At the border with Mali, the Niger River has already traversed 600 kilo- meters. With its tributaries and subtributaries, it drains more than 100,000 square kilometers of Haute Guinée, an area characterized by rough terrain at the headwaters (these highlands are particularly prone to erosion because human activity has largely reduced the vegetation cover). From Siguiri through Bamako to Koulikoro the flatness of the terrain, caused by long- term erosion, is broken in places by lateritic buttes in the southwest; plateaus cap a vast range of sandstone hills of the Mandingue region in the northwest, sloping toward the northwest with walls reaching heights of 300 and 400 meters above the alluvial plain. Most of these areas are poorly suited for agriculture; only the alluvial plain of the Niger valley allows agricul- tural development. Between Bamako and Koulikoro, the Niger passes through two rapids (Sotuba and Kenie) before it flows gently into a vast plain that carries it to Segou and to the Markala Dam. Downstream of Segou-Markala, at Ké Macina, the river flows into the Inland Delta, with a riverbed slope of less than 2 centimeters per kilometer. At Ké Macina, the river has traversed about 1,000 kilometers from its source and has drained a watershed of 141,000 square kilometers. The Bani, a primary tributary of the Niger, is created by the confluence of the Bagoé and the Baoulé, whose headwaters are located within Côte d'Ivoire. This area is characterized by very flat plateaus at relatively low altitude (between 280 and 500 meters, with 70 percent between 300 and 400 meters). The only hills of any significance in the area are west of the Bandiagara Plateau (reaching an altitude of 791 meters around Koutiala). The Bani's course is almost entirely located in southern Mali. Soon after the confluence, the Bani valley widens and the streambed almost disap- pears. The floodplain becomes about 10 kilometers wide downstream of Douna after the confluence with the Lotio-Banifing, which drains the Sikasso area. The Bani enters the Inland Delta just after San. The slope becomes 14 THE NIGER RIVER BASIN: A VISION FOR SUSTAINABLE MANAGEMENT extremely gentle, at less than 2 centimeters per kilometer. However, on the right bank the floodplain is limited by a series of sandstone hills from which several small streams flow. The Bani's course in the floodplain progresses toward the north where several secondary branches emerge, feeding the Djenné region. It finally empties into the Niger at Mopti, 1,300 kilometers from its headwaters. The Bani River Basin's area above Mopti is 130,000 square kilometers. With nearly identical basin areas and dense hydrographic networks, the Bani and the Niger are distinguished by their respective slopes: The Niger has 24.4 percent of its entire surface area above 500 meters at Koulikoro, but the Bani has only 1.7 percent above this altitude and is characterized by much flatter topography. The Niger River Inland Delta and Lakes District. The Inland Delta originates at Segou and ends in Koryoume, Timbuktu's river port. This area forms a huge parallelogram, located along a southwest-northeast axis, 400 kilome- ters long and 125 kilometers wide, averaging about 40,000 square kilome- ters. This area is without well-established watershed limits (see details in appendix 1, map 3). The Inland Delta can range from 30,000 square kilometers during periods of low water to 80,000 square kilometers during periods of high water. From Segou, for the Niger, and from Douna, for the Bani, the river network enters into an immense alluvial plain filled with various Quaternary and recent deposits. This area, known by different names (central delta, lake basin, inland basin, or Inland Delta of the Niger), is characterized by the alluvial deposits and multiple branches that are commonly found in deltas at the mouth of rivers. According to Gallais (1967), the Inland Delta is defined by the maximum extension of floodwaters and peripheral lakes: · To the east and south by the slopes of the Bandiagara Plateau · To the west by the dead delta, an area of ancient deposits above the current delta · To the north by a series of dunes oriented east to west The Inland Delta comprises four distinct morphologic regions--the upper delta, the central delta, the lakes district, and the lower delta. Other authors have described these regions in detail (Gallais 1967, 1979; Blanck and Lutz 1990; McCarthy 1993; Poncet 1994). In brief, the Inland Delta includes: · The upper and central deltas, downstream from Ké Macina and Douna, combining two major branches. These branches of the Niger and Bani are sometimes referred to as the Malian Mesopotamia around Djenné in the upper delta, and Niger and Diaka for the plains of Kotia in the cen- tral delta. They extend to the lakes district (Lake Debo, Lake Wallado, THE PHYSICAL GEOGRAPHY OF THE NIGER RIVER BASIN 15 and Lake Korientze) and compose an immense discharge area largely inundated by the annual river flood. · The lower delta that extends from the outlet of the lakes district with three main drainage points (Issa Ber, Barra Issa, and Koli Koli) all the way to Diré. Here a different geomorphology, characterized by super- imposition over prior alluvial layers of a Holocene erg (sand sea) at Niafunke, with dunes oriented east to west, reveals a very diffuse water network. This network is dominated by interdune furrows that are often flooded and peripheral lakes fed by heavy floods. The Inland Delta stores a volume of water varying from 70 cubic kilo- meters in wet years to 7 cubic kilometers in dry years. The flood arrives at Koulikoro in September and spreads slowly through the floodplain, and does not pass Diré until three months later. Water storage in the Inland Delta is accompanied by water loss (seepage and evaporation) of about 44 percent of inflows. The area of the peripheral lakes in the Inland Delta is particularly sensitive to the hydrological operation of the Niger River. These lakes were the subject of hydrologic studies during the 1950s, which was a period of very high water (Auvray 1960). However, the droughts during the 1970s and 1980s greatly reduced water availability, limiting refilling of the lakes, especially those on the right bank and Lake Faguibine (Guiguen 1985). The surface area of the lakes as reviewed in table 2.1 reflects the max- imum extent, reached in the 1950s, a level that has not been reached again. By way of comparison, the surface areas of Lakes Debo, Wallado, and Korientze are 190, 70, and 57 square kilometers, respectively. The surface area of Lake Chad ranges between 5,000 and 25,000 square kilometers, 42 times the maximum surface area of Lake Faguibine and 11 times the total surface area of all the peripheral lakes of the Inland Delta of the Niger (Marieu, Kuper, and Mahieux 2000). The Middle Niger, Malian-Nigerien, and Beninese-Nigerien Right-Bank Segment. As the Niger River exits the Inland Delta, it enters the Middle Niger River segment, which extends to Lokoja (refer to appendix 1, map 4). As it flows through the Niger Bend and after clearing the weir at Tossaye, the Niger River passes through the wadi network of the Vallée du Tilemsi and takes a southeast direction. On the Tossaye-Ansongo reach (212 kilometers), Quaternary alluvial deposits fill a valley that is 4 kilome- ters wide. On the left bank, windblown deposits obstruct the exits of wadis originating in the Adrar des Iforas, the Oued Essalaoua upstream of Bourem, and the Tilemsi upstream of Gao. On the Ansongo-Niamey reach (352 kilometers), there is a succession of rapids at Fafa, Labezanga, and Ayorou, at 59, 109, and 144 kilometers from Ansongo, respectively, making this stretch one of the most difficult for nav- igation. The floodplain is about 2 kilometers wide. Labezanga marks the 16 THE NIGER RIVER BASIN: A VISION FOR SUSTAINABLE MANAGEMENT Table 2.1 Geographic Location, Maximum Surface Area, and Capacity of the Peripheral Lakes of the Inland Delta Maximum Maximum Lakes Geographic location surface area (km2) capacity (M m3) Tanda 15°45' N, 4°40' W 145 -- Kabara 15°45' N, 4°32' W 50 -- Tagadji 15°55' N, 4°08' W 90 -- Oro 16°12' N, 3°50' W 145 -- Fati 16°12' N, 3°42' W 140 -- Télé 16°27' N, 3°45' W 105 1,500 Faguibinea 16°47' N, 3°50' W 595 -- Gouber, Kamango 16°50' N, 3°40' W 120 -- Niangaye 15°50' N, 3°10' W 335 1,300 Do 15°55' N, 2°45' W 125 800 Garoub 16°03' N, 2°45' W 160 775 Haribongo 16°10' N, 2°45' W 55 290 Aougoundou 15°45' N, 3°18' W 85c -- Korarou 15°20' N, 3°15' W 135 150 Source: Auvray 1960. Note: -- not available. a. The western limit of Lake Faguibine is set between the villages of M'Bouna and Tin Aicha. Since the droughts of the 1970s and 1980s, the water has never reached this limit. The villages of Raz el Ma and Adarmalane are therefore not included in this table. b. The Garou Lake System includes Lakes Garou, Gakore, Tinguere, and Titolaouine. c. During his visit on November 11, 1999, Marieu, Kuper, and Mahieux (2000) estimated the surface area of the lake to be 38 square kilometers. This value is not definitive because the lake was not completely full. border between Mali and Niger. Downstream from Ayorou, the valley expands and collects, from its right bank, the first tributaries since the Bani. These include the Gorouol, draining the extreme north of Burkina Faso and the southern Mali region of Hombori, and two other tributaries originat- ing in Burkina Faso--the Dargol and the Sirba. On the Niamey-Malanville reach (336 kilometers), the first 100-kilometer section, to Kirtachi, crosses recent alluvial deposits. From Kirtachi to Boumba, the river traverses the Atakora sandstone massif for 100 kilometers through a narrow valley with abrupt changes in direction that form a "W" shape, from which the W International Park gets its name. From Boumba, the Niger flows through a wider valley (more than 4 kilometers wide) of allu- vial deposits to the border with Nigeria. Before the W Park, the Niger col- lects three tributaries originating in Burkina Faso: the Goroubi, the Diamongou, and the Tapoa. After the W Park, the Niger, which now borders THE PHYSICAL GEOGRAPHY OF THE NIGER RIVER BASIN 17 Benin, collects the three main tributaries of its middle watercourse, drain- ing the northeast of Benin: the Mekrou, the Alibori, and the Sota. On the left bank, endoreism is the most prevalent: Dallol Bosso (Azaouâk), Dallol Foga, and Dallol Maouri are wadis, with no water reaching the Niger River. The Middle Niger Left-Bank Tributaries. The Niger River continues in a southeast direction for 200 kilometers (see appendix 1, map 5) from the Niger-Nigeria border downstream to Yelwa. As it enters Nigeria, the Niger River collects some minor tributaries on the right bank (the Chodou, Wessa, and Kalia), all of which originate in Benin. A significant tributary on the left bank, the Sokoto, drains a large basin in the Sahelian region of Maradi, which encompasses the state of Sokoto-Rima and the northern portion of Kaduna state. Originating in the Gusau region, it collects the Rima--whose Nigerian section (Goulbins) in the upper basin starts in the dry valleys of the Aïr Massif--from the right bank, a short distance downstream of the city of Sokoto. From the left bank, the Sokoto-Rima River collects the Zamfara and the Ka. After its confluence with the Sokoto-Rima River, the Niger River flows into a large plain, traveling north to south for 200 kilometers toward Jebba. Its course flows through the Kainji Reservoir for 130 kilometers. Between Kainji and Jebba, the Niger collects more minor tributaries on the right bank, the Oli and the Moschi, and various small watercourses on the left bank, whose contributions taken together are significant. In Jebba, a second dam cuts the flow of the Niger River. At this point, the Niger River has recov- ered the flow volume that it had when it left Guinea, over 2,700 kilometers upstream. From Jebba to Lokoja, along a reach of nearly 400 kilometers, the Niger changes direction to the southeast and receives minor tributaries on the right bank--the Awun, Oshin, and Oro. About 150 kilometers downstream of Jebba, the Niger collects another major tributary from the left bank, the Kaduna, that drains an area of 65,500 square kilometers in the western part of the Jos Plateau. After taking a northwest direction, the Kaduna turns southwest, passing through the state capital of the same name, and collects several tributaries from the north, including the Mariga. With its steep slopes, the Kaduna is characterized by fast flows, strong floods, and severe lows that are indicative of a dry, tropical climate. At the end of this reach is Lokoja, where the Niger meets the Benue. The Benue River. The Benue headwaters are at an altitude of approximately 1,300 meters on the north slope of the Adamawa Plateau in Cameroon (see appendix 1, map 6). The Benue collects the Mayo Rey and Godi streams from the right bank before crossing a vast plain of alluvial deposits, passing through the Lagdo Gorge, now the site of a large reservoir, then reaching a wide alluvial plain through which it flows into Nigeria. 18 THE NIGER RIVER BASIN: A VISION FOR SUSTAINABLE MANAGEMENT Upstream of Garoua and 300 kilometers from its source, the Benue encounters the Mayo Kebi River that drains the marshy areas of the Kabia and the depression of the Toubouris Lakes in Chad, and channels strong torrents coming from the Mandara Mountains in Cameroon. The Mayo Kebi River is 420 kilometers long. At the confluence, the Benue takes a southwest direction, passes Garoua at an altitude of 175 meters and after flowing westward for a distance of 80 kilometers, it reaches the Nigerian- Cameroon border. There it collects the Faro, the powerful river from the Adamawa that is subject to strong floods and a large silt load. In Nigeria, the Benue passes Yola (60 kilometers inside the border); is supplied on the left bank by the Ini, a river coming from the Alantika and Shebshi Mountains; then collects (70 kilometers downstream from Yola) the Gongola, another strong tropical river coming from the northeast Jos Plateau, with a basin of 21,500 square kilometers. Like the Faro, the Gongola carries a heavy sediment load, making navigation difficult immediately downstream. The Benue then takes a southwest direction, which it will follow for approximately 450 kilometers, to Makurdi. On this reach, the right bank tributaries coming from the Jos Plateau remain small, whereas significant rivers enter the Benue from the left bank. They come from the mountain chains and massifs between Nigeria and Cameroon (Shebshi, Gotel Mountains, and the Bamenda Massif; the highest point in the Niger River Basin is 3,008 meters at Pic Oku, north of Bamenda in Cameroon). These rivers become larger as they flow south; the areas receive heavy rains. After the Belwa and the Fan, the Benue collects, in succession, the Taraba, the Donga, and the Katsina Ala, whose watersheds are 21,500, 20,000, and 22,000 square kilometers, respectively. The upper Donga makes up the border between the northwest province of Cameroon and Nigeria, and the Katsina Ala and its tributary, the Metchum, contribute considerable flows. Between Garoua and Makurdi, the Benue's volume of flow increases eightfold. Over the 220 kilometers that separate Makurdi from the confluence with the Niger at Lokoja, the Benue collects short tributaries on the left bank and stronger tributaries such as the Mada and the Okwa, coming from the southern Jos Plateau, on the right bank. At Lokoja, the Benue meets the Niger; at this point, the two waterways are about the same size, although the Benue has traveled 1,200 kilometers and the Niger has traveled almost 3,800 kilometers from its source. The Lower Niger River and the Niger Delta. At Lokoja, the Niger River enters the Lower Niger River segment, which includes the Niger Delta. From Lokoja, the Niger River takes a north to south direction for 200 kilometers; it receives only a few small tributaries, including the Anambra on the left bank, which drains a basin with significant rainfall. Onitsha is the last THE PHYSICAL GEOGRAPHY OF THE NIGER RIVER BASIN 19 monitoring station on the river. The Lower Niger flows for another 100 kilometers and the lower valley progressively transforms into the vast Niger Delta covering approximately 30,000 square kilometers, with no fewer than 30 outlets to the ocean. The main course of the Niger takes the name of Nun as it crosses the Niger Delta and discharges to the Gulf of Guinea, 4,200 kilometers from its source in Guinea. Navigable River Segments The Niger's navigable waters are a strategic axis for commerce. Although commercial travel routes have changed over time, efforts to link the land- locked segments with canals and land routes have provided access to the river's resources to all. The main navigable segments of the river, from the Niger Delta upstream to the Upper Niger, are described below and illus- trated in appendix 1, map 10. · In Nigeria, the overall navigable network in the coastal lagoons and river branches of the Niger Delta is more than 6,000 kilometers; half of that network is part of the Niger and Benue network (Sanyu and others 1995). Along the length of the Niger, navigation is possible for large flat- bottomed boats upstream to Onitsha (1,127 kilometers from the ocean) throughout the entire year, and even farther upstream to Jebba (1,448 kilo- meters) from August to February. Lake Kainji is navigable for 130 kilo- meters. The Benue is navigable to Makurdi from June to December, and to Garoua in Cameroon from August to November. · From Lake Kainji to the Niger border, the river is only navigable at very high water for 336 kilometers from the border of Nigeria (Malanville- Dolé) to Niamey from August to February. Upstream of Niamey, navi- gation is possible for another 170 kilometers from Tillabery to Meana. Rapids and rocks limit navigation over a 123-kilometer segment from Meana to Fafa, except in unusually high water. From Fafa to Ansongo, Gao and Tossaye (in Mali), medium-tonnage barges can follow a distance of 270 kilometers at high water, and navigation is generally permanent on the upper reaches for 327 kilometers between Tossaye and Timbuktu's river port of Koryoume. · From Koryoume to Ké Macina, most of the main stem is navigable from September to December, although the Inland Delta is open to small fish- ing boats all year. In addition, several tributaries are navigable in high water, although when the water is low the channel in Lake Debo is not navigable. Within the Inland Delta, Mopti is the main port, on the Bani tributary. Large barge vessels can navigate over 200 kilometers upstream through the locks of the Markala Dam near Kirango from August to 20 THE NIGER RIVER BASIN: A VISION FOR SUSTAINABLE MANAGEMENT January. From Koulikoro to Bamako, there is a continuously navigable waterway in high water (August to January). · Upstream of Bamako, small fishing vessels can navigate seasonally (August to November) to Siguiri, and similarly, through Guinea, in the low valleys of the Niger River and the Milo and Tinkisso tributaries. There is no real commercial traffic established between Mali and Guinea. There is great potential to develop the Niger Basin's transportation net- work to expand access to markets and commerce, and to increase labor flows. This potential is not fully exploited and existing navigational segments are underutilized. There is a need to improve the transportation network to foster regional integration among and between the countries. Geology and Hydrogeology Groundwater base flow heavily influences the Niger River, with dry season contributions primarily within the alluvial plains. In general, groundwater tables are affected by annual rainfall and soil permeability. Groundwater is extremely important for potable water supply (which is of excellent qual- ity in most cases) for both urban and rural settlements. Several international and bilateral donors and nongovernmental organizations have financed research and development work on small aquifers and village water sys- tems, although more needs to be done to understand the hydrodynamics of the aquifers in the Basin. The Basin's geology ranges from ancient Archean formations to recent alluvial deposits, each with its own hydrogeologic potential in the Basin's different hydrographic regions. Upper Basin An ancient geologic landscape of crystalline rocks characterizes the upstream area of the Basin and most of the river's right bank. Groundwater occur- rence is very limited in these rocks, which are generally impermeable except where they have been fractured or are weathered, which creates small aquifer zones. Groundwater replenishment from the headwaters is therefore gen- erally very low (Fontes and others 1991). Examples of these formations follow: · An Archean base of granite, gneiss, and mica schist is found in the Guinean section of the Basin, northern Côte d'Ivoire, southwest Mali, most of Burkina Faso, and northern Benin, with a few basic intrusions (dolerite and gabbros) in Guinea at the Fomi site, and in Niger near Tillabery. THE PHYSICAL GEOGRAPHY OF THE NIGER RIVER BASIN 21 · Middle and Early Precambrian schist and quartzite appear in the lower valleys of the Niger tributaries in Guinea and Mali, in the tributaries of the Bani in Côte d'Ivoire and Burkina Faso, and southeast of the Niger Bend in Bourem, Gao, Ansongo, and in the Niamey Valley. · Cambrian schist and sandstone extend from Bamako to Sikasso. · Ordovician sandstone-quartzite and various sandstones are found in the Dogon region, on the Mandingue Plateau, and on all the plateaus between Koulikoro, Koutiala, and Bandiagara. Inland Delta Downstream of Koulikoro in the Inland Delta, north of Segou, and also in the Gondo depression east of the Dogon region, Quaternary and recent deposits mask the substratum and, in particular, the Eocene to Pliocene Continental Terminal. These recent deposits are either alluvial or dunelike Holocene ergs, with groundwater aquifers linked to the waterways. The Continental Terminal is a continuous stratum aquifer composed of clay- like sandstone, sand, and clays, with good water quality. It appears on the left bank of the Niger at Goundam, Timbuktu, and Gourma Rharous, then continues through Bourem and Gao to Niamey and Gaya, with an exten- sion north inclusive of the sedimentary basins of Taoudenni, the Azaouâd, the Tilemsi, and the Azaouâk. The Continental Terminal aquifer is the most significant aquifer in the Basin and is widely used, particularly in Niger. The stratum is immense: It is not unusual to see aquifer thicknesses of over 100 meters extending over tens of thousands of square kilometers. Underneath the Continental Terminal and the Eocene and Cretaceous layers of these sedimentary basins lies the Continental Shale Band aquifer, which borders the Niger River just north of Benin but is also present in the semiarid area of Mali and Niger. This aquifer has abundant groundwater, but is generally of poorer quality than that of the Continental Terminal. Lower Niger On entering Nigeria, the Niger flows through a series of sedimentary deposits: Tertiary deposits on the left bank--a continuation of the Continental Terminal observed in Niger, frequently with artesian aquifers--followed by Cretaceous deposits that continue to Onitsha on the Lower Niger. From Jebba, Quaternary alluvial deposits fill the large plains located on both sides of the river, extending in the Benue valley all the way to Chad. This sedi- mentary basin, with remnant marine properties from the Cretaceous era, rises toward the east throughout the Benue valley in Cameroon and Chad, the farthest reaches of the Cretaceous Sea. Schist, limestone, and sandstone make up the Cretaceous layer in these areas; deposits are thick and the 22 THE NIGER RIVER BASIN: A VISION FOR SUSTAINABLE MANAGEMENT aquifers are often of very good quality. From the Onitsha area, the Tertiary marine layer crosses through the Cretaceous layer, and is then covered by Quaternary sediments from the coastal plain and delta. Outside this sedimentary basin, the African Precambrian base predom- inates in the Niger River Basin, in southwest Nigeria, and in the central area of the Jos Plateau, Abuja, Minna, Kaduna, and the upper Sokoto, and extend- ing to the Adamawa and other mountainous boundary massifs in Cameroon. It is composed of gneiss, ancient granite, and quartzite, with limited ground- water potential except in weathered zones that can produce useful local supplies. Soils The three major soil types of the Niger River Basin, according to the French soil nomenclature (World Bank 1986), are ferralitic soils, tropical ferrugi- nous soils, and hydromorphic soils (figure 2.1). The characteristics of these three types of soils determine the nature of agricultural productivity in the Basin. As a result, agricultural development varies in the Basin with the geographic distribution of the specific soil. The characteristics for each soil type are described below: · Ferralitic soils are seen in the extreme west of the Guinean basin of the Niger, in the south of the Bani watershed, in the north of Benin, and in the major part of the Niger River Basin in Nigeria, including the Benue water- shed. These are thick soils (from 3 to more than 10 meters thick), where geochemical changes are extensive and spread over many millions of years. · Hardened lateritic layers can be seen on the surface or at short depths on top of a mix of the ferralitic and ferruginous soils; they are found in particular in Guinea and in southern Mali. This concreted and hardened horizontal layer results from an upward migration of ferrous oxides and from their precipitation. Limited spots of tropical brown soil or tropical black clay (vertisols) can also be found. · Bleached layers of ferruginous tropical soils are seen in the north of the Bani watershed, on the periphery of the Inland Delta in Mali, in the east of Burkina Faso, and along the northern part of the Niger River Basin and Benue watershed in Nigeria and Cameroon. They are associated with ferralitic soils in the Upper Niger River Basin upstream of Bamako and in the Kaduna watershed in Nigeria. Alternating dry and wet seasons, characteristic of the watershed's climate, have caused discontinuous changes in the rock over time. The changing layers have a variable thick- ness but are always less than 3 meters deep. THE PHYSICAL GEOGRAPHY OF THE NIGER RIVER BASIN 23 Figure 2.1 Schematic Map of West African Soils 10 0 10 20° 20 Timbuktu Agadez Dakar Niger Bani Mopti Bamako Niamey Niger Ouagadougou 10 10 Conakry 500 km Abidjan 10 0 10 Raw mineral desert soils Washed tropical ferruginous soils Poorly evolved subarid soils Hydromorphic soils Isohumic soils (subarid brown soils) Lightly or average saturated ferralitic soils Little washed or unwashed Association of tropical ferruginous washed ferruginous tropical soils soils and ferralitic soils Water courses Limit of watershed basins Source: World Bank 1986, modified by Picouet 1999. The tropical ferruginous soils characteristic of a short wet season, which are little or not at all bleached, cover a large band in the north, from Mopti to Niamey and Maradi. Even farther north, subarid isohumic brown soils are present from Gourma to Gao (Mali), and in Niger. Sandy dunes, poorly evolved subarid soils, and lithosols characterize this section and indicate that the Niger River has reached the Sahara. Hydromorphic soils, linked to the presence of a temporary or perma- nent aquifer that is close to the surface, can be found in lake basins, riverbeds, and low clay plains. Almost all of the soils in the Niger's Inland Delta are of this type; 74 percent are flooded every season in the active Inland Delta (PIRT 1983). 24 THE NIGER RIVER BASIN: A VISION FOR SUSTAINABLE MANAGEMENT Natural Environment The Niger River ecosystem corridor has provided people with sustained livelihoods even in the harshest drought conditions. The environment in its natural state and under pressure affects and is affected by the Niger. The Natural Environment Along its course, the Niger River traverses almost all the possible ecosystem zones in West Africa. The Niger River's headwaters are located at an altitude of 800 meters, at the fringes of the Guinean moist forests. The river then passes through woody savannas and areas of sedge vegetation. At the west- ern edge of the Inland Delta is a short-grass savanna, with thorny shrubs and acacia wood, followed by a region of tussocky grass interspersed with dense wooded vegetation. The eastern Inland Delta is made up of Sudano-Sahelian flooded grasslands and a labyrinth of 50,000 to 80,000 square kilometers of wetlands and lakes. The floodplains are pastures of bourgou grass that support livestock, wildlife, and fish nurseries. In the wetlands, flora have adapted to extreme fluctuations in water levels. At the Niger Bend, the river reaches the fringes of the desert. The high rainforest belt begins farther south, at Onitsha. This belt merges below Aboh, in Nigeria, with mangrove forests and swamp vegetation in the Niger Delta. The Niger River system sustains an extensive biological community, hosting diverse ecosystems that harbor 36 families and nearly 243 species of freshwater fish, of which 20 are found nowhere else (11 of the 18 families of freshwater fish that are endemic to Africa are represented in the Niger River). Species in the river range from West African manatees and hippopotamuses to crocodiles. There is a rich collection of transmigratory birds found in the Inland Delta, among them black crowned cranes, herons, egrets, and storks; pelicans and flamin- gos are found in the upper Benue. The Niger Delta also includes an extensive mangrove forest. The Natural Environment under Pressure A combination of human population growth, unsustainable resource use and development, and desertification is threatening the Niger River's ecosys- tems and ability to supply crucially needed natural resources to the people of West Africa. River flow in the Basin is decreasing and fishing pressure is increasing, leading to drastic declines in production of fisheries. Deforestation and farming of fragile soils contribute through erosion to sedimentation in river channels. Waterborne diseases have increased and invasive aquatic species have spread, choking river channels. THE PHYSICAL GEOGRAPHY OF THE NIGER RIVER BASIN 25 Climatic Conditions The Basin has two distinct seasons--a rainy summer and a dry winter-- except for Nigeria, which has four seasons.8 Situated between the equator and the Tropic of Cancer, the region is generally warm or hot, although the high mountains and Sahara Desert experience extreme temperatures. Along the coast, the annual average temperature range is 21°­28°C (70°­82°F); inland to the north the temperatures fluctuate more according to the season, with an annual average temperature range of 12°­29°C (54°­84°F). Given its geographic setting in West and Central Africa, the Niger Basin is charac- terized by the climatic conditions associated with the movement of air masses of the Intertropical Convergence Zone north and south of the equa- tor. During the boreal summer (June to November), the rise of the Saint Helena high-pressure area toward the north signals the beginning of the monsoon season, with humid and unstable maritime equatorial air and relatively cool temperatures. The monsoons are longer and heavier in the southern part of the Basin. The boreal winter (December to May) is the dry season; under the influence of a Saharan high-pressure zone, the north- eastward harmattan wind brings hot, dry air and high temperatures, which last longer in the north. Annual rainfall ranges from fewer than 100 millimeters (4 inches) in the Sahel zone to more than 1,200 millimeters (48 inches) along the pure tropical areas in the Guinea zone. The regional climate classification as defined by annual rainfall, according to Maley (1982), and reviewed and modified by L'Hôte and Mahé (1996), is noted in table 2.2. The upper half of the Niger River Basin encompasses five climate zones (see figure 2.2), which are based on the duration and abundance of annual Table 2.2 Climate Classification for West Africa from South to North Annual rainfall Climate classification (mm) for Western Africa Climate classification French classificationa 1,200 Sudanese II and III Transitional tropical Tropical de transition 750­1,200 Sudanese I Pure tropical Tropical pur 300­750 Semiarid south Semiarid tropical Tropical semi-aride 150­300 Semiarid north Semiarid desert Semi-aride désertique 100­150 Saharan Desert (arid) Désertique Sources: Maley 1982; L'Hôte and Mahé 1996. a. See figure 2.2. 26 THE NIGER RIVER BASIN: A VISION FOR SUSTAINABLE MANAGEMENT Figure 2.2 Geographical Distribution of Different Types of Climate in Africa Desert (arid) 20 Desert (arid) Faya-Largeau 100mn Semiarid desert Timbuktu 15 Semiarid Semiarid tropical Semiarid desert 400mn Pure tropical Niamey desert Ouagadougou Semiarid tropical 700mn 10 Nattingou Odienne Transitional tropical Pure tropical Transitional equatorial 5 Yaoundé Bitam Pure equatorial 0 Transitional equatorial 5 15 10 5 0 5 10 15 20 25 Source: L'Hôte and Mahé 1996. rainfall. The rainy season is centered in the month of August for all these climate zones. The five zones as they extend across the region can be described as follows: · The Guinean region, which includes the headwaters of the Niger River Basin and its tributaries, is characterized by a transitional tropical climate (tropical de transition) that is often called the Guinean Climate, where the annual rainfall is greater than 1,200 millimeters. · The region encompassing Siguiri-Sikasso is characterized by a pure tropical (tropical pur) climate, with annual rainfall between 750 and 1,200 millimeters. · The areas around Mopti are characterized by a semiarid (semi-aride) trop- ical climate, with annual rainfall between 300 and 750 millimeters. · The areas of the Inland Delta around Timbuktu have a semiarid desert climate (semi-aride désertique), with annual rainfall between 150 and 300 millimeters distributed over three to four months. · Apart of the Inland Delta is characterized by a desert climate (désertique), with less than 150 millimeters of annual rainfall distributed over the three summer months. THE PHYSICAL GEOGRAPHY OF THE NIGER RIVER BASIN 27 After the Niger Bend, the river crosses all of these climate zones in reverse, with the same type of annual rainfall distribution: · The desert region, including the landlocked wadi valleys in Mali and Niger, is limited in the south by the Malian-Nigerien border. · The semiarid desert, which includes Burkina Faso, continues all the way to Benin and northern Sokoto in Nigeria. · The semiarid tropical region covers northern Benin and the latitudinal band extending from Gaya (Niger)­Kainji (Nigeria) to Maroua-Garoua (Cameroon). · The pure tropical region covers most of the Basin in Nigeria, the Jos Plateau, and the Adamawa. · The transitional tropical region covers lower Nigeria. Appendix 1, map 11, illustrates the average annual rainfall patterns in the Basin and appendix 1, map 12, illustrates representative annual rainfall distribution throughout the Basin for both dry and wet months. Additional regional and site-specific information on climatic characteristics, annual and monthly rainfall, temperature, humidity, and evaporation rates in the Niger River Basin can be found in appendix 2. Climate and Water Resources Variability The variable duration of the rainy season and significant rainfall deficits in this large basin result in hydrological deficits that are not necessarily reflected in a direct response of the base flow. Variability in Rainfall Studies on climate variability in West Africa show a significant decrease in both the amount of annual rainfall and the duration of the rainy season. Carbonnel and Hubert (1992) detect a 19-year climate variation for the period 1970­89. L'Hôte and Mahé (1996) compare the rainfall average during the period 1951­69 with the period 1970­89 and determine a southward move- ment of isohyets in the range of 150­250 kilometers, depending on the Basin climate zone. Figure 2.3 highlights this southward movement of rainfall vari- ability. Furthermore, analysis of monthly rainfall data for the whole region by Le Barbe and Lebel (1997) shows that the dry period is characterized by a decrease in the number of rainy events, but the mean storm rainfall varies little.Adeficit of 10 percent to 30 percent in rainfall generally leads to a deficit of 20 percent to 60 percent in river discharges, confirming that rainfall in the Basin varies considerably but river discharges vary still more. 28 THE NIGER RIVER BASIN: A VISION FOR SUSTAINABLE MANAGEMENT Figure 2.3 Highlights of Isohyets Moving Southward 18 14 10 6 2 2 6 10 14 16 250 500 1000 12 1500 8 1500 4 Mean 1851­1969 Mean 1970­1988 0 120 240 360 480 600km Source: L'Hôte and Mahé 1996. Relationship between Rainfall and Runoff Olivry (1998) notes that the long-term relationship between rainfall and river flow is largely influenced by groundwater base flow, as is the case of the Niger River. Cumulative dry periods contribute to a reduction in base flow, and a return to sustained river flow requires replenishment of the aquifers, which is possible only with cumulative rainy years. Regionally, this return is referred to as the "memory of the river." Several studies in the Niger and Bani upper basins confirm the correlation between decreased rainfall and low river flows, as illustrated in figure 2.4. Because ground- water base flow varies with, and responds to, the rainfall from previous years, the river flow in turn fluctuates with the level of aquifers, especially during a series of dry years. The dry years in the early 1970s, known in western Africa as la grande sécheresse (the great drought), saw the flow of the Niger River decline to unprecedented low levels. Yet a subsequent decrease in the rainfall deficit, or increase in rainfall, in the latter half of the 1980s does not correlate with the flow variation (figure 2.5). The Niger River's delayed hydrological responses illustrate that it takes more than a good rainy year to return the river to its previous flow. THE PHYSICAL GEOGRAPHY OF THE NIGER RIVER BASIN 29 Figure 2.4 Correlation between Annual Rainfall and Runoff on the Niger River at Koulikoro 700 Before 1970 y 0.56x 435.4 600 R2 0.79 500 After 1970 (mm) y 0.59x 516.54 400 runoff R2 0.71 300 Annual 200 Before 1970 After 1970 100 1,100 1,200 1,300 1,400 1,500 1,600 1,700 1,800 1,900 Annual rainfall (mm) Source: Olivry 1997. Note: y regression; R2 squared correlation. Figure 2.5 Yearly Variation of Average Rain and Flow Indices for Sudano-Sahelian Africa since the Beginning of the 20th Century 40 80 Rainfall index Flow index 30 60 % 20 40 variation average 10 20 from from 0 0 10 20 average variation 20 40 % 30 60 40 80 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 Source: Olivry and others 1993. 3 The Niger River Basin's Water Resources Hydrology From available information, chapter 3 evaluates the Niger River Basin's water resources in the six hydrologic reaches. This chapter examines the hydrology and water quality of the Niger River in some detail, using the same hydrographic regions described in chapter 2. Introduction The Niger's hydrology is as extraordinary as its hydrography, undergoing remarkable changes in its hydrologic characteristics as it travels from its headwaters to the Gulf of Guinea. From a simple tropical system with abun- dant rainfall at its headwaters in the Upper Basin, the Niger moves north- east into the Inland Delta, losing both flow volume and velocity as it meanders near the Sahara. Then, as it flows southeast after the Niger Bend, inputs from other tributaries make up these losses little by little. After its confluence with the Benue, the Niger River continues as a large river to the Niger Delta. Appendix 1, map 13 illustrates the flows at various points along the Niger River Basin, including the significant losses within the Inland Delta and around the Niger Bend. Unlike other major West African rivers, such as the Senegal and the Volta, the lower reaches of the Niger River are sustained during periods of low flow in the spring by the arrival of the waters from the previous summer's flood in the upper Basin. This phe- nomenon is known as the black flood in Niger. The annual flood in Nigeria, rich in sediment, is in phase with the summer rains and is known as the white flood. This process is illustrated in figure 3.1 and described by Pardé (1933; translation of this passage by the authors): The lower Niger, by its curve at two ends, leads one to believe in double supply, and this is a false impression. In reality, throughout its basin, this river has only one rainy period, that of a tropical summer. But the particu- larities of its topography and profile, in length and breadth, curiously doubles the high water season. The Senegalese Niger near Bamako and the lower stretch, downstream of Say, experience a prominent summer flood 30 THE NIGER RIVER BASIN'S WATER RESOURCES 31 Figure 3.1 Example of the Hydrograph of the Niger River at Its Entry to the Niger Delta 7 Lower Basin's tropical rains 6 5 (m) 4 water 3 of Height 2 1 Upper Basin's delayed flood 0 1 May June July Aug. Sept. Oct. Nov. Dec. Jan. Feb. March April Source: Pardé 1933. cresting in September. But the volume set in motion along the upper water course soon slows significantly, and partially dries up through evaporation and infiltration, before the river's "Big Bend" at Timbuktu, because of the gentle slope and the enormity of the flood plain where the water disperses and almost comes to a halt. The main flow, which passes Koulikoro generally about September 25, does not arrive in Timbuktu until about January 1; then it does not reach Niamey, when it is very low, until about February 2, six months after the rains that produced it. On the lower Niger, this Senegalese flood, slowed down in a manner not seen anywhere else in the world, does not participate in the local summer flooding; but it slows the drop in water, from November or December; it ends up by causing a gradual rise up to a maximum in March that is significantly lower than that of September. This is the most impressive example of the influence of topography on the flow conditions of a water system. For the purposes of description, the Niger River is divided into six hydro- logic regimes, to match the six hydrographic regions described in chapter 2. 32 THE NIGER RIVER BASIN: A VISION FOR SUSTAINABLE MANAGEMENT · The Upper Niger River Basin and the Bani Watershed · The Niger River Inland Delta and Lakes District · The Middle Niger, Malian-Nigerien, and Beninese-Nigerien Right-Bank Segment · The Middle Niger Left-Bank Tributaries · The Benue River · The Lower Niger River and the Niger Delta Appendix 1, map 14 shows the location of the Hydrological Forecasting System in the Niger River Basin (HYDRONIGER) data collection and mon- itoring stations along the river and major tributaries. Appendix 1 also includes maps with geographic details of these regions (maps 2­8), and appendix 2 provides detailed technical supporting data and information on flows, rainfall, evaporation, and sediment transport in the Basin. Appendix 3 provides an overview of the history of data collection and man- agement in the Basin. The Upper Niger Basin The Upper Basin of the Niger River and the Bani Watershed (see appen- dix 1, map 2) contains four primary tributaries of comparable size: the Niger, referred to as the Djoliba (watershed of 18,600 square kilometers); the Niandan (12,700 square kilometers); the Milo (13,500 square kilometers); and the Tinkisso (19,800 square kilometers). The first three watersheds receive abundant rain, sometimes more than 2,000 millimeters per year at the headwaters; they are also steep, with high levels of mean annual runoff: 563 millimeters on the Milo, 531 millimeters on the Niandan, and 442 mil- limeters on the Niger at Kouroussa. Mean annual runoff for the Tinkisso at Ouaranin in the north, by contrast, drops to 244 millimeters. These values were calculated over the period of 1950­2000 and include both wet and dry periods (Rodier 1964; Bamba and others 1996; Sangaré 2001). The Upper Basin above Siguiri has a surface area of 67,600 square kilo- meters and a mean annual flow of 948 cubic meters per second, equaling an annual runoff of 438 millimeters. Over the same 50-year period (1950­2000), the rain received by the watershed was 1,520 millimeters per year; the flow deficit is 1,082 millimeters, which can be attributed solely to actual evapotranspiration. The transitional Guinean Climate system explains the sustained flows observed from June to January, with several flood peaks and a maximum flow typically September­October; the low-flow season lasts only four months, with the lowest level April­May. Table 3.1 gives the mean monthly flows of the four main branches of the Niger in Guinea. The Banankoro station monitors the flow of the Niger River entering Mali, which differs only a little from the flow at Siguiri. Farther downstream, the Niger receives the Sankarani River. The Sankarani watershed, two-thirds Table 3.1 Mean Monthly Flows at the Four Main Branches of the Niger River in Guinea cubic meters per second Station Jan. Feb. March April May June July August Sept. Oct. Nov. Dec. Avg. year Niger to Kouroussa 52.6 25.4 13.5 8.76 12.3 57.4 180 414 682 595 299 112 232 33 Niandan to Baro 49.1 26.3 17.0 14.6 30.5 108 257 464 679 544 282 103 215 Milo to Kankan 35.2 20.0 14.4 16.0 29.2 81.6 229 439 599 412 179 70 177 Niger to Siguiri 200 103 58.6 44.0 67.1 231 804 2,054 3,304 2,708 1,244 454 948 Source: Brunet­Moret and others 1986. 34 THE NIGER RIVER BASIN: A VISION FOR SUSTAINABLE MANAGEMENT of which are in Guinea, covers 35,500 square kilometers at the confluence; the river is monitored at the Selingue gauging station. The first monitoring station on the Niger River was installed at Koulikoro in 1907, providing a valuable historical reference. The record of the Niger's flow at this station and the record of the flow at the Bakel monitoring station on the Senegal River together make up the longest and most complete dataset that exists, showing hydroclimatic variations in West Africa since the begin- ning of the 20th century. Above the Koulikoro gauging station, the watershed has a surface area of 120,000 square kilometers, one-fifth of which is in Mali. The mean annual flow calculated over 83 years is 1,420 cubic meters per second, providing a specific runoff flow (calculated as surface area) of 11.8 liters per second per square kilometer. The annual runoff of 370 mil- limeters is 25 percent of the mean annual rainfall, estimated at 1,500 mil- limeters, with losses caused by evapotranspiration of 1,130 millimeters (Brunet-Moret and others 1986). The largest floods were observed in 1924 and 1925 at 9,409 and 9,669 cubic meters per second, with the last major flood (at 9,344 cubic meters per second) in 1967. The mean annual low flow over 73 years, before the Selingue Dam, was 25 cubic meters per second. The Bani Basin The Niger River is joined by the Bani River, an important tributary, at the Inland Delta. The Bani is monitored at the Douna station (watershed of 101,600 square kilometers). Between 1953 and 1990, the mean annual flow was 419 cubic meters per second or a specific runoff flow of 4.12 liters per second per square kilometer, three times lower than that of the Upper Niger. The mean annual runoff was 130 millimeters, or 10.8 percent of mean rain- fall of 1,200 millimeters. Although having a similar area to the Upper Niger above Koulikoro, the Bani watershed receives less rain and has much lower runoff. The Bani flow therefore represents only 11 percent to 41 percent of the total flow at Koulikoro, depending on the year. Seasonal Variability The rainfall pattern over the Upper Niger and Bani watersheds creates a large seasonal variation in flows and monthly distribution of runoff in the watersheds, and causes significant variations between low-water and flood stages. Along the Niger, for six months (January through June) low flows represent less than 8 percent of the total annual flow. The increase in flow begins in May but does not become significant until July. The monthly runoff coefficients (that is, runoff as a percentage of rainfall) are 17 percent, 30 percent, and 25 percent in August, September, and October, respectively. The highest flood level generally occurs during the second half of September, a slight delay from the maximum rainfall in August. More than 80 percent THE NIGER RIVER BASIN'S WATER RESOURCES 35 of the annual flow is accounted for during August to November. The flood recession, rapid and rather regular, is characterized by two phases. The first phase corresponds to the depletion of surface water; the second phase, which is characterized by a rapid drop in base flow at the end of November, cor- responds to the seasonal depletion of shallow aquifers. This cumulative draining of small shallow aquifers, whose recharge depends solely on infiltration of rainwater runoff, is characteristic of the gen- eral geomorphology of intertropical Africa (Olivry, Bricquet, and Mahé 1998). A study covering nine representative watersheds in Mali shows that, for some, an important part of the flow originates from delayed base flow, with inflows from draining of marshes and from groundwater storage, notably in southern Mali and northern Côte d'Ivoire (Joignerez and Guiguen 1992). Flooding in the Upper Basin Both the Upper Niger River and the Bani River are subject to large annual floods (Rodier 1964). Heavy rainfall, which is spatially limited, does not necessarily correspond to high annual flows, due to the large size of the watersheds. The annual maximum flow does correlate well with the annual runoff (Olivry, Bricquet, and Mahé 1998). The frequency analysis for aver- age flows and highest flood flows in wet, average, and dry years is pre- sented in table 3.2. Floods in the Upper Basin have been as high as 1,500 cubic meters per second on the Tinkisso at Ouran, 1,000 cubic meters per second on the Milo at Kankan, and 1,500 cubic meters per second (and 1,960 cubic meters per Table 3.2 Frequency Analysis of Observed Hydrological Parameters in the Upper Niger River Basin cubic meters per second Average Wet years years Dry years Recurrence interval 100 20 10 2 10 20 100 Average flows Koulikoro 2,366 2,089 1,940 1,419 898 750 472 (Niger River) Douna (Bani River) 918 854 827 419 153 84 70 Highest flood Koulikoro 9,330 8,290 7,735 5,590 3,800 3,300 2,260 (Niger River) Douna (Bani River) 4,460 3,560 3,480 2,425 806 565 364 Source: Olivry and others 1995. 36 THE NIGER RIVER BASIN: A VISION FOR SUSTAINABLE MANAGEMENT second in 1962) on the Niandan at Baro. The high flood levels on these trib- utaries generally occur in the latter half of September and are almost in phase with the annual flood arriving at Siguiri, where the highest recorded flow level reached 5,930 cubic meters per second in 1962, with the 10 high- est recordings exceeding 5,000 cubic meters per second over the past 50 years. The lowest flow levels, which had been, on average, 50­60 cubic meters per second for the Niger at Siguiri, fell to fewer than 20 cubic meters per second in the last quarter of the 20th century. Despite the occasional high flows, the generally low-impact "flooding power" of the Upper Niger and Bani is typical of watercourses in arid Africa. These two watercourses drain different areas in terms of topography and rainfall; thus, their floods do not have the same power, nor do they occur at the same time. However, the upper basins of both the Niger and Bani can generally be characterized by gentle slopes, low permeability, floodplains that absorb overflows, and the episodic nature of the rainy season, referred to as the African monsoon (Rodier 1964). The Upper Niger system is heav- ily dominated by the rainfall in the Upper Guinean Basin, and lower rain- fall in the Bani watershed explains its lesser contribution. The Inland Delta and Lakes District The Inland Delta, with its system of lakes on both banks of the Niger River, is the result of the immense discharge from the Upper Niger Basin and Bani tributary. The Inland Delta covers approximately 40,000 square kilometers--of which 20,000­30,000 square kilometers are floodplains-- but can expand up to 80,000 square kilometers (see appendix 1, map 3). The hydrological characteristics of the Niger River's Inland Delta and lakes district are largely dependent on · Exogenous runoff conditions, with most of the water resources coming from upstream areas with higher rainfall; and · Morphological and climatological conditions specific to the Inland Delta, affecting runoff (water loss, flooding) and water balance (evaporation, infiltration). A comparison of the average annual flows in three typical years (high, average, and low) from Koulikoro to Tossaye is summarized in table 3.3. The year 1954 corresponds to a typical wet year, 1968 to an average year, and 1985 to a typical dry year. An assessment of these flows shows that runoff, monitored at the entry of Diaka and after the Bani confluence at Mopti, had already lost about 18 percent (during a wet year), 14 percent (during an average year), and 6 percent (during a dry year) of its initial contribution. The losses were even more significant when the flooded area THE NIGER RIVER BASIN'S WATER RESOURCES 37 Table 3.3 Example of Flow Progression from Koulikoro to Tossaye for Three Different Years cubic meters per second Wet year, high flow Average year, average flow Dry year, low flow Station (1954) (1968) (1985) Koulikoro 2,075 1,445 915 Ké Macina 1,951 1,306 765 Bani Douna 926 456 150 Bani Sofara 646 382 130 Diaka/Kara 642 409 255 Niger Mopti 1,702 1,098 604 Diré 1,522 1,118 619 Tossaye 1,457 1,033 574 Source: Olivry and others 1998. increased, with greater inflows from secondary tributaries. In relation to input from the Upper Niger at Ké Macina and the Bani at Douna, the flows at Diré, at the downstream end of the Inland Delta, show a loss within the delta of about 47 percent (a wet year), 37 percent (an average year), and 32 percent (a dry year). Evaporation in the Inland Delta The Inland Delta has an estimated storage capacity varying from 7 cubic kilometers to 70 cubic kilometers, with a high rate of loss caused by evap- oration over the thousands of square kilometers of its floodplains. This loss, estimated at about 44 percent of the inflow, constitutes an important source of evaporation in West Africa. The regression in figure 3.2 illustrates the correlation between flow input to the Inland Delta (at Ké Macina and Douna) and flow at the outlet (at Diré), thus reflecting the water losses in the Inland Delta (see appendix 1, map 13). An assessment of annual volume losses shows that they can reach 25 cubic kilometers between entry into the Inland Delta and the outlet at Diré for a wet period, and 7 cubic kilometers for a dry period, corresponding to a ratio of 14 to 4. The range of extremes has been from 40 cubic kilometers to 6 cubic kilometers in annual volume loss. For example, during a 25-year dry period (1970­95), the base flow of the tributaries dropped 46 percent against a drop in rainfall of only 19 percent. Outflows represented 54 percent of inputs in wet periods and 65 percent in dry periods. In other words, losses in the Inland Delta are lower in absolute value but also in relative value in dry years. 38 THE NIGER RIVER BASIN: A VISION FOR SUSTAINABLE MANAGEMENT Figure 3.2 Correlation between the Input at Ké Macina/Douna and the Losses at Diré in the Inland Delta from 1955 to 1997 /s) 1,400 3 data from 1991 to 1997 (m 1,200 Diré at 1,000 800 outlet 600 delta at 400 flow y 0.5294x 189.33 200 R 0.99 and N 23 Water 0 0 1,000 2,000 3,000 Water flow at delta inlet at Ké Macina Douna (m3/s) Source: Picouet 1999. Note: y (regression); R (squared correlation); N (rank). Figure 3.3 Evolution of the Yearly Volume Loss in the Inland Delta from 1955 to 1990 100 Volume at Ké Macina (upstream) 80 Volume at Diré (downstream) ) loss 3 60 (km Volume 40 Volume 20 0 1955 1960 1965 1970 1975 1980 1985 1990 Source: Olivry and others 1995. Note: This volume loss corresponds to the difference between the upstream volume (at Ké Macina) and the corresponding downstream volume (at Diré). THE NIGER RIVER BASIN'S WATER RESOURCES 39 Table 3.4 Average Values of Rainfall and Evaporation in the Inland Delta for Wet Periods and Dry Periods millimeters May June July Aug. Sept. Oct. Nov. Dec. Jan. Feb. March April Year Pw 17 58 94 190 92 26 0 3 1 0 4 6 490 Pd 13 50 92 97 65 8 2 0 0 0 0 3 330 Ew 220 210 200 160 165 185 180 160 165 185 210 220 2,260 Ed 240 220 210 180 170 195 180 160 170 190 215 230 2,360 Source: Olivry and others 1995. Note: P (rainfall); E (evaporation); w (wet periods); d (dry periods). Figure 3.3 illustrates the difference between the annual volume in the Inland Delta from Ké Macina to the outlet at Diré. In an average year, 60 cubic kilometers arrive from upstream and 30 cubic kilometers are lost by evapo- transpiration, corresponding to the extent of the flooded area in this reach, which can vary from 5,000 square kilometers to more than 30,000 square kilometers from the driest to the wettest years. Using information from table 3.4, figure 3.4 confirms the significance of water losses in the Inland Figure 3.4 A Comparison of Mean Monthly Volume Losses in the Inland Delta for Representative Dry and Wet Years 14 Wet Years (1962­66) 12 Dry Years (1982­86) 10 ) 8 3 (km 6 4 Volume 2 0 2 4 May June July Aug. Sept. Oct. Nov. Dec. Jan. Feb. March April Hydrological year Source: Olivry and others 1995. Note: From December, negative values indicate the restoration to the system from some of the waters stored in the floodplains. 40 THE NIGER RIVER BASIN: A VISION FOR SUSTAINABLE MANAGEMENT Figure 3.5 A Comparison of Two Hydrographs on Inflow (Ké Macina Douna) and Outflow (Diré) for Two Contrasting Years (1992 to 1993 and 1994 to 1995) 8,000 Inflow 6,000 Outflow Net losses/gains 4,000 s/ 3 Arrival of flood m 2,000 1992­93 Restitution flow y 0 ailD 2,000 Input and losses 4,000 6,000 May June July Aug. Sept. Oct. Nov. Dec. Jan. Feb. March April May 8,000 Inflow 6,000 Outflow Net losses/gains 4,000 s/ Arrival of flood 3 Restitution 1994­95 m 2,000 flow y 0 ailD 2,000 4,000 Input and losses 6,000 May June July Aug. Sept. Oct. Nov. Dec. Jan. Feb. March April May Source: Olivry and others 1995. Delta by contrasting the mean monthly volume losses for representative wet and dry years. This is further substantiated in the hydrographs of inputs and outflows from the Inland Delta for two contrasting years (figure 3.5). The changes in surface area in the Inland Delta have been confirmed by THE NIGER RIVER BASIN'S WATER RESOURCES 41 satellite imagery on the United States National Oceanic and Atmospheric Administration's Advanced Very High Resolution Radiometer (NOAA- AVHRR) (see appendix 1, map 15; Mariko and others 2000). Table 3.4 pre- sents the amount of rainfall and evaporation calculated for the Inland Delta in wet and dry periods, based on climate data from Mopti, Timbuktu, Diré, and Niafunke. Flooding in the Inland Delta Another characteristic of Inland Delta hydrology is the cushion it provides during the annual floods by slowing the pace of the flow, which spreads out in both space and time. The larger the flood, the more the flow spreads out over the space of the floodplain, and the longer it takes to spread out over time, with maximum decreases in flow downstream appearing later in the season, as illustrated for several monitoring sites for the entire Inland Delta (figures 3.6 and 3.7). In general, the peak flow period that arrives in September is delayed as it spreads, exiting the Delta three months later. A phase of receding water extends into February. The downstream impact of flooding on the Middle Niger is such that during a dry year the maxi- mum flow arrives in Niamey in mid-December, whereas in a wet year the maximum flow is not seen until the end of January or early February. Figure 3.6 Hydrographs Illustrating Buffering from Upstream to Downstream for the 1992 to 1993 Hydrologic Year 5,000 4,500 Ké Macina Douna 4,000 Nantaka 3,500 Akka /s) 3 3,000 Diré (m 2,500 flow 2,000 Daily1,500 1,000 500 0 May June July Aug. Sept. Oct. Nov. Dec. Jan. Feb. March April Source: Olivry 2002. 42 THE NIGER RIVER BASIN: A VISION FOR SUSTAINABLE MANAGEMENT Figure 3.7 Hydrographs Illustrating Buffering from Upstream to Downstream for the 1994 to 1995 Hydrologic Year 5,000 4,500 Ké Macina Douna 4,000 Nantaka 3,500 Akka /s) 3 3,000 Diré (m 2,500 flow 2,000 Daily1,500 1,000 500 0 May June July Aug. Sept. Oct. Nov. Dec. Jan. Feb. March April Source: Olivry 2002. The Middle Niger Downstream from the Inland Delta is the beginning of the middle reach (Malian-Nigerien and Beninese-Nigerien, and its right-bank tributaries), where the Niger changes course toward the southeast at Tossaye-Bourem without receiving any additional inflow. At Niamey, the maximum flows are usually twofold: a first wet seasonal peak flow and an upstream dry seasonal peak flow. The first high-water discharge, known as the white flood, occurs soon after the local rainy season in September; a second rise-- the black flood begins in December--with the arrival of the delayed flood from upstream. May and June are the low-water months in the Middle Niger. The first tributary in this reach, the Gorouol, comes from Burkina Faso. The Gorouol contributes, in an average year, 0.1 cubic kilometer for a water- shed of 45,000 square kilometers (0.07 liter per second per square kilome- ter, or 22 millimeters of runoff), which is equivalent to a day's worth of evaporation in the Inland Delta. Before approaching Niamey, there are three tributaries from Burkina Faso that contribute about 1 cubic kilometer in an average year. In this middle reach, the river system changes very little, except in September when the semiarid tributaries flood. The first flood peak reinforces the Niger River's flow by 5 percent to 20 percent. Historically, THE NIGER RIVER BASIN'S WATER RESOURCES 43 Figure 3.8 Hydrographs for Eight Years (1994 to 2002) at Niamey Illustrating the Two Flooding Phases in the Middle Niger 2,500 2004­5 2003­4 2,000 2002­3 1994­95 1984­85 s) 1,500 3 (m Flows1,000 500 0 June July Aug. Sept. Oct. Nov. Dec. Jan. Feb. March April May Source: WHYCOS-WMO/CIP-NBA (database). the average flow at Niamey was 1,020 cubic meters per second, but over the past 20 years it has been only 670 cubic meters per second, or two-thirds of the previous average. The maximum annual average was 1,840 cubic meters per second. Frequently, the floods caused by the input from the semi- arid tributaries in September are higher than the delayed flood from upstream. Low-water flows have persisted since the 1970s, and the Niger River even ceased flowing in 1985. Figure 3.8 shows annual (1994­2002) hydrographs at Niamey, beginning with low flows in July, for which the first maximum floods correspond to the nearby Burkina Faso tributaries, whereas the second maximum corresponds to the delayed flood of the Upper Niger from December to February. From Niamey to the border with Nigeria, the river gains 20 percent of its flow from right-bank tributaries coming from Benin: the Mekrou, the Alibori, and the Sota. The total annual runoff for these watercourses is on average 100 millimeters, but with significant interannual irregularity: 10-year mean annual runoff figures for dry and wet periods range from 40 mil- limeters to more than 200 millimeters (Le Barbe and others 1990). At Malanville, the annual flow volume was an average of 36 cubic kilometers, or 1,140 cubic meters per second (over 35 years), although the interan- nual flow has dropped to 800 cubic meters per second since the 1980s. The floodwaters from the Benin tributaries arrive in July, bringing sustained 44 THE NIGER RIVER BASIN: A VISION FOR SUSTAINABLE MANAGEMENT low-water flows greater than the flows that arrive from Niamey. The black floods and white floods are of equal average values (2,200 cubic meters per second). The white flood 10-year frequency is estimated at 2,800 cubic meters per second. The Nigerian Stretch of the Middle Niger and Its Left-Bank Tributaries In Nigeria, the Niger River continues to grow with the contributions from its rainfed tributaries. Downstream from the Sokoto on the left bank, which drains a partially semiarid, partially tropical, basin upstream of the Kainji Dam, the average annual flow is significantly increased by other more south- ern contributors. At Jebba, the Niger has a long-term mean annual flow of 1,600 cubic meters per second, although this has dropped to an average of 950 cubic meters per second over the past 15 years. After receiving the Kaduna (watershed of 65,500 square kilometers) with a flow of 600 cubic meters per second (and floods of 3,000 cubic meters per second, on average), the Niger flows to Baro. Over the period 1914­60, the average flow was 2,500 cubic meters per second, or a flow of 79 cubic kilo- meters for a 730,000-square-kilometer watershed at Baro. The annual max- imum flow reaches 9,000 cubic meters per second and the 10-year flood flow reaches 12,000 cubic meters per second. As at Koulikoro, the hydro- graph peaks with a maximum in September for the white flood, whereas the black flood is muted but still noticeable because the low flows are sus- tained from January to May at a level of 1,500­2,000 cubic meters per second. The Benue Basin At Lokoja, the Benue River reinforces the Niger (appendix 1, map 6). On the Benue, there is only one high-water season. Because of the Benue's more southerly climatic location, this normally occurs from May to October-- earlier than on the Middle Niger. Over the period 1950­80, the Benue had an average flow at Garoua (Cameroon) of 350 cubic meters per second, of which 250 cubic meters per second was from the Lagdo Dam, measured at Riao, and 100 cubic meters per second from the Mayo Kebi (Northern Cameroon and Chad). Using intermittent data obtained since 1980, the aver- age flow at Garoua would be 330 cubic meters per second or an annual flow of 10.4 cubic kilometers. In normal conditions, floods could reach extraor- dinary maxima (6,000 cubic meters per second in 1948) at the end of August or September, but the median maximum is approximately 2,900 cubic meters per second. Low flow could be down to only tens of liters per second, in other words, almost no flow. Coming from Cameroon, the Benue receives inflow from the Faro tributary just before the Nigerian border (mean annual THE NIGER RIVER BASIN'S WATER RESOURCES 45 flow about 310 cubic meters per second), and contributes 22 cubic kilome- ters in an average year (of which only 1.6 cubic kilometers comes from Chad). The total runoff is 230 millimeters for a rainfall of 1,240 millimeters, giving a runoff coefficient of 18.6 percent (Olivry 1986). In Nigeria, there is an extensive network of tributaries that flow into the Niger River. First, on the right bank, comes the Gongola, with a mean annual flow of 200 cubic meters per second (maximum average flood approxi- mately 1,200 cubic meters per second), followed by the left-bank contribu- tions that come from much wetter mountainous areas (Cameroon ridges, Adamawa, and Jos Plateaus on the right bank) subject to a more southern transitional tropical climate. These tributaries--the Taraba, the Donga, and the Katsina Ala--have a total flow contribution of about 1,700 cubic meters per second in an average year, or 54 cubic kilometers for 63,500 square kilometers of basin surface area, giving a total annual runoff of 844 mil- limeters. Of this total, 14 cubic kilometers come from the northwestern sec- tion of Cameroon where the Niger River headwaters cover only 8,750 square kilometers of surface area, giving a mean annual runoff of about 1,600 mil- limeters from a mean rainfall of 2,600 millimeters (a very high runoff coef- ficient of 60 percent). Measured near their confluence with the Benue, the average flood flows are 1,800 cubic meters per second for the Taraba and the Donga, and 2,800 cubic meters per second for the Katsina Ala. At Makurdi, the Benue River is transformed, reaching a mean flow of 3,150 cubic meters per second (100 cubic kilometers per year) for a 305,000-square-kilometer watershed. Over the past 20 years, this annual flow has been maintained (at 97 cubic kilometers), indicating that the incidence of drought has been lower here than elsewhere in West Africa (except during the 1980s). The average absolute low flow is 240 cubic meters per second and the average annual flood flow reaches 12,000 cubic meters per second. At the confluence with the Niger, over the same period, the Benue has a mean annual flow of 3,400 cubic meters per second (107 cubic kilometers). The Lower Niger River and the Niger Delta After Lokoja, the Lower Niger River--with an average annual volume of 190 cubic kilometers--flows directly south toward the Niger Delta and the Gulf of Guinea. The Lower Niger has a high-water period that begins in May or June (caused by high rainfall in the Benue basin)--and a low-water period that is at least a month shorter, because the rains in the south start earlier. At the last monitoring station, Onitsha, river flows have increased to a total of 200 cubic kilometers per year. The compilation of data from Baro and Makurdi shows a progressive increase in flow in June­July, with maximum levels reached in October (the average annual maximum flow is 25,000 cubic meters per second), after which the flow recedes. This is 46 THE NIGER RIVER BASIN: A VISION FOR SUSTAINABLE MANAGEMENT followed by a slight rise in level, then a flow of 2,000­2,500 cubic meters per second, corresponding to the black flood, before a low flow in May of 1,500 cubic meters per second. The long-term flow data also show deficit periods, including the dry 1970s. From 1980 to 2000, the mean annual flow measured at Onitsha was only 4,720 cubic meters per second, with a volume of 149 cubic kilometers per year; and the lowest flow ever recorded at Onitsha was 109 cubic kilo- meters in 1984. The Niger Delta Rainfall in the Niger Delta is typically 2,700­3,000 millimeters per year over an area of 30,000 square kilometers and actual evaporation is about 1,000 mil- limeters per year; this means a total runoff of 1,700­2,000 millimeters--and an additional flow of 50­60 cubic kilometers--that is calculated for the water balance of the Niger system. A total of 250 cubic kilometers per year dis- charges into the Gulf of Guinea. The Niger River: A Country Perspective River flows in the various tributaries from the nine Niger Basin countries, based on observations made before 1960 and 1980­2004, are shown in table 3.5. In both periods, the contribution of the Benue is greater than that of the Niger at their confluence at Lokoja. Whereas the hydrographic and hydrologic characteristics of the major reaches of the Niger River are described above, characteristics specific to each country are summarized below: · Bordering the Niger River for about 140 kilometers, Benin provides about 3 cubic kilometers in an average year from the Mekrou, Alibori, and Sota tributaries originating in the Atakora Massif and Bourgou. · Burkina Faso's contribution to the river's flow is only 1 cubic kilometer in an average year. · Cameroon's flow contribution to the Donga, and especially the Katsina Ala, reaches 14 cubic kilometers in an average year. A total of 34 cubic kilometers, from Chad and Cameroon, arrive in Nigeria from the Benue, more than from the Middle Niger River itself. · Chad's contribution to the Benue is 1.6 cubic kilometers in a normal year; the Benue is the major tributary of the Niger River originating in Central Africa. · Côte d'Ivoire is estimated to add approximately 4 cubic kilometers in an average year to the flow toward the Niger River, based on runoff of 270 millimeters. Table 3.5 Average Annual Flow and Flow Volumes in the Niger and Benue Basins from the Headwaters to the Niger Delta, before 1960 and from 1980 to 2004 Flow Annual Annual Country Surface before Flow volume volume tributary and area 1960 1980­2004 before 1960 1980­2004 stations (km2) (m3/s) (m3/s) (km3) (km3) Niger River Guinea Tinkisso -- -- -- 220 160 Niandan -- -- -- 260 189 Milo -- -- -- 275 160 Siguiri Station 67,400 1,015 755 -- -- Sankarani 405 265 Mali Koulikoro Station 120,000 1,545 1,040 -- -- Côte d'Ivoire Bani -- -- -- 670 207 Burkina Faso Delta Inflow 222,000 2,195 1,247 -- -- Diré Station 330,000 1,110 750 -- -- Niger Niamey Station -- 1,020 670 -- -- Benin Malanville Station 440,000 1,140 800 Nigeria Yidere­Bode -- -- 820 -- -- Sokoto -- -- -- 200 100 Jebba Station 1,370 1,600 950 -- -- Kaduna 212 600 400 Baro 730,000 2,525 1,370 -- -- Benue River Cameroon Riao Station 27,600 280 212 -- -- Chad Mayo Kebi -- -- -- 100 80 Cameroon Garoua Station 64,000 375 308 -- -- Nigeria Gongola -- -- -- 200 120 Taraba -- -- -- 500 380 Donga -- -- -- 500 400 Cameroon Katsina -- -- -- 800 675 Nigeria Makurdi Station 305,000 3,150 2,380 -- -- Lokoja Station -- 3,400 2,500 -- -- Niger River Lokoja Station -- 3,000 1,600 -- -- Onitsha Station 1,100,000 7,000 4,570 -- -- Source: Rodier 1964. Note: -- not available. 48 THE NIGER RIVER BASIN: A VISION FOR SUSTAINABLE MANAGEMENT · Guinea remains the "water tower" of the Niger River, with a flow of 36 cubic kilometers in an average year supplied by the Upper Niger at Siguiri, together with the Sankarani tributary. · Mali, which has a complex water balance, in an average year receives 36 cubic kilometers from Guinea and 4 cubic kilometers from Côte d'Ivoire, then adds 5 cubic kilometers to the river from the Sankarani and various tributaries upstream of Koulikoro and another 10 cubic kilo- meters from the Bani and minor tributaries of the Dogon region. However, Mali loses 28 to 30 cubic kilometers, 25 cubic kilometers of which is in the Inland Delta through evaporation, before the river reaches Niger. · Niger's contribution to the river flow is negligible or, more precisely, negative (evaporation). The annual flow increases at Gaya are a result of inflows from Benin. · In Nigeria, of the 182 cubic kilometers that flow through the city of Onitsha in an average year, only 65 cubic kilometers come from upstream coun- tries, with almost two-thirds of the flow produced within the country itself. Transport of Suspended and Dissolved Solids The total suspended solids (TSS) are the particles that are suspended in water. The total dissolved solids (TDS) are the materials that are dissolved in water. Suspended Solids This section looks at transport of TSS as it affects the Upper Basin, Inland Delta, Middle and Lower Niger, and navigation on the Niger River. Sediments can be transported by water either in suspension, thereby becom- ing a part of the water flow because they travel at the same speed as the water, or by being displaced by the current, either by saltation or as bed load at much reduced speeds. Suspended solids tend to be fine sand, silt, and clay, whereas bed load includes heavier sand and larger elements. The amount of solids transported in suspension is more significant than bed load. It is estimated that bed load transport for a system such as that of the Niger River is less than 5 percent of the suspended load. Upper Basin. The TSS transported in the Niger River result from watershed erosion of streambeds and banks. The annual TSS load carried by the Upper Niger varies between 0.7 million ton and 2 million tons, depending on river flow. Generally, the Upper Niger River has a low sediment load, with average annual TSS concentrations of about 20­30 milligrams per liter, rising to 50 milligrams per liter when crossing dry areas downstream. The Bani River's suspended sediment load is higher, at approximately THE NIGER RIVER BASIN'S WATER RESOURCES 49 50­75 milligrams per liter. Seasonal variations are significant and, with the first floods of the season transporting more sediment, concentrations can reach up to 150­200 milligrams per liter in May­June (300 milligrams per liter on the Bani), dropping to less than 5 milligrams per liter at low flow (figure 3.9). The annual discharge of TSS from 1991 to 1998 was recorded at monitoring stations in the Upper Niger Basin (table 3.6). Figure 3.9 Flow and Concentrations of TSS for the Niger at Koulikoro [a] and the Bani at Douna [b] 250 1,000 Flows (right axis) TSS (left axis) 200 800 150 600 m /s 3 mg/l 100 400 50 200 0 0 June July Aug. Sept. Oct. Nov. Dec. Jan. 1990 (a) 160 3,500 140 3,000 120 2,500 100 2,000 m 80 /s 3 mg/l 1,500 60 1,000 40 20 500 0 0 June July Aug. Sept. Oct. Nov. Dec. Jan. 1991 (b) Source: Gourcy 1994. 50 THE NIGER RIVER BASIN: A VISION FOR SUSTAINABLE MANAGEMENT Table 3.6 Annual Discharge of TSS in the Upper Niger (Banankoro, Koulikoro, and Ké Macina) and the Bani (Douna) 1991­92 1992­93 1993­94 1994­95 1995­96 1996­97 1997­98 Banankoro Flow (103 t/yr) 338 411 467 800 862 596 479 Flow (m/s) 531 521 521 1,070 977 825 729 TSS (mg/l) 20.1 25.1 28.4 23.7 27.9 22.9 20.8 Ts (t/km2/yr) 4.8 5.8 6.6 11.3 12.1 8.4 6.7 Koulikoro Flow (103 t/yr) 607 593 665 1,296 1,014 960 986 Flow (m3/s) 767 775 732 1,480 1,310 1,050 1,019 TSS (mg/l) 25.1 24.3 28.8 27.8 24.5 29.0 30.7 Ts (t/km2/yr) 5.1 4.9 5.5 10.8 8.4 8.0 8.2 Ké Macina Flow (103 t/yr) -- 715 1,028 1,974 1,701 1,223 1,139 Flow (m3/s) -- 681 647 1,320 1,180 929 911 TSS (mg/l) -- 33.3 50.4 47.4 45.7 41.8 39.6 Ts (t/km2/yr) -- 5.1 7.3 14.0 12.1 8.7 8.1 Douna Flow (103 t/yr) 257 229 315 729 389 422 448 Flow (m3/s) 190 139 135 459 224 200 202 TSS (mg/l) 42.8 52.3 74.1 50.3 55.1 66.9 70.3 Ts (t/km2/yr) 2.5 2.3 3.1 7.2 3.8 4.2 4.4 Source: Olivry and others 1998. Note: -- not available; Ts (transport spécifique) is the annual discharge of TSS divided by the basin area. Analysis of the seasonal distribution of TSS shows that, regardless of where the monitoring station is on the river, more than 70 percent of the annual transport occurs in the August­October period of high river flow. Over this period, the significant increase in sediment transport is accom- panied by an equally significant decrease in sediment concentration. The monthly average sediment transport figures in August and September are similar. Despite the heavy TSS concentrations reached in the initial erosion phase during July, these concentrations account for only about 12 percent of the annual sediment transport. Inland Delta. TSS levels decline as the river passes through the Inland Delta, with significant settling in the central lakes and in Lake Debo, notably upstream of Akka. Some increases in TSS occur in the downstream part of the Inland Delta, with the appearance of the first dune belts upstream of Diré. The annual sediment transport flows at the Inland Delta THE NIGER RIVER BASIN'S WATER RESOURCES 51 Table 3.7 Average Annual Flow and Discharge of TSS at Akka and Diré in the Inland Delta 1992­93 1993­94 1994­95 1995­96 1996­97 1997­98 Akka Flow (103 t/yr) 591 654 1,033 989 897 832 Flow (m3/s) 577 571 1,209 892 753 739 TSS (mg/l) 32.5 36.3 27.1 35.2 37.8 35.7 Diré Flow (103 t/yr) 784 766 1,487 1,183 962 887a Flow (m3/s) 574 563 1,084 866 745 729a TSS (mg/l) 43.3 43.2 43.5 43.4 41.0 38.6a Source: Picouet 1999. a. Flow estimated in 1998 by correlation between stations. Table 3.8 Assessment of the Average TSS in the Inland Delta from 1992 to 1998 thousands of tons Regions of the Inland Delta 1992­93 1993­94 1994­95 1995­96 1996­97 1997­98 At entry to 944 1,343 2,703 2,090 1,645 1,587 Inland Deltaa Lake Debo Outletb 696 747 1,250 1,162 1,032 957 Upstream Delta 248 596 1,453 928 613 630 balance Delta Outletc 784 766 1,487 1,183 962 887 Downstream Delta 88 19 237 21 70 71 balance Total balance 160 577 1,216 907 683 700 Source: Picouet 1999. a. Total flow from the two inlets (Ké Macina and Douana). b. Total flow of the three outlets leaving Lake Debo (Akka, Awoye, and Korientze). c. Flow at the single delta outlet (Diré). stations for the hydrologic years between 1992 and 1998 are presented in table 3.7 of Akka and Diré (Picouet 1999). As with the stations in the Upper Niger, the variations in suspended sediment transport volumes are related directly to river flows. Table 3.8 provides the range of the annual TSS flow balance in different parts of the Inland Delta. The overall balance 52 THE NIGER RIVER BASIN: A VISION FOR SUSTAINABLE MANAGEMENT shows that 0.16 to 1.2 million tons of sediment were deposited within the Inland Delta per year during the observation period (or 17 percent to 45 percent of the TSS entering the Inland Delta). The Middle and Lower Niger. After crossing the Inland Delta, the Middle Niger River's TSS concentrations tend to increase as a result of by harmattan dust and windblown sand coming from the dunes along the riverbanks. At Tossaye, TSS levels over 100 milligrams per liter can be expected. This trend extends for the entire reach of the Middle Niger. Very erosive floods from the semiarid tributaries in Burkina Faso add suspended solids to these TSS concentrations. For example, the Gorouol, at Dolbel, has an average TSS of 750 milligrams per liter for a flow of 9 cubic meters per second (1976­83, with five months without flow) and monthly concentrations exceeding 1,000 milligrams per liter. The Gorouol transported an average of 180,000 tons in the observation period, whereas the figure for Kandadji was 1.64 million tons. At Niamey, TSS concentrations again show an increase; data include other years of observation and are not directly comparable to the data for Kandadji, but they show the significance of the Burkina Faso tributaries, the Dargol and Sirba. Over the three years of measurement by Gallaire (1995) at the Niamey station, the annual TSS load was 3.5 million tons, which cor- responds to the lowest value of TSS measured at this station. Figure 3.10 shows the lag between peak TSS and monthly flows at Kandadji station. A significant level of suspended sediment transport by semiarid or dry tropical tributaries also is found in Nigeria, for example, from the Sokoto and Gongola; and on the Benue, from the tributaries of northern Cameroon, where concentrations greater than 10 grams per liter have been measured at the beginning of the season (Nouvelot 1969; Olivry 1978). TSS loads of the Middle Niger, given the tropical system's tributaries, its violent floods, and its strong erosive power, increase considerably down- stream. The Benue has similar characteristics. Although these loads are not comparable to those of some waterways of semiarid areas (such as in North Africa), high TSS loads (the white flood) have begun to pose a silting prob- lem, and bottom dredging must be planned for dams. According to Meybeck (1984) and Milliman and Syvitski (1992), the Niger transports 40 million tons of sediment per year through Nigeria, as measured at Onitsha. Based on a flow of 154 cubic kilometers in heavy deficit years, the average annual concentration is 260 milligrams per liter. The flow of sedi- ment is 30 percent higher than that of the Congo River, even though the Congo River carries seven times more water to the ocean than the Niger carries. Impacts on Navigation. The difficulties encountered in river navigation on the Middle and Upper Niger and the upper Benue over the past 30 years give the impression that bed load transport has increased, creating THE NIGER RIVER BASIN'S WATER RESOURCES 53 Figure 3.10 Hydrograph of Average Monthly Changes in TSS at Kandadji 2,000 400 300 1,000 s 3 1,000 200 m t 100 0 0 June July Aug. Sept. Oct. Nov. Dec. Jan. Feb. March April May TSS Flow (right axis) Flow (left axis) Source: Gallaire 1995. sandbars and silting up previously navigable stretches. In the Inland Delta and other river areas experiencing progressive narrowing of secondary branches, the drought that dried these channels has not allowed the annual "rinsing" of the seasonal barriers created by deposits of windblown sand and dunes. It will take several years of heavy flooding to reestablish previous water circulation, particularly in the lower part of the Inland Delta. This may lead to the assumption that more sand is being transported, because sandbanks are now seen for six months a year instead of three, and navigation is possible for only four months instead of six. In fact, it is because of low flood levels that the water channel used for navigation is narrower. Dissolved Solids This section looks at transport of TDS as it affects the Upper Basin, Inland Delta, and Middle and Lower Niger. Upper Basin. For the Niger's Upper Basin, TDS transport is 30 percent to 40 percent greater than TSS transport. Between 1.3 and 2.3 million tons of dissolved solids are exported annually to the Inland Delta, depending on river flows; 72 percent to 85 percent of this flow is contributed by the Niger (Ké Macina station) and the remainder by the Bani. This represents a 54 THE NIGER RIVER BASIN: A VISION FOR SUSTAINABLE MANAGEMENT specific flow of 4.7­9.7 tons per square kilometer of catchment area per year. The specific flow is very low at the Douna station on the Bani (from 1.7­6.5 tons per square kilometer per year), compared with that observed at Ké Macina on the Niger (6.2­12.3 tons per square kilometer per year). This latter specific flow is even lower that those calculated at the Niger River stations upstream of Banankoro (8.2­19.6 tons per square kilometer per year) and Koulikoro (8.6­17.5 tons per square kilometer per year). Inland Delta. The overall transport balance shows that 2 to 5 million tons of solids enter the Inland Delta, half of which are dissolved solids and half of which are suspended solids. The suspended solids portion increases as it travels downstream, where unprotected soils are subject to higher erosion. The TDS difference between stations, and for a single station over different years, is linked to the intensity of drainage and rainfall. The annual balance between entrance and exit of dissolved solids flow over the two largest parts of the Delta (upper and lower) is shown for two contrasting, consec- utive hydrologic years, 1993­94 and 1994­95, in table 3.9. A comparison of TSS and TDS for the Upper Basin and the Inland Delta is provided in figure 3.11. Table 3.10 gives an overview of average TDS discharge for 1993­94 and 1994­95. Middle and Lower Niger. The dissolved solids load shows very little variation in concentrations from upstream to downstream. Table 3.11 gives the average concentrations of major ions over the course of the river. Milliman and Syvitski (1992) cite a value of 59 milligrams per liter, or a TDS load of 9 million tons for a low-water flow year and 10 million tons in Table 3.9 Average Monthly TSS Concentrations in the Middle Niger grams per cubic meter June July Aug. Sept. Oct. Nov. Dec. Jan. Feb. March April May Gorouol at 1,265 868 549 475 604 345 -- -- -- -- -- 1,010 Dolbel (1976­83) Niger River at 151 337 229 139 93 46 32 38 46 60 58 66 Kandadji (1976­83) Niger River at 184 422 415 356 364 163 108 91.5 87.3 75.3 78 125 Niamey (1984­86) Source: Picouet 1999. Note: -- not available. THE NIGER RIVER BASIN'S WATER RESOURCES 55 Table 3.10 Average Annual Discharge of TDS in the Inland Delta for Two Consecutive Years 1993­94 1994­95 Volume TDS flow Volume TDS flow (km3/year) (103 t/year) (km3/year) (103 t/year) At entry to Inland Delta 24.7 1,177 56.1 2,367 Lake Debo Outlet 20.8 932 45.7 2,295 Upstream Delta loss 4.2 245 10.4 73 Diré Outlet 17.8 829 34.2 1,734 Downstream Delta loss 2.7 103 11.5 560 Total loss 6.9 348 21.9 663 Source: Picouet 1999. Figure 3.11 Assessment of the Annual Average Discharge (1992­97) for TDS and TSS from the Upper Niger and Bani Watersheds to the Inland Delta Flow in 103 t/yr KE MACINA 1271 1328 TSS TDS Ségou Bani Niger KOULIKORO DOUNA Bamako Upper Niger Watershed 353 390 (141,000 km2 at Ké Macina) 856 1451 BANANKORO 579 974 Bani Watershed (102,000 km2 at Douna) Main stations Main cities 0 200 km Source: Picouet 1999. 56 THE NIGER RIVER BASIN: A VISION FOR SUSTAINABLE MANAGEMENT Table 3.11 Average Concentration of Major Ions in the Niger River in Mali and at Onitsha milligrams per liter Major ion Calcium Magnesium Sodium Potassium Chlorine Sulfate Carbon Total Niger Ké Macina 2.4 1.1 3.0 1.5 1.0 -- 22.3 31.3 Bani 2.8 1.2 2.6 2.1 0.6 -- 23.8 33.1 Benue at Garouaa 5.6 1.9 3.5 2.0 -- -- 30.5 43.5 Onitsha 4.1 2.6 3.5 2.4 1.3 1.0 36.0 50.9 Sources: Picouet 1999 (Mali); Meybeck 1984 (Onitsha). a. Specific analysis in December 1974. Note: -- not available. an average year reaching the ocean (flow of 182 cubic kilometers, which is four times less than the TSS load). The relative level of total organic carbon (TOC; >0.45 µg, taken in 1996­7 from five upstream Niger River Basin stations, varies from 1.3 percent to 20.45 percent of particle transport. Half of the TOC values were less than 4.95 percent and only 25 percent were greater than 7.1 percent. The higher values are found during flood recession and in low-flow conditions. Concentrations, in milligrams per liter, are most often between 0.1­1.85 (90 percent of the values). On savanna and forested landscapes of the Middle and Lower Niger, the maximum percentage of TOC runoff, which can exceed 30 percent, is seen when TSS concentrations are lower. The annual average is 6 percent to 8 percent of TSS contribution, or approximately 1.5 milligrams per liter. Water Quality The degradation of water quality is a significant problem for the Niger. The growth of large cities along the river's banks has not been accompanied by development of wastewater collection and treatment plants, whether for domestic or industrial wastewater. Picouet (1999) establishes a water sam- pling protocol for the soil and climate conditions found in Africa that allows him to analyze very low concentrations (in parts per billion) of trace ele- ments in the waters of the Upper Niger. The enrichment factor calculated for these trace elements, compared with international standards, allows a pre- liminary estimate of contamination from anthropogenic sources. The results show that at any of the stations of the upper basin, titanium, aluminum, iron, zirconium, yttrium, strontium, lead, uranium, and vanadium can be considered as earth elements, coming from the weathering of silicate rocks. These elements are correlated to one other and to TSS. Enrichment factors THE NIGER RIVER BASIN'S WATER RESOURCES 57 for strontium are very significant at Banankoro, then drop off all the way to Ké Macina. They are the weakest at Douna, which suggests a possible addi- tion of antimony, an element used in metallurgy and other production. Other enrichment factors do not show significant contamination from anthro- pogenic sources, whether in rainwater or in river water, although water at Koulikoro appears to be more enriched than the water upstream at Banankoro. Koulikoro is located downstream of the city of Bamako, where the main industries responsible for discharging metallic elements can be found (such as tanneries, dye works, galvanizing operations, and textile industries). Fertilizer use also has an impact on water quality. The impact of cotton farming in southern Mali on wells, pasture, and surface water in the Bani watershed was studied in the 1990s. Traces of pesticides were found, but not in significant amounts. Nitrates, nitrites, phosphates, and ammonia were consistently present at several sites, sometimes over the maximum allowed limits (Bonnefoy 1998). In the past 40 years, Nigeria has experienced intense exploitation of its petroleum resources, and currently produces 2 million barrels per day from three primary refineries in Port Harcourt, Warri, and the Delta. Petroleum development has contributed to several environmental problems, and in particular those pertaining to water resources. In the Delta, these environ- mental problems are usually caused by accidental pollution and by illegal siphoning. Studies have indicated that more than 2 million barrels have been spilled into the environment from 1972 to 1982. In addition to petro- leum development, the exploitation of coal, iron, gold, and other mineral resources is an environmental threat in the Basin. Closing Comments on the Technical Chapters In the preceding chapters, the authors have sought to provide not only a baseline understanding, but also an insight into the unique characteristics and distinctive geographic and geological setting of this "river of rivers" in West Africa. The Niger River is and will continue to be a vital resource to all the people in the Basin. The nine Niger Basin countries, with their specific geo- graphic characteristics and hydrologic contributions, share in the resources of the river. Management of these shared resources calls for a common under- standing of and consensus on sustainable use of the Basin's resources. A common understanding of the entire river system will provide a platform for dialogue and cooperative river basin management, leading to shared oppor- tunities and benefits. The final chapter will explore the criteria needed for suc- cess in cooperative development of the Niger River Basin. 4 Cooperative Development of the Niger River Basin: Criteria for Success Promoting Development and Poverty Reduction It is a basic premise of river basin management that managing the river as a system yields optimal benefits. In the case of the Niger River, this could mean more water, more food, more power, more transport, and so on. Optimized management of any river is difficult, primarily due to the need to recognize so many different interests; with an international river this is par- ticularly difficult, but much can still be done to move in this direction. The nine Niger River Basin countries are among the poorest countries in the world, and everything possible must be done to improve the lives of the peoples of the Basin. Four of the nine Basin countries are among the bottom 20 countries on the WDI scale, while on the UNDP HDI, seven countries are among the bottom 20. The need for development and invest- ment in the region is evident, and the Niger River holds tremendous poten- tial; this is the reason for cooperation. Development opportunities in the Niger Basin are wide ranging. Some of these opportunities, such as in power, irrigation, and navigation, are directly linked to the river. Once cooperative investments have been made in the development of the water resources, trust and cooperation will grow between the countries, and many other benefits will accrue, include those "beyond the river," such as com- munication investments, increased trade, enhanced flows of labor and ideas--that is, an enhanced regional integration of the countries of the Basin. Specific investment opportunities identified by the countries include, but are not limited to: · Food production. Irrigation potential estimated at 2.5 million hectares, of which only 0.5 million have been developed · Energy production. Hydropower generation estimated at 30,000 gigawatt hours per year in the Niger River and its tributaries, of which only 6,000 gigawatt hours have been developed 58 COOPERATIVE DEVELOPMENT OF THE NIGER RIVER BASIN 59 · Access to markets. Transportation facilities, including navigation potential of 3,000 kilometers, of which only 600 kilometers are currently navigable · Environment. Enhanced environmental management, especially in the Fouta Djallon watershed and the Inland Delta, which will lead to signi- ficant benefits for the overall sustainability of the water resources and the Basin · Flood and drought mitigation. Enhanced flood management, early warn- ing systems, and storage options, which will help reduce the devastating impacts of floods and help further mitigate the impacts of droughts · Livestock and fisheries. Significant livestock and fisheries potential, currently not commercially developed but highly reliant on predictable water availability · Ecotourism, which has considerable potential and has yet to be explored From Unilateral to Cooperative Development Getting beyond the national agenda is not easy . . . As is to be expected, most countries plan large investments at the national level. When dealing with a shared river basin, and in the absence of an effective basin organization, most countries will plan on a unilateral basis. In some river basins, member states have rushed to "get facts on the ground" through infrastructure projects, seeking to acquire rights ahead of any neighboring states doing the same. In the absence of a cooperative agenda to which countries have committed and which clearly assigns benefits to each member state, the pursuit of unilateral development will most likely lead to lose-lose outcomes, the potential consequences of which include increased tension and insecurity between member states, and lost opportunities for regional cooperation and integration. For many years, the trend in each of the Niger Basin countries has been toward unilateral development of the river's resources. From the position of each nation state, this makes perfect sense, particularly given the lack of a strong regional river basin institution through which cooperative developments could be leveraged, promoted, and instituted. . . . But it is the only way to secure sustainable win-win benefits. In the Niger River Basin, where water scarcity and flow variability are always causes for concern, the only option for sustainability of the water resources, optimal utilization, and good member relationships is to pursue the path of coordinated, cooperative water resources development. The challenge facing the countries of the Basin is to find ways in which the river's development potential can be realized. With an empowered, enabled, and relevant river basin organization in place, attuned to its constituencies and respected as an institution that can broker major development investments, 60 THE NIGER RIVER BASIN: A VISION FOR SUSTAINABLE MANAGEMENT the nine countries have an opportunity to move a significant, common development agenda forward, to reduce poverty, promote regional cooperation and integration, and enhance the lives of the 100 million people who live in the Niger River Basin. Moving from a river basin master plan . . . A common approach to river basin development has been to develop "river basin master plans." This makes sense, because such a comprehensive approach facilitates elabora- tion of a broad and holistic development plan and provides an overall blueprint for the potential and planned water resources development in the Basin. Donors have at times funded these plans on behalf of river basin organizations in developing countries. Their development is costly, involving many studies and considerable time to complete. Such an approach has merit for a small and relatively simple basin within a nation state. For the Niger River Basin, however--whose watershed encompasses nine countries with a wide-ranging set of investment needs, priorities, and abilities--this approach is of limited real value, because it takes little account of the political and economic reality. Investments will inevitably be driven by a variety of factors, including local and national priorities, diplomacy, political compromise, availability of and access to investment finance, and, perhaps most important, the extent of broad ownership of, and commitment to, defined development priorities. . . . Toward a more dynamic shared vision of the Niger River Basin. A more dynamic approach to large river basin development will need to be both more pragmatic and attainable. Although detailed analysis and design potential developed through master plans are helpful, they do not contribute directly to building the community of interest and political constituency among and within the member states that is the key to moving cooperative developments forward on Africa's large shared river systems. In several river basins in Africa (and beyond), concerned countries have embarked on the definition of a Shared Vision that encompasses their views of how shared water resources can help in the struggle against poverty, against environmental degradation, for peace, and for regional cooperation and integration. The countries of the Niger Basin have recently endorsed development of a Shared Vision process that lays out cooperative actions through which needs and priorities will be defined and through which management, development, and investment actions will be identified. Laying the Institutional Foundation for Cooperation The institutional mandate and its renewal. The 1980 Niger Basin Convention defines the basic scope and mandate of the NBA. This legal framework was established to promote cooperation between the member states and COOPERATIVE DEVELOPMENT OF THE NIGER RIVER BASIN 61 to ensure integrated development in all areas as part of development of its resources, particularly in the areas of energy, water, agriculture, forestry, transportation and communication, and industry. The Convention provides a powerful platform for the NBA to promote, facilitate, and coordinate river basin development among the Basin countries, empower- ing the institution to play a strong, substantive, and important role in assisting them in their development of the Basin. However, the NBA underwent a crisis during the early 1990s, engaging in a variety of projects and activities that may have allowed for institutional survival but that distanced the institution from its core mandate to manage and develop the Basin. In 2002, the NBA Summit of Heads of State met in Abuja and reviewed the performance of the NBA, agreeing to set the organization on a renewed path toward identifying relevant and strategic priorities, through a Shared Vision process supported by a Sustainable Development Action Program (SDAP), to serve the member countries. The Summit of Heads of State expressed clear expectations of the institution. At the level of the river basin. During the 1990s, the NBA lost its basic legiti- macy, relevance, and constituency, the three key requirements for the viability of the institution. Other important factors, such as capacity and financial viability, are often a result of these three prerequisites. · Legitimacy of the institution is defined by its legal and juridical basis but is also a function of how the institution is perceived by those whom it is intended to serve, its credibility among stakeholders, the level of com- petency of its staff, and the transparency of its governance. · The relevance of the institution is similarly significant. Does the institution address the real issues faced by the nations in its basin, and thereby serve its constituency? Or is the institution preoccupied with marginal projects or products that do not meet the mainstream development goals set by the countries that are the "shareholders" of the institution? · It is the "shareholders" of the institution, the constituency, who will be the ultimate judge of whether the river basin organization has achieved legitimacy and relevance. Unless the constituency sees the NBAas directly relevant to domestic development priorities, it is unlikely to place real value on the institution. A practical consequence will be that the annual budgets of the institution are left unpaid and it will become increasingly irrelevant to national priorities, initiating a downward spiral that is exac- erbated as the institution, to maintain itself, seeks resources from a vari- ety of sources (including donors), involving activities that no longer respect the institution's mandate. The degree to which the NBA can recapture both legitimacy and relevance will largely determine whether the institution will meet the expectations of its constituency. 62 THE NIGER RIVER BASIN: A VISION FOR SUSTAINABLE MANAGEMENT At the national level, river basin development is everyone's business. A clear factor for success at the national level is to ensure that the NBA's agenda is owned by many stakeholders. This includes the ministries of water resources and hydraulics as well as the ministries of finance, foreign affairs, energy, agriculture, transport, and environment. In addition, because river basin development is very much a local issue, local govern- ments, basin management agencies, farmers, and communities are equally important stakeholders. Identifying and empowering a champion. At the national level, therefore, it is important to have a strong champion and coordination mechanism for river basin management. Although "focal points" based in water or hydraulic ministries have an important role to play, they frequently do not have the ability to convene other ministries in key discussions on engagement, priorities, trade-offs, and commitments. A broad national constituency must have ownership of the agenda for national water resources management and development aspirations to be fulfilled on shared water resources. A strong national champion of river basin management--for example, the minister of water and hydraulics or an appointed senior official in the prime minister's office--will be needed to convene opposing interests, to formulate an agenda for engagement, and to forge alliances, both at home and abroad. The legal framework. An enabling legal framework that is reviewed and updated as needed can go a long way toward facilitating river basin cooperation. That said, a legal framework alone, however solid, cannot be relied on to achieve the institution's development goals. Although the architecture of the legal framework is important--because it provides the mandate and structure of the institution, and as such creates the vehicle with which the cooperation agenda can be driven--it is the driver of the vehicle who will define the path to legitimacy, relevance, and constituency. Subsidiary agreements may be needed at a later time. In view of the hydrolog- ical complexity of the Niger Basin, it is possible that subsidiary agreements among a subset of Basin countries will be required for specific river basin developments, which might not involve, or affect, all the Basin countries. For example, developments on the Niger River tributaries in Chad or Cameroon will have no impact on Guinea, Mali, or Niger and a subsidiary agreement between or among the involved and affected parties would therefore make sense. Such subsidiary agreements should of course fit within the framework of legal principles and agreements that exist at the level of the full river basin and to which the nine Basin countries have agreed. COOPERATIVE DEVELOPMENT OF THE NIGER RIVER BASIN 63 A Political Mandate: The Shared Vision and Sustainable Development Action Program Creating an enabling environment for cooperation . . . In Abuja in February 2002, the Niger Basin heads of state agreed to develop a management framework for the Basin through preparation of a Shared Vision and SDAP. The Shared Vision is an expression of the countries' commitment to promote a framework for enhancing cooperation and sharing benefits deriving from the Niger Basin's resources. The Shared Vision process encompasses several objectives. The first objective is political, to formulate a statement on sustainable development of the Niger Basin to be adopted by the Niger Basin heads of state. Such a statement must include commit- ments to, and goals for, cooperation that will lead to joint developments in the Basin. The second objective is operational, to prepare the SDAP for the Niger Basin. The SDAP is seen as an appropriate instrument to realize countries' commitment to address the challenges of the Basin. It will include an innovative planning and priority-setting approach to define the development opportunities in which the member countries can jointly participate. The Shared Vision's third objective is financial, to mobilize resources from both member countries and international donor partners to implement the SDAP. . . . Overseen by the Heads of State Summit. To facilitate this process and report on progress to Basin country decision makers, a supervision mechanism has been established. The Niger Basin Council of Ministers reports directly to the Heads of State Summit. The Council is comple- mented at the national level by National Steering Committees, whose role is to ensure country commitment to, ownership of, and engagement in the proposed decisions and actions that will form the basis for the planning and development agenda of the Niger River Basin. Making Cooperation Happen in the Niger River Basin Shared Vision: a phased approach. . . The Shared Vision process has two main phases. The first phase, nearing completion, includes preparation of national multisectoral studies to explore opportunities and constraints for joint developments in the Basin. Also during this phase, a series of consul- tations is being held with various stakeholders at the local, national, and regional levels, and with potential donors and sources of technical expertise. In order to develop regional capacity to implement the SDAP, the first phase also includes an institutional audit of the NBA. The goal of this audit is to enable the institution to reform and adapt itself to the challenges of realizing the Shared Vision. The second phase of the Shared 64 THE NIGER RIVER BASIN: A VISION FOR SUSTAINABLE MANAGEMENT Vision, building on the outcomes of the multisectoral studies, will consist of formulating SDAP actions at the Basin level and identifying specific joint development opportunities within the Basin. This phase of the Shared Vision also includes the creation of an institutional mechanism for the Basin countries to agree on priority actions, based on project location and potential for shared benefits. Sharing benefits and costs of cooperation. In determining system boundaries for assessment of costs and benefits, it is important to include the entire Basin and to identify all benefits, including those that may be beyond the immediate water resources investment. Environmental benefits (and costs) and direct benefits from water resources investment are potentially the easiest to identify, to cost, and to share. Other less tangible benefits include the reduction of costs that are intrinsic to the absence of coopera- tion on the river (due, for example, to suboptimal power and food produc- tion), as well as those benefits "beyond the river" that will derive from enhanced cooperation, trade, flow of communication, ideas, labor, and so on.9 Cooperation options. In West Africa, the experience of the Organisation la mise en valeur du fleure Sénégal (OMVS), the Basin's management organization, in co-owning and operating assets sets an important precedent for a form of cooperation that is extremely sophisticated. Consequently, other forms of cooperation may be viewed as "less worthy," but this would be a mistake. There are many degrees or types of coopera- tion on international river basins, with each type defined and shaped by the degree of geographic and hydrological complexity in the river basin, by history, economics, diplomacy, and politics. Figure 4.1 presents a schematic depiction of various types of cooperation in selected river basins. The Niger Basin states can engage at many levels. As engagement grows stronger, confidence and trust will also grow and a move along the contin- uum may be both facilitated and appropriate. The Niger Basin countries have committed to cooperation and moving from unilateral action toward enhanced coordination, collaboration, and possibly joint action, even inte- gration. The Shared Vision process and the SDAP will help to achieve these goals. Joint infrastructure: a primary source of benefits. The obvious form of cooper- ation is in investing in joint structures for the management of the river, such as in multipurpose storage and river regulation, which can enhance food and power production and lead to greater water security for the countries during drought or water-scarce years. Such investments would be in contrast to the history of unilaterally developed structures, and in contrast to plans for such structures, which meet national needs only and COOPERATIVE DEVELOPMENT OF THE NIGER RIVER BASIN 65 Figure 4.1 Examples of Types of River Basin Cooperation Types of Cooperation ­ some examples Indus Mekong Rhine Orange Senegal River Communication Information Convergence Joint Equity & sharing of national preparation joint Types of agenda of projects ownershipcooperation & investments Dispute Cooperation Continuum Integration Unilateral Coordination Collaboration Joint Action Action Source: Sadoff and Grey forthcoming. take no account of the needs of the Basin as a system, or of the Basin population as one community of interest. Debt sustainability: an incentive for cooperative investment. Some Niger River Basin countries are highly indebted and working hard to manage their debt sustainability. In this context, cooperation on jointly owned and jointly operated works becomes a relevant option. Although the pursuit of debt sustainability alone is an insufficient incentive to make cooperation work, it can, nevertheless, be a contributing catalyst for development of jointly owned assets. Decision-making tools. To enable the river basin organization to prioritize, plan, and determine optimum investments, the organization must have solid datasets and good river basin models that can facilitate objective analysis of impacts, costs, and benefits. The Niger Basin is in a good position in this regard, because it has one of Africa's best and most sophis- ticated basinwide hydrological monitoring systems. A next step is to develop tools through which hydrological and economic modeling could be carried out to identify and assess optimum investments. People and the Environment: A Focus of Cooperation Engaging stakeholders in issues that affect them. Beyond the obvious areas of economic cooperation in development of the river, there are many ways in which cooperation can improve the lives and livelihoods of the people of 66 THE NIGER RIVER BASIN: A VISION FOR SUSTAINABLE MANAGEMENT the Basin, as well as improve the environment, reversing degradation and enhancing sustainability. The river basin organization has an important role to play in promoting engagement of a wide range of stakeholders with diverse interests. A small and modestly funded organization is limited in what it can do in a basin with about 100 million people--people who speak diverse languages and who are spread across enormous distances. Nevertheless, in a spirit of cooperation and transparency, the NBA can set an example of leadership in a culture of openness, consulta- tion, involvement, and inclusion. This can be done through several media, through interviews in national languages in the domestic media of the member countries and through newsletters and the Web. The NBA, as part of its institutional renewal, intends to follow this path. Migration: a tradition as old as the river itself. The Niger Basin is at the center of an important migration flow from north to south, due to economic differ- ences and the demand for labor. The poorer and drier countries of Burkina Faso, Chad, Mali, and Niger export their labor to the coastal and wetter countries of Nigeria, Côte d'Ivoire, Benin, and Cameroon, largely for the production of cash crops (including coffee, cocoa, and bananas). To a lesser extent, there is also the migration of the Bozo and Somono fishermen to the large reservoirs on the Niger River and of pastoralists, with their stock, to the Inland Delta in the dry season. Migration and large-scale demographic movements have in large part developed in response to the river and the seasons, with herders moving their cattle and sedentary farmers relying on the bounty of the Inland Delta and flow-recession agriculture to raise their crops. Consequently, migration is long established and accepted in the region and is an efficient means of ensuring the effective, sustainable, and efficient use of natural resources. With population growth that averages 3 percent in the Niger Basin, pressure on existing resources has increased dramatically, in places leading to resource conflicts. War and conflict add stress. During recent decades, civil war and unrest in several countries that border the Niger Basin have made it the recipient of large numbers of people displaced by violent conflict, adding pressures and stresses to already fragile lands. For example, in 2003 more than 25,000 refugees settled in the Fouta Djallon and Mount Nimba regions of Guinea. This led to increased degradation of the highlands, with rapid deforesta- tion and associated land degradation, soil erosion, gullying, and loss of productive lands. Loss of absorption capacity causes rapid runoff, with the consequences downstream of high sedimentation, siltation of existing infrastructure, floods, and changes in river flows. Root causes of environmental degradation. Major environmental degradation in the Niger Basin results from either natural or anthropogenic causes. COOPERATIVE DEVELOPMENT OF THE NIGER RIVER BASIN 67 Natural causes relate to climatic variability and change, in particular the decrease in rainfall in the Basin since the late 1970s. The major anthro- pogenic causes are land degradation, deforestation, and soil erosion that have taken place in the watershed in large part because of increased demographic pressure. Four principal environmental issues. Four principal environmental issues-- land degradation, water degradation, deforestation, and biodiversity loss--have a synergistic effect on water resources in the Basin. Land degradation in the form of erosion results from inappropriate agriculture practices, such as bush fires, clearance for rice paddies, extensive cultiva- tion, overgrazing, and reduction of wetlands from drainage. Water degradation, mainly the deterioration of water quality, results from non-point-source impacts from pesticides and fertilizers used in agricul- ture, from point-source urban pollution, and from lack of sanitation infrastructure (sewerage). Deforestation is the result of increased needs for energy and limited access to electricity; people in the Basin use wood and charcoal for domestic purposes (which also contributes to land degrada- tion). Biodiversity loss is caused by habitat destruction and a subsequent increase of invasive species, which are in turn caused by inappropriate fishing practices, deforestation, and land conversion for agriculture. Potential roles of the NBA. Each of these issues is extremely important. However, it is also important that the member countries and donor organi- zations not burden the NBA with a mandate and expectations of deliver- ing projects and action on the ground in all areas. Nevertheless, whereas resolution of many of these issues clearly lies beyond the capacity of the NBA, the institution can play an important role in increasing awareness of transboundary impacts of socioeconomic pressures on natural resources. In addition, the NBA can assist member countries in identifying invest- ment resources to protect the Basin and its watershed, thereby providing benefits, not only to the country where the protection is undertaken, but also to the downstream countries, which will benefit from the protection of the source through improved water quality, controlled runoff, and reduced sedimentation. In some cases, the downstream benefits from watershed rehabilitation and protection investments upstream might be so significant that downstream countries receiving this benefit will invest jointly in such activities. The subsidiarity principle will help the NBA to identify areas, as part of the SDAP, where the institution will have a comparative advantage over well-established national and local agencies that are also charged with working on these matters.10 The key question to ask is whether action in this field is part of the core NBA mandate and whether a transnational approach by the river basin organization is the most appropriate way to tackle a particular issue. 68 THE NIGER RIVER BASIN: A VISION FOR SUSTAINABLE MANAGEMENT Criteria for Success and Ways Forward There is significant regional development and integration potential among and between the Niger Basin countries, potential that could provide con- siderable development benefits for all involved. Enhanced cooperation on the management and development of the resources of the river can help to real- ize this potential, whereas unilateral actions will not. The commitment of the Niger Basin countries to the Shared Vision shows clearly that, at the level of the heads of state, the choice in favor of cooperation has been made. The path ahead is clearly difficult, but, as noted by Nigerian President Olusegun Obasanjo at the Niger Basin Heads of State Summit in January 2004, "The Shared Vision constitutes the ideal, if not the sole, way to follow, so as to preserve the environment and enable joint development of the Niger Basin" (Resolution of the January 2004 Heads of State Summit). It is now up to the NBA and its stakeholders, which include the international donor commu- nity, to make this vision a reality. As the countries move forward, the fol- lowing elements can be summarized as key ingredients for success: · Continued strong political leadership and commitment to the Shared Vision are required to ensure that the process moves forward and that it pro- duces tangible results. · Staying the course of the reform process. The NBAis currently going through a major reform process, which will involve several difficult decisions. However, it is important that the member stakeholders stay the course of reform, so that the institution can regain its relevance and legitimacy, and establish a strong national constituency. · Leadership and champions. Moving a complex, nine-country water man- agement and development agenda forward will take a sophisticated, open, dynamic institution with an inspired leadership, as well as national champions, who clearly see the importance of "hydropolitical" engage- ment, and who will drive the Niger River Basin development agenda so that the benefits of cooperative investments can be realized, contributing to the poverty-reduction priorities of the member countries. · A dynamic and enabled staff . . . Continued and strong leadership will be pro- vided by the Heads of State Summit. The Council of Ministers, supported by the Technical Committee, will continue to give direction and guid- ance. However, the day-to-day task of delivering on the Shared Vision for the member stakeholders will be that of the staff of the NBA. It is therefore extremely important that the current reform process take root and that the staff be technically skilled and competent, motivated, and empowered to undertake this vital task. Reform holds the promise of delivering this key ingredient for success. · . . . in a financially viable institution . . . The commitment made at the polit- ical level is historic and holds great promise. The instructions given to COOPERATIVE DEVELOPMENT OF THE NIGER RIVER BASIN 69 the NBA are clear and resounding. Yet, the objectives can be met only if the countries ensure that their financial commitments are kept, allow- ing the NBAto remain financially sustainable and autonomous, to attract highly skilled staff, and to continue to work on its core mandate of river basin management and development. · . . . that continues to stay on message. Having a reliable resource flow from the member countries will allow the institution to stay on message and on mandate, because it will not have to pursue marginally relevant projects to ensure institutional survival. Moving beyond unilateral planning . . . It has been argued in this chapter that cooperative planning and development are the only viable way forward for the Niger Basin countries. The Niger Basin heads of state have made clear commitments to a cooperative path and have instructed the NBAto organize itself accordingly. To manifest commitment to the cooper- ative agenda, it is important that each of the countries review its national water resources management plans to assess whether viable alternatives might exist if development is now viewed through the lens of the broader, regional river basin. . . . facilitated by the "hydro-diplomacy" of the renewed NBA. The difficult task of assessing and comparing optimum investments in the Basin, which will yield the greatest number of benefits to the largest number of members, in a context of social and environmental stewardship, is by no means simple. Yet, it is exactly this task that is now required of the renewed NBA if real and tangible development benefits are to be realized for the people of the Niger River Basin. Development partners commit to their side of the compact. Several donors, including the World Bank, have committed to supporting the member states and the NBA as they embark on reforming the institution and together defining their Shared Vision and SDAP. It is important that the donor community now put aside any individual preferences for national investments, in an effort to let optimal regional solutions emerge through the Shared Vision process. It is equally important that donor partners continue to support the Niger Basin countries and the NBA strongly, as they embark on this historic process that holds the promise of unleashing the development potential of the river for all the people of the nine Basin countries. Appendixes Appendix 1: Main Maps of the Niger River Basin Map 1: Niger River Basin Map 2: The Upper Basin of the Niger River and the Bani River Map 3: Inland Delta and Lakes District Map 4: Middle Niger (Northern Section) Map 5: Middle Niger (Southern Section) Map 6: The Benue River Map 7: The Lower Niger River and the Niger Delta Map 8: Geographical Features Map 9: Niger Basin (Lapie, 1829) Map 10: Navigable Segments of the Niger River Map 11: Rainfall Patterns Map 12: Representative Annual Rainfall Distribution Map 13: Estimated Average Flows and Evaporation Rates on the Niger River Map 14: HYDRONIGER Data Collection Stations along the Niger River and Its Major Tributaries Map 15: Interior Delta of the Niger River 70 APPENDIXES 71 IBRD 33853 ° ° ° 20 Bank. 15 10 °5 Bank any World or information The World of other The territory, Unit any CHAD of any CENTRAL AFRICAN REPUBLIC and part of Design the N'DJAMENA eoKbi on status boundaries. ° Map such ayM 15 the legal yeR of imply, the oya by denominations AFRICA Maroua not on Lake Chad M ° do aruoL 15 colors, acceptance oyaM Map produced map judgment or le of was this iT oyaM Garoua on any Area map boundaries, Faro This The shown Group, endorsement Maiduguri olaY AOUNDÉY alognoG CAMEROON iloG Bamenda Wale ° 10 Ala ° 10 NIGER Douala Zinder S hemank ar Katsina Ala Kano . R Agadez NIGERIA ara m Benue Katsina Makurdi Maradi Gadaandawad Jibiya usU MALABO a TORIAL abaknib luoG an rbm anA Onitsha t GUINEA Goulbins ABUJA araruG regiN akraT Chiwa w Kaduna .R ninoK udaK EQUA a emE okabG Lokoja Kampe Harcourt amiR amfraZ a Por Sokoto Ka rnogataK ukE Jebba °5 ma voir Kainji °5 ahouaT Jebba Reser ih Ibadan iruuaM lollaD iR-otokoS voir SwSwa Lagos ALGERIA assoB lollaD Niger R. Kainji Reser atoS TO- Malanville irobil A N I N E B POR NOVO NIAMEY uorkeM riréjdÉ aopaT irajdneP O G O T Kandadji LOMÉ Fafa ismeliT ud e éllaV Ansongo ibruoG Gao iO t °0 ossayeT uoloroG Dargol abriS ACCRA Guinea °0 Lake oltaV of .RregiN ASOF Sekondi- akoradiT youmé Ouahigouya MALI BURKINA GHANA Gulf Kor Kumasi Dire ° mbuktuiT Macina Ké 20 Mopti OUAGADOUGOU Bobo Dioulasso °5 inaB Abidjan Banifing San Bouaké °5 D'IVOIRE Markala AMOUSSOUKROY BOUNDARIES BOUNDARIES LIMITS CITIES CAPITALS éogaB Sikasso Korhogo Daloa BASIN ROADS Néma Ségou CÔTE RIVER HYDROGRAPHIC MAIN SELECTED NATIONAL INTERNATIONAL .RregiN Koulikoro éluoaB 'Atroûs BASIN ANIA el inaraknaS noiD yoûn Sahel eiF 'A Nioro du BAMAKO Mil o ° Kita Siguiri 10 eluoaB RIVER ossikniT .R Kankan nadnaiN Kissidougou ° 10 MAURIT regiN u ofaM Greenville LIBERIA STATIONS Faranah SITES Kayes Miles Kilometers fa 200 NIGER Kif Dabola 300 Bo RIVERS RIVERS MONITORING SIERRA LEONE MONROVIA 200 1 PERENNIAL TEMPORARY LAKES/RESERVOIRS SELECTED CITIES/MONITORING Labé 100 Aleg mbacoundaaT GUINEA Y 100 ° 15 ° ° 15 SENEGAL 10 FREETOWN °5 0 0 CONAKR JULY 2005 Map 72 THE NIGER RIVER BASIN: A VISION FOR SUSTAINABLE MANAGEMENT IBRD 33934 ° ° ° ° 14 13 12 11 °9 OF AND °4 Mopti u a e °4 BASIN RIVER LA BOUNDARIES t BASIN RAPIDS RIVERS °4 CAPIT é a RIVER CITIES l DAMS P Bobo Dioulasso TIONAL Inland Delta Djenn a r ASOF RIVER AND ROADS BANI TIONAL a ALLSF EXISTING PERENNIAL MAIN SELECTED NA INTERNA San g NIGER °5 a BURKINA UPPER inaB i NIGER d THE n a °5 B THE THE °5 ° 10 °9 Kirango MacinaéK Markala 100 Banifing Koutiala °6 Douna gouéS Korhogo 75 50 °6 Dam Sikasso KILOMETERS Bago é 25 Markala BANI Boundaili TERSHED D'IVOIRE 0 °7 W MALI TE Bank. °7 Bank any .R regiN A Ô World or information The World Rapids Rapids él C of other The territory, Unit any of uoaB any Kenie Odienne Sotuba and part of °8 Design the é on status boundaries. voir Map such Koulikoro the legal of imply, linguéS Reser by denominations the not on é do colors, acceptance produced map judgment or linguéS Dam was this on any map boundaries, BAMAKO °9 ° ° eiF inaraknaS noi D This The shown Group, endorsement 14 13 NIGER o Sahel ° ° 15 10 . °9 REP Nio du CHAD Kankan BASIN TERSHED ° CENTRAL AFRICAN ° oliM AFRICA 15 Lake Chad Kita A 15 Siguiri .R of see Niger River Basin 33938 regiN River detail, nadnaiN ° R CAMEROON For IBRD ° ° UPPER nadnaiN W Niger ° 20 10 Baro Headwaters the 10 see eun 10 ° NIGER 33937 Be detail, NIGERIA ossikniT 10 Kissidougou For IBRD GUINEA EQ. Kouroussa uofaM °5 see GUINEA ALGERIA see R. Faranah NINEB 33939 33936 detail, detail, Niger OGOT Tonboli °0 IBRD For IBRD For °0 élaB ° Kayes 11 MALI ASOF Dabola BURKINA GHANA see Guinea °5 33935 of detail, °5 For IBRD .R TEÔC regiN D'IVOIRE Gulf jallonD ° 12 Massif SIERRA LEONE ° ANIA ° 10 Map ° of Fouta 12 10 2 LIBERIA MAURIT Area GUINEA SIERRA LEONE é ° ° ° ° ° Lab ° ° 15 20 15 SENEGAL 10 °5 12 11 10 °9 MAY 2005 Map APPENDIXES 73 IBRD 33935 ° ° ° ° ° 17 16 15 15 10 . REP CHAD ° CENTRAL AFRICAN ° 15 AFRICA 15 Lake Chad see Niger River Basin 33938 detail, ° R CAMEROON For IBRD ° ° 20 10 see eun 10 NIGER 33937 Be detail, NIGERIA For IBRD GUINEA °2 EQ. .RregiN °2 °5 MALI see ALGERIA see NINEB 33939 33936 Niger R. OGOT detail, detail, °0 IBRD For IBRD For °0 OS Ouahigouya Delta Do FA MALI BURKINA GHANA Lake Map Guinea °5 of of é Area .R TEÔC °5 Lower youm °3 regiN D'IVOIRE Gulf see Kor Niangay °3 ° ANIA 10 33934 ° detail, LIBERIA 10 Lake MAURIT For IBRD mbuktuiT GUINEA SIERRA LEONE ° ° ° ° 15 20 15 SENEGAL 10 °5 é ° ° Dir 14 13 Goundam leeT °4 Lake é grEéknuofaiN Korientze Lake Korientze Kona u a e OS t a FA °4 Aka Mopti l P BURKINA Niafounk Faguibine .R a r a Lake Debo g Inland Delta regiN a Kouakourou i Lake d n a B District akaiD Djenne San on Lakes by The the Delta of and shown Bank on °5 imply, territory, or Unit boundaries, produced not World The do of of was Design information The Bank. denominations map of dgmentujyna any such Markala Dam endorsement map Map other this part This the World colors, any on the Group, statuslagel any or acceptance boundaries. Central inaB MacinaéK °6 AND °6 Delta Douna BASIN AT BOUNDARIES ANIA Markala °6 75 RIVERS DISTRICT DAMS CITIES gouéS TIONAL Upper RIVER DEL ROADS 50 EXISTING PERENNIAL MAIN SELECTED INTERNA MAURIT NIGER 25 KILOMETERS LAKES regi R. INLAND 3 0 °7 N maéN ° 16 °7 ° ° ° 15 14 13 MAY 2005 Map 74 THE NIGER RIVER BASIN: A VISION FOR SUSTAINABLE MANAGEMENT 18° 1° 0° 1° 15° 10° 5° 0° 5° 10° A L G E R I A AFRICA 20° Niger Vallé River M A U R I TA N I A 20° Basin For detail, see M A L I N I G E R 15° 15° For detail, see 15° 17° Bourem Niger R. eduTilemsi IBRD 33935 Area of Map For detail, see IBRD 33934 17° SENEGAL Lake Chad Tossaye NigerR. BURKINA NigerR. IBRD 33937 CHAD FASO GUINEA N I G E R I A 10° 10° Gao SIERRA LEONE GHANA Be n ue R CÔTE LIBERIA TOGO D'IVOIRE BENIN 16° 16° CENTRAL AFRICAN M A L I 5° CAMEROON For detail, see REP. Ansongo G u l f o f G u i n e a IBRD 33939 For detail, see 10° 5° 0° EQ. GUINEA 10° IBRD 33938 15° Fafa 2° Koryoumé3 ° 4° This map was produced by 5° Labézanga the Map Design Unit of The World Bank. The boundaries, 15° colors, denominations and 15° any other information shown on this map do not imply, on Gorouol Kandadji the part of The World Bank Group, any judgment on the legal status of any territory, or any endorsement or acceptance of such boundaries. Dargol Tillabéri 14° Dargol N I G E R 14° NIAMEY ya DallolBosso B U R K I N A Sokoto 13° Maouri FA S O 13° Sirba Goroubi Diamangou Kirtachi Foga olll Dallol Gambou Da Boumba OUAGADOUGOU Sokoto-Rima Tapoa Mekrou Djongdjonga Zamfara 12° 12° Malanville Ka Alibori NigerR. N I G E R I A Pendjari 11° Mekrou Kandi Sota 11° G H A N A Malendo 0° Kainji NIGER RIVER BASIN Reservoir Katagonra MIDDLE NIGER 10°(Northern Section) 10° B E N I N 10° PLANNED DAMS T O G O Oli Eku EXISTING DAMS PERENNIAL RIVERS Parkou MAIN ROADS AUGUST 9° SELECTED CITIES 9° 0 25 50 75 100 9° IBRD NATIONAL CAPITALS KILOMETERS 2005 33936 INTERNATIONAL BOUNDARIES 1° 0° 1° 2° 3° 4° 5° Map 4 APPENDIXES 75 IBRD 33937 ° ° ° ° °9 °8 15 10 . 11 10 REP CHAD ° CENTRAL AFRICAN ° 15 AFRICA 15 Lake Chad see ° ° ° 11 11 Niger River Basin 33938 11 Bank. detail, Bank any BASIN LSA BOUNDARIES NIGER or ° R CAMEROON For IBRD ° World RIVERS CAPIT ° 20 information Goli DAMS DAMS CITIES TIONAL 10 Map eun 10 The World of Section)n other The territory, ROADS NIGER of Be RIVER Unit any of any TIONAL NIGERIA GUINEA and part of PLANNED EXISTING PERENNIAL MAIN SELECTED NA INTERNA Area Design the boundaries. EQ. ° °5 MIDDLE on status ° Map ° such NIGER Wale 10 see 10 10 the legal of imply, (Souther ALGERIA see R. by denominations the NINEB 33939 not on 33936 Niger detail, do detail, OGOT colors, °0 For IBRD acceptance produced map alognoG For IBRD °0 judgment or was this any MALI ASOF on map boundaries, BURKINA GHANA This The shown Group, endorsement see Guinea Shemankar °5 °9 Zinder 33935 of Jos detail, °5 °9 Plateau For IBRD .R TEÔC regiN D'IVOIRE Gulf Kano ° ANIA see 10 Makurdi 33934 ° 10 NIGERIA detail, LIBERIA MAURIT For IBRD GUINEA SIERRA LEONE Kaduna ° ° ° ° °8 °8 15 20 15 SENEGAL 10 °5 ° ° ° 14 13 12 ABUJA aramusU BenueR. Maradi °7 Kaduna °7 bniluoG s Gada Chiwandawad araruG Gusau Lokoja Sokoto anudaK Lokoja okaB °6 agiraM °6 a amiR odnel Kontagora Sokoto arafmaZ bakoS Ka M a °5 lwaeY voir ar ogatn oK orO °5 nihsO Kainji Reser nuwA °4 iruoaM amiR-otokoS Jebba Oli ihcsoM °4 lollaD uodohC 100 onoN 75 50 Sota KILOMETERS ossoB 25 °3 lollaD Niger R. 0 °3 irobilA uorkeM BENIN 5 ° NIAMEY ° ° ° ° 14 13 12 11 10 °9 °8 JULY 2005 Map 76 THE NIGER RIVER BASIN: A VISION FOR SUSTAINABLE MANAGEMENT IBRD 33938 ° ° 11 10 °9 °8 ° ° ° 15 10 . 16 REP CHAD ° ° CENTRAL AFRICAN ° 15 16 AFRICA 15 Lake Chad Map CHAD Kabia Niger River Basin of ° R CAMEROON ° ° 20 10 see eun Area 10 ° NIGER 15 33937 Be ° detail, NIGERIA 15 yeR For IBRD GUINEA EQ. ibeK °5 see NINEB 33939 Maroua oyaM Mayo ALGERIA see 33936 Niger R. OGOT detail, detail, ° Dam °0 IBRD 14 For IBRD For °0 ° OS 14 .stM aradnaM Lagdo chollireT idoG FA MALI BURKINA GHANA see Guinea voir °5 33935 Lagdo detail, Garoua Reser For IBRD .R TEÔC of °5 CAMEROON D'IVOIRE Gulf ° ° Faro NIA regiN 13 Far o 13 ° A see 10 33934 ° detail, LIBERIA 10 la waH olaY Mts. u IBRD a MAURIT For et GUINEA SIERRA LEONE Ini Alantika a lP ° ° ° ° 15 20 15 SENEGAL 10 °5 a w ° Biu Belwa stM a m °6 on 12 Plateau .R euneB ihsbehS a d by The the A of and shown Bank on imply, territory, or Unit boundaries, produced not World The do judgment anyfo such of was Design information The m Mts Bank. denominations map of any endorsement map Map other sutats part Ka this any This the World colors, any on the Group, legal or acceptance boundaries. ° Gotel m) 11 ija Oku alognoG an iloG Taraba B Pic (3008 Donga ° Wabe Massif 10 10 Metchum ° Bamenda Shemanker Bamenda nAkur Katsina Ala °9 °9 NIGERIA Jos Plateau Makurdi adaM °8 nueR. °8 ABUJA awkO eB 100 BASIN RIVER AL BOUNDARIES 75 RIVERS °7 DAM CITIES CAPIT TIONAL 50 °7 RIVER ROADS TIONAL BENUE R. .R regiN 25 KILOMETERS EXISTING PERENNIAL MAIN SELECTED NA INTERNA 6 NIGER anudaK THE Niger 0 Lokoja ° ° °6 11 10 °9 °8 °7 °6 °5 °6 JULY 2005 Map APPENDIXES 77 5° 6° 15° 10° 5° 0° 5° 10° A L G E R I A AFRICA 20° Niger River M A U R I TA N I A 20° Basin For detail, see M A L I IBRD 33935 For detail, see For detail, see IBRD 33936 IBRD 33934 N I G E R 15° 15° For detail, see 15° SENEGAL IBRD 33937 Lake ABUJAR. Chad BURKINA 9° 9° Niger NigerR. CHAD FASO GUINEA N I G E R I A NigerR. 10° 10° SIERRA R LEONE GHANA Be n ue CÔTE LIBERIA TOGO D'IVOIRE BENIN CENTRAL AFRICAN 5° Area of CAMEROON REP. Map G u l f o f G u i n e a For detail, see IBRD 33938 10° 5° 0° EQ. GUINEA 10° 15° 7° 8° NIGER RIVER BASIN 9° 8° 8° 8° R. Lokoja Benue THE LOWERMakurdi NIGER RIVER Lokoja AND THE NIGER DELTA PLANNED DAMS PERENNIAL RIVERS MAIN ROADS SELECTED CITIES INTERNATIONAL BOUNDARIES 7 ° 8° 9° N I G E R I A Anambra Enygu Onitsha Onitsha 6 ° 6 ° R. ger Ni 5 ° 5 ° Nu Port Harcourt n This map was produced by the Map Design Unit of The World Bank. The boundaries, colors, denominations and N any other information shown on this map do not imply, on i the part of The World Bank ge 0 25 50 75 MA Group, any judgment on the IBRD legal status of any territory, r Y or any endorsement or D e l t a KILOMETERS 2005 acceptance of such 33939 boundaries. 6° 7° 8° 9° Map 7 78 THE NIGER RIVER BASIN: A VISION FOR SUSTAINABLE MANAGEMENT IBRD 33870 ° ° 15 10 °5 Bank. Bank any World or information The World of other The territory, Unit any of any CHAD CENTRAL AFRICAN REPUBLIC and part of N'DJAMENA ° Design the on status boundaries. 15 Map such the legal of imply, by denominations the AFRICA not on Lake Chad Maroua do colors, acceptance Map produced map judgment or of was this on any Garoua É Area map boundaries, Faro This The shown Group, endorsement 12 Maiduguri 4 olaY OUNDAY ° 20 CAMEROON anudaK al ognoG 3 Bamenda ° Wale 10 ° 10 Ala NIGER Shemank ar Kat sina Douala Zinder 5 .R Kano Agadez NIGERIA ABUJAara Benue Makurdi MALABO musU 4 Maradi TORIAL a an 2 GUINEA Gad ndawad araruG t Chiwa .R regiOnitshaN 1 ninoK Kaduna udaK EQUA Lokoja a emE okabG Harcourt amiR amfraZ a a K n Wa Ku i rnogataK Por ukE °5 ma Sokoto ibuG voir °5 6 houaaT 6 iR-otokoS Jebba Reser ih a Ibadan Sw 9 ALGERIA Lagos atoS TO- NIAMEY POR NOVO Malanville irobil A N I N E B uorkeM É illaberiT 3 Niger R. O G O T LOM °0 Ansonso Gao uoloroG ACCRA Guinea °0 9 Lake oltaV ssayoT of MALI .RregiN 7 ASOF Sekondi- koradiaT Ouahigouya BURKINA GHANA Kumasi Gulf ° mbuktuiT 8 Mopti OUAGADOUGOU 20 Bobo Dioulasso é °5 inaB Abidjan 11 Bouak 7 °5 D'IVOIRE Markala AMOUSSOUKROY Sikasso Korhogo BOUNDARIES BASIN maéN gouéS éogaB TE Daloa Ô CITIES CAPITALS Koulikoro RIVER .RregiN éluoaB 9 C RIVERS NIGER SELECTED NATIONAL INTERNATIONAL sû 'Atro BASIN FEATURES elnû in ANIA araknaS 10 noiD Sahel eiF yo Nioro du BAMAKO Mil o ° 'A Kita Siguiri eluo aB 10 RIVER ossikniT nadn Greenville DELTA) Kouroussa .RregiN Kankan aiN ° Kissidougou 10 u ofaM NIGER MAURIT LIBERIA Kayes Miles Kilometers (NIGER af 200 300 VALLEYS Kif Dabola (GUINEA) (PLATEAU) Bo GEOGRAPHICAL REGION WADIS (ADAMAWA) & LUMES BASIN PLAINS PLAINS PLATEAU SIERRA LEONE MONROVIA 200 PLATEAU é COASTAL LOW NIGER-BENUE HIGH JOS DALLOLS TIMBUKTU SEGOU HIGH HIGHLANDS SANDSTONE HIGHLANDS 8 Lab 100 Aleg ambacoundaT GUINEA Y 100 ° 1 2 3 4 5 6 7 8 9 10 11 12 15 ° ° 15 SENEGAL 10 FREETOWN °5 0 0 CONAKR AUGUST 2005 Map APPENDIXES 79 9 Map 80 THE NIGER RIVER BASIN: A VISION FOR SUSTAINABLE MANAGEMENT IBRD 34004 ° ° ° 15 10 °5 20 Bank. Bank any World or information The World of other The territory, Unit any of any CHAD CENTRAL AFRICAN REPUBLIC and part of N'DJAMENA Design the boundaries. ebi ° eoKb 15 on status Map such ayM yeR the legal of imply, oya by denominations the ° AFRICA not on Lake Chad aru Maroua M 15 do oL o colors, acceptance yaM Map produced map judgment or of was this leiT oyaM Garoua on any É Area map boundaries, This Fa ro The shown Group, endorsement a Maiduguri olaY AOUNDY CAMEROON ahudaK al ognoG 3 Bamenda ° Wale 10 ° 10 NIGER Shemank aarr i Katsiana Ala Douala Zinder Ala Kano . R Agadez NIGERIA arra MALABO m Benue Katsina usU Makurdi 2 b Maradi a TORIAL abaknib luoG an br ABUJA m an A Onitsha t GUINEA n Goulbins Gaaddaa ndawad Jibiya aararuG regiN 1 akraT Chhiiw .R ninoK Kaduna udaK a pe 5 Lokoja EQUA a emE okabG Kam Harcourt g amiR Por Sokoto i kE Jebba °5 amfraaZ aK aKa n ubiG rnogataK u °5 ma 8 voir houaaT m 8 Jebba Reser ih 1 1 iruuaM l iR-otokoS - Kaniji oollaD Swa Ibadan ALGERIA assoaB Lagos lollaD Niger Rr. O-T l 5 a attooS Malanville irobil A N I N E B POR NOVO NIAMEY uorkeM É riréjdÉ aopaT e irajdneP ok O G O T LOM Kandadji Fafa ismelliT ud l e é a 7 ibruoG °0 llaV Ansongo b iOt Gao ossayeT 6 uoloroG Dargol abriS i ACCRA °0 Guinea Lake oltaV of BOUNDARIES 1 LIMITS .Rre é ASOF Sekondi- akoradiT CITIES CAPITALS r ggiN youm MALI Ouahigouya BURKINA GHANA Gulf BASIN ROADS Kor Kumasi Dire RIVER RIVER MAIN SELECTED NATIONAL INTERNATIONAL ° 20 mbuktuiT MacinaéK 6 Mopti OUAGADOUGOU Bobo Dioulasso é NIGER °5 inaB Abidjan Banifing San Bouak °5 STATIONS THE Markala D'IVOIRE SITES gouéS MOUSSOUKROAY Sikasso Korhogo BASIN OF RIVERS RIVERS maéN 4 éogaB TE Daloa Ô MONITORING RIVER .RregiN C Koulikoro éluooaB sû PERENNIAL TEMPORARY LAKES/RESERVOIRS SELECTED CITIES/MONITORING 'Atro NIGER ANIA elnû inaraknaS noiD yo Sahel eiF SEGMENTS ° 'A Nioro du Kita BAMAKO Mil o e 10 Siguiri luo aB ossikniTi 3 n nadn aiN ° Kissidougou 10 MAURIT .RregiN Kankan u ofaM Greenville LIBERIA Faranah Kayes Miles Kilometers af 200 NAVIGATION 300 June-December August-November August-January August-February September-December November-March Kif Dabola Bo NAVIGABLE MONROVIA é SIERRA LEONE 200 PERMANENT SEASONAL SEASONAL SEASONAL SEASONAL SEASONAL SEASONAL NON-NAVIGABLE 10 Lab 100 Aleg mbacoundaaT GUINEA Y 100 ° 1 2 3 4 5 6 7 8 15 ° ° 15 SENEGAL 10 FREETOWN °5 0 0 CONAKR AUGUST 2005 Map APPENDIXES 81 IBRD 33871 ° ° 15 10 °5 Bank. Bank any World or information The World of other The territory, mm Unit any of any CHAD mm CENTRAL AFRICAN REPUBLIC and part of N'DJAMENA Design the mm ° boundaries. 009 1100 15 on status Map such the legal 1300 of imply, by denominations the AFRICA not on Lake Chad Maroua do colors, acceptance Map produced map judgment or of was this Garoua on any É Area map boundaries, This Faro The shown Group, Maiduguri endorsement mm 400 mm mm AOUNDY 500 700 olaY mm ° 20 0mm 1500 50mm 100mm 200mm 30 CAMEROON al og 2000 mm anudaK noG Bamenda 2500 mm ° Wale 3000 mm 10 ° NIGER 10 Ala Shemank ar Kat sina Douala Zinder .R Kano Agadez NIGERIA ABUJA a ra Benue t Makurdi MALABO musU Harcourt Maradi TORIAL a Onitsha GUINEA Gad ndawad an Por araruG Chiwa .R regiN ninoK Kaduna udaK EQUA a emE okabG Lokoja amiR Sokoto i °5 amfraaZ aK Ku n ubi rnogataK ukE Wa G voir mm °5 ahouaT otokoS Jebba Reser 4000 ih a ALGERIA Ibadan Sw 50mm Lagos atoS TO- NIAMEY POR NOVO Malanville irobil A N I N E B uorkeM É illaberiT er R. O G O T LOM Nig °0 Gao ACCRA °0 ouoroG l Guinea Ansonso Lake oltaV ossayT of .RregiN ASOF Sekondi- akoradiT MALI Ouahigouya BURKINA GHANA Kumasi Gulf 100mm mbuktuiT Mopti OUAGADOUGOU °5 é 200mm Bobo Dioulasso Abidjan Bouak 300mm ina °5 Markala B D'IVOIRE AMOUSSOUKROY Sikasso maéN mm éogaB Korhogo 400 mm gouéS Daloa 500 .RregiN TE Koulikoro éluoaB 1500 1800 m mmm Ô C ° 20 sû Was oulou s ANIA 'Atro elnû mm in araknaS noiD Sahel yo Nioro du 700 mm eiF BAMAKO Mil o ° 'A 900 Kita Siguiri e 10 luo aB MAURIT mm ossikniT nadn aiN ° Kissidougou 10 Greenville BASIN BOUNDARIES 1100 Kouroussa u ofaM mm .RregiN Kankan LIBERIA Miles BASIN Kayes PATTERNS Kilometers (Annual millimeters) CITIES CAPITALS 1300 fa in RIVER RIVER Kif mm Dabola RIVER mm 2200mm 200 300 ISOHYETS rainfall NIGER NIGER SELECTED NATIONAL INTERNATIONAL 1500 1800 SIERRA LEONE MONROVIA 200 100 NIGER 11 RAINFALL Aleg mbacoundaaT Y 100 ° 15 200mm GUINEA ° ° 15 SENEGAL 10 FREETOWN °5 0 0 CONAKR AUGUST 2005 Map 82 THE NIGER RIVER BASIN: A VISION FOR SUSTAINABLE MANAGEMENT IBRD 34132 N° °0 15 Logone mm N°5 not Bank. do Bank such CENTRAL E°5 AFRICAN REPUBLIC the rldo map rldo legal of CHAD Djamena' 1100 CONGO by W W the other any N this The any The on or,y of on colors, oft F M A acceptance J M Lake F M A M é produced and J D J F M A Chad J J Unit par shown judgment territor or N M M A O SA J J D J F M D J N S A F M A M batiiT J J was the N J O S A mm O J J D any any D J N O S A aganaS O S aoundY map Design boundaries, ationm on, of olaY N A Bilma 500 mm CAMEROON F M A M J This Map The denominations J infor imply Group, status endorsement 1500 mmmm Nguigmi D J Maiduguri N O S A GABON E°0 110000 F M A Zinder Jos euneB J M J F M A E1°0 D J J M J N D J O S A N Nkongsamba O S A NIGER Makurdi F M A A J M F M J J M J M A D J F M A M D J F J M J Agadez N O S A J J N A D J Douala F M A J O S A J M D N J Kano N O S A O S D J NIGERIA Enugu Libreville N Abuja O S A F M A J M J Malaba émoT D J F M A N O S A J M J F M A J M D J J A t oãS D J regiN N O S ahouaT Minna N GUINEA O S A E1°5 F M A J M J D J Harcourt N O S A Ilorin Por F M A ORIALT J M NCIPEÍ E1°5 J D J N PR Lake O S A Kainji ALGERIA Novot EQUA Benin DISTRIBUTION Niamey F M A AND J M J Kandi Por D J of É M F M A F M A N F A M J M A M Kidal J J O S J D J -é é J J J D J D N A N A é F M A S O S A S O TOM J M N J BENIN Sav O ALL D J Sokode Bight N Lom O S A Niger M A F M A F J °0 Gao Sansann Mango J M J T O G O J M D J D J OÃS N M A N S A F M A F A A Guinea M M S A F M O J M M F M O J J J J J J J D J D J D J D J BASIN N A A N A N A Accra N O S O S O S O S ASOF é F M A RAINF of J M J °0 D J Dori F M A KILOMETERS Ouagadougou White J M J Lake oltaV N O S A D J Kpalim RIVER MALI N A F M A J M Volta O S 750 J koradiaT D J F M A J M J F M A M N J Gulf O S A amaleT GHANA D J J N J O S A D N M A F M A F O S A M J M J J J BURKINA Gaoua Kumasi D J D J Black Volta N A N O S NIGER O S A F M A ANNUAL J M J Mopti D J N Axim A O S A W°5 F M 500 J M é J Bobo- M A M A D J F M F J J Komoe M J ombouctouT N Dioulasso J O S A D J D J TIVEA N O S A A F M A J M J mmmm D J dougoué IVOIRE'D Bouak N O S A F M J M J D J amoussoukroY Abidjan A N W°5 O 00 maéN inaB S A N O S TE Bandama F M A é Ferkess J M J 1001 F M A ÔC D J 250 N O S A J M regiN J mm uob D J N Ta O S A mmmm Bamako Odienn F M A M 1500 Sassandra F M A J J A M M A F M M 500 J J D J F M J Gagnoa J J D J N O S A J D J D J N O S A N O S A Man N O S A REPRESENT W° ANIA Nioro 0 10 F M A J M M A A J F J M M J F M A F M D J D J J M J J J N D J O S A N O S A D J djikjaiT af N O S A Greenville N O S A Kif Harbel Macenta F M A W° F M A M J M J F M A F LIBERIA M Kankan J J 10 D J D J J M J A M N A N D J J J mmmm O S O S A N O S A D J Bo N Kayes O S A F M A J M J F M A COURSES D J J M J MAURIT 1100 J DISTRIBUTION Kabala N D O S A N mm O S A COURSES Senegal bia GUINEA Monrovia ALL TERA ALS BOUNDARIES 1976. Gam 1500 mm.) TERA W LIMITS W° W CAPIT 15 LEONE (in RAINF y SIERRA Y TIONAL BASIN oupet,T Freetown TIONAL SENEGAL Bissau Conakr ISOHYETS MONTHL PERENNIAL INTERMITTENT NIGER NA INTERNA Source: W° 15 F 12 M A J M J Banjul D J Nouakchott N° N° THE GUINEA- BISSAU N° TLANTICA N OCEAN O SA 20 15 Dakar GAMBIA 10 °0 AUGUST 2005 Map APPENDIXES 83 IBRD 34133 N° N°5 °0 15 Logone not Bank. do Bank E°5 such CENTRAL AFRICAN REPUBLIC legal the CHAD orld map orld of CONGO by W W the other any this The any The on or,y of on colors, oft Djamena' Lake N 20 produced and acceptance Chad Unit par é shown judgment territor or was the any map Design boundaries, mation on, any of aganaS oundaY This Map The denominations infor imply Group, status endorsement boundaries. 87 E°0 CAMEROON GABON RIVER NIGER euneB 14 E1°0 93 NIGER NIGERIA 182 Libreville Malaba émoT Abuja 61 regiN oãS THE GUINEA E1°5 40 73 ON TORIAL NCIPEÍ E1°5 PR Kainji Lake TES ALGERIA 31 Novot EQUA Benin AND RA 27 Niamey Por of É é TOM -3 Niger BENIN Bight Lom TION °0 29 T O G O OÃS Guinea BASIN Accra of °0 White Lake oltaV KILOMETERS RIVER APORA MALI ASOF Ouagadougou Volta 750 EV BURKINA GHANA Gulf -25 Black Volta NIGER 55 14 AND W°5 Komoe 500 TE amoussoukroY Ô W°5 FLOWS regiN inaB 11 C IVOIRE' Bandama D 250 Sassandra 41 Bamako VERAGEA W° ANIA 0 10 7 29 W° TED LIBERIA 10 /year) COURSES 3 MAURIT l km COURSES Senega ESTIMA Gambia GUINEA SIERRA LEONE Monrovia TERA ALS BOUNDARIES /year) (in W 3 TERA W° km W CAPIT 15 TION y (in TIONAL LIMITS Nouakchott Freetown APORA TIONAL SENEGAL Bissau Conakr FLOWS EV PERENNIAL INTERMITTENT BASIN NA INTERNA W° 15 13 Banjul 29 -25 N° N° THE GUINEA- BISSAU N° TLANTICA OCEAN 20 15 Dakar GAMBIA 10 °0 AUGUST 2005 Map 84 THE NIGER RIVER BASIN: A VISION FOR SUSTAINABLE MANAGEMENT IBRD 34134 N° N°5 °0 15 Logone Bank. do rldo the any such CENTRAL E°5 AFRICAN REPUBLIC CHAD the rldo W map on of CONGO by W other The or,y this The any oft on Garoua of colors, par judgment territor Lake NíDjamena produced and acceptance Chad Unit the shown any any or of TRIBUTARIES was on, map Design boundaries, ationm Group, status imply aganaS YaoundÈ This Map The denominations infor not Bank legal endorsement boundaries. Lau E°0 CAMEROON GABON Gassol Tapare MAJOR NIGER euneB E1°0 Ibi ITS Ala Katsina- NIGERIA Abuja Makurdi Libreville Malaba TomÈ AND Baro rOnitsha egiN S,,o GUINEA Aval E1°5 Amont/ Wuya Lake Lokoja RIVER Kainji Kende dere-BodeiY Kainji Kainji E1°5 Jebba PRÕNCIPE Parc EQUATORIAL ALGERIA Barou Novo W. Benin AND NIGER Niamey Niamey Port of songo Niger Malanville THE BENIN Bight TOM... LomÈ °0 An Alcongui Kourou T O G O OS Campement Tossaye Kakassi Guinea BASIN Kandadji W. GarbÈ Accra °0 FASO of White Lake oltaV KILOMETERS RIVER ALONG MALI Ouagadougou Volta 750 yomÈ GHANA Gulf Kor DirÈ BURKINA Black Volta NIGER Mopti W°5 500 STATIONS Komoe Goundam Ke-macina Yamoussoukro Douna a W°5 regiN inaB C`TE Bandam DioÔla Pankourou DíIVOIRE 250 Kirango Sassandra Kenieroba SÈlinguÈ Banankoro Amont/Aval Samatiguila COLLECTION W° Koulikoro STATIONS 0 10 Bamako Kankan Baro DATA nkissoiT Faranah Kerouane W° LIBERIA COLLECTION 10 Kouroussa DATA COURSES MAURITANIA GUINEA COURSES Senegal bia SIERRA LEONE Monrovia BOUNDARIES Gam WATER W° WATER CAPITALS 15 HYDRONIGER LIMITS Nouakchott HYDRONIGER Freetown SENEGAL Bissau Conakry SELECT PERENNIAL INTERMITTENT BASIN NATIONAL INTERNATIONAL W° 15 14 Banjul N° N° THE GUINEA- BISSAU OCEAN SELECT N° ATLANTIC 20 15 Dakar GAMBIA 10 °0 SEPTEMBER 2005 Map APPENDIXES 85 NIGER RIVER BASIN 0 100 200 300 KILOMETERS A L G E R I A INTERIOR DELTA OF THE NIGER RIVER SELECTED CITIES AND TOWNS MAURITANIA M A L I INTERNATIONAL BOUNDARIES Area of image Source: Mariko and others, 2000. Niger Note: The picture below is an example of the United States National Oceanic and Atmospheric Administration (NOAA) Advanced Very High Resolution Radiometer satellite image, used to determine the area inundated by the Sénégal annual flood, identified recently as part of a collaboration between the NIGER Bafing Ecole Nationale d'Ingénieurs (National Engineering School) and the Institut Bani de Recherche pour le Développement (Institute for Development Research) Bamako at Montpellier, France. SENEGAL BURKINA NIGERIA FASO This map was produced by the Map Design Unit of The World Bank. é The boundaries, colors, denominations and any other information shown GUINEA r Baoul on this map do not imply, on the part of The World Bank Group, any Nige TOG BENIN judgment on the legal status of any territory, or any endorsement or acceptance of such boundaries. CÔTE GHANA D'IVOIRE O 6°W 5°W 4°W 3 °W Tombouctou Goundam 0 50 100 KILOMETERS Diré 16°N 16°N Niafunké MAURITANIA Bambara-Maoudé Léré M A L I Youvarou Korientzé Nampala 15°N Douentza 15°N OPEN WATER FLOODED SPARSE VEGETATION Ténenkou Mopti FLOODED ABUNDANT VEGETATION DRY SOILS COVERED BY VEGETATION Niono BARE SOILS STUDY AREA 14°N Koro 14°N Djenné AUGUST Segou BURKINA FASO IBRD San 2005 34135 6°W 5°W 4°W 3 °W Map 15 86 THE NIGER RIVER BASIN: A VISION FOR SUSTAINABLE MANAGEMENT Appendix 2: Technical Supporting Information Table A2.1 Climate Characteristics of the Upper Niger and Middle River Guinea Mali Parameter Macenta Kankan Siguiri Bamako Ségou Mopti Timbuktu T° average year 24.0 26.0 26.9 28.5 28.6 27.7 29.1 T° x months (x)a (3)34.6 (3)36.2 (3)38.0 (4)39.4 (4)41.2 (5)40.0 (5)43.2 T° n months (n)a (12)14.0 (12)14.2 (1)13.8 (1)17.6 (1)15.4 (1)14.0 (1)13.0 Üx year%b 96 90 85 73 74 75 54 Ün year%b 58 45 39 33 32 31 21 1 /2 (Üx Ün) 69 51 40 26 31 30 21 (April) % March 1 /2 (Üx Ün) 85 82 81 79 80 78 68 % August Rainfall avg. (mm) 2,100 1,510 1,250 985 650 415 180 No. of dry monthsc 1­2 4­5 6 7 8 8­9 10 Source: Olivry and others 1995. Note: T° temperature. a. Numbers between parentheses indicate the number of months at maximum tempera- ture (x) and minimum temperature (n). b. Üx and Ün are maximum and minimum averages of annual relative humidity. (Üx Ün)/2 corresponds to average relative humidity in the driest month (March) and wettest month (August). c. According to the definition by Gaussen, a month is considered dry when precipitation 2 Tº C. APPENDIXES 87 Table A2.2 Annual Evaporation in the Niger Basin millimeters Headwaters in Upper Guinea 1,200­1,400 Upper Guinea Plains 1,500 Southern Bani Basin, Sankarani 1,500 Malian Niger Koulikoro-Segou 1,700 Middle Bani Mopti Area 2,000 Niger River Loop, Tossaye, Gao 2,300­2,500 Northeast Burkina, Kandadji 2,350­2,450 Southern Niger, Northern Nigeria, Sokoto 1,900­2,000 Southern Jos Plateau, Adamawa 1,400 Jebba, Baro, Makurdi 1,500 Northern Benue Cameroon, Gongola 1,900­2,000 Onitsha, Lower Niger 1,200 Niger Delta 1,000­1,100 Source: Pouyaud 1986. 88 THE NIGER RIVER BASIN: A VISION FOR SUSTAINABLE MANAGEMENT Figure A2.1 Histograms of the Average Monthly Rainfall (mm) in the Upper and Middle Niger River Basin 400 400 BAMAKO TIMBUKTU 300 300 mm 200 mm 200 100 100 0 0 J F M A M J J A S O N D J F M A M J J A S O N D 400 400 SIGUIRI MOPTI 300 300 mm 200 mm 200 100 100 0 0 J F M A M J J A S O N D J F M A M J J A S O N D 400 400 KANKAN SAN 300 300 mm 200 mm 200 100 100 0 0 J F M A M J J A S O N D J F M A M J J A S O N D 400 400 KISSIDOUGOU SIKASSO 300 300 mm200 mm 200 100 100 0 0 J F M A M J J A S O N D J F M A M J J A S O N D 400 BOUNDIALI 300 mm200 100 0 J F M A M J J A S O N D Source: Olivry 2002. APPENDIXES 89 Figure A2.2 Average Monthly Relative Humidity and Evaporation at Kandadji from 1976 to 1983 60 400 50 40 mm % 300 30 20 10 200 June July Aug. Sept. Oct. Nov. Dec. Jan. Feb. March April May 60 400 50 40 mm % 300 30 20 10 200 June July Aug. Sept. Oct. Nov. Dec. Jan. Feb. March April May Evaporation (right axis) Relative humidity (left axis) Source: Pouyaud 1986. 90 THE NIGER RIVER BASIN: A VISION FOR SUSTAINABLE MANAGEMENT Figure A2.3 Seasonal Variations in Monthly Means for Temperature in Mopti and Timbuktu 36 Timbuktu 34 Mopti 32 30 C 28 26 24 22 20 Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec. Source: Olivry 2002. Figure A2.4 Seasonal Variations in Monthly Means of the Relative Humidity in Mopti and Timbuktu 80 Timbuktu 70 Mopti (%) 60 50 humidity 40 Relative 30 20 Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec. Source: Olivry 2002. Table A2.3 Hydrologic Parameters Calculated by Decade, 1951 to 1989, at Three Major Stations in the Basin: Koulikoro (Niger), Makurdi (Benue), and Onitsha (Niger) Decade Decade Decade Decade Average Average for Balance time frame 1951­60 1961­70 1971­80 1981­89 1951­80 1951­89 Niger to Koulikoro Flow rate (m3/s) 1,800 1,600 1,260 795 1,555 1,378 Volume (km3) 57 50 40 25 49 43 Rain (mm) 1,611 1,529 1,403 1,268 1,514 1,457 Runoff (mm) 473 420 331 209 408 362 Flow deficit (mm) 1,138 1,109 1,072 1,059 1,106 1,095 Flow coefficient (%) 29.4 27.5 23.6 16.5 26.9 24.9 Benue to Makurdi 91 Flow rate (m3/s) 3,294 3,684 3,097 2,609 3,358 3,185 Volume (km3) 104 116 98 82 106 101 Rain (mm) 1,312 1,294 1,218 1,094 1,275 1,233 Runoff (mm) 347 388 326 274 353 335 Flow deficit (mm) 965 906 892 820 922 898 Flow coefficient (%) 26.4 30.0 26.8 25.0 27.7 27.2 Niger to Onitshaa Flow rate (m3/s) 6,771 6,689 5,387 4,629 6,282 5,900 Volume (km3) 214 211 170 146 198 186 Rain (mm) 1,092 1,011 940 871 1,014 981 Runoff (mm) 194 192 155 133 180 169 Flow deficit (mm) 898 819 785 738 834 812 Flow coefficient (%) 17.8 19.0 16.5 15.3 17.8 17.2 Source: Mahé 1993. a. The outflow to the Lower Niger can be measured at Onitsha. 92 THE NIGER RIVER BASIN: A VISION FOR SUSTAINABLE MANAGEMENT Table A2.4 Decrease in Rainfall and Flow over Last Four Decades at Koulikoro and Douna (a) Koulikoro on the Niger (Watershed area: 120,000 km2) Flow Flow Rain Flow Flow rate Rain Runoff coefficient index index deficit Periods (Q m3/s) (mm) (mm) (%) (%) (%) (mm) 1951­60 1,800 1,611 473 29.4 128.6 107.8 1,138 1961­70 1,600 1,529 420 27.5 114.3 102.3 1,109 1971­80 1,260 1,403 331 23.6 90.0 93.9 1,072 1981­89 795 1,268 209 16.5 56.8 84.9 1,059 (b) Douna on the Bani (Watershed area: 101,600 km2) Flow Flow Rain Flow Flow rate Rain Runoff coefficient index index deficit Periods (Q m3/s) (mm) (mm) (%) (%) (%) (mm) 1961­70 649 1,187 201 16.9 139.6 106.6 986 1971­80 247 1,053 76.4 7.3 53.1 94.6 977 1981­89 163 945 50.4 5.3 35.1 84.9 895 Source: Mahé and Olivry 1995. Note: Q discharge. Table A2.5 Hydrologic Parameters and Percent Deviation from 1950 to 1969 and from 1970 to 1989 at Select Sites Flow rate Flow rate Flow rate Area Rainfall (m3/s) Rainfall (m3/s) Rainfall (m3/s) Niger (km2) (mm) 1950­69 Kf (%) (mm) 1970­89 Kf (%) (mm) % change Kf (%) Siguiri 67,600 1,735 1,236 33.3 1,464 755 24.1 15.6 38.8 27.6 93 Baro 12,770 1,974 271 33.9 1,740 189 26.8 11.9 30.3 20.9 Kankan 9,260 1,974 211 35.1 1,762 160 29.8 10.7 24.1 15.1 Douna 102,000 1,249 685 17.0 1,024 218 6.6 18.0 68.1 61.1 Koulikoro 120,000 1,633 1,719 27.7 1,374 1,048 20.0 15.9 39.0 27.8 Source: Mahé and Olivry 1995. Note: Kf flow coefficient. Table A2.6 Niger River Monthly and Annual Flow at Siguiri from 1950 to 1999 cubic meters per second Year Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec. Annual 1950 184 111 60.3 43.9 63.2 116 630 1,930 3,770 3,650 1,480 469 1,050 1951 241 145 108 74.9 198 432 1,240 2,680 3,820 3,700 3,640 1,130 1,460 1952 477 266 148 89.4 92.1 185 1,030 2,340 3,400 3,690 1,490 550 1,150 1953 320 176 132 89.9 110 605 1,680 3,300 4,350 3,720 1,540 684 1,400 1954 379 226 146 155 186 528 1,540 2,910 4,530 3,470 2,220 1,130 1,460 1955 483 264 197 148 198 704 1,720 3,120 4,710 4,280 1,970 879 1,560 1956 440 252 166 129 91.6 206 857 1,710 3,640 3,090 1,170 525 1,020 1957 260 134 85.9 48.5 66.3 307 1,190 2,680 4,470 4,680 2,390 794 1,430 1958 400 219 104 117 261 783 967 1,370 3,340 3,190 1,680 960 1,120 1959 403 210 109 65.1 87.5 360 1,270 2,180 4,470 2,760 1,330 519 1,150 94 1960 247 123 70.8 54.4 85.9 312 1,060 3,050 4,490 3,420 1,530 558 1,250 1961 263 128 66.9 41.8 74.6 107 841 2,270 3,410 2,070 771 308 866 1962 145 72 39.9 32.5 90.1 214 953 2,710 5,300 4,060 1,900 732 1,360 1963 338 208 109 63.5 116 146 669 1,990 3,390 4,110 1,690 522 1,120 1964 239 113 56.8 38.8 48.3 453 1,070 2,430 3,760 3,570 1,140 643 1,130 1965 333 171 108 82.6 89.7 336 1,420 2,040 3,460 2,980 1,220 421 1,060 1966 192 128 84.5 74.5 71.8 164 498 2,200 3,200 3,410 1,570 537 1,020 1967 245 135 91.2 52.4 100 151 766 2,480 4,780 5,740 2,060 696 1,450 1968 350 194 113 81.7 122 769 933 2,520 3,260 2,620 1,270 635 1,070 1969 275 136 87.1 66.1 60.4 306 1,570 2,850 5,040 4,830 3,030 759 1,590 1970 348 176 99.8 76.9 62.7 147 491 1,960 3,540 1,910 828 397 838 1971 160 66.9 42.8 34.5 57.2 133 686 3,120 3,940 2,240 700 440 973 1972 155 78.9 39.4 51 112 214 1,210 1,890 2,830 2,230 925 443 881 1973 163 76.6 35.1 31.3 36 159 326 1,890 2,490 1,480 822 242 648 1974 106 50.6 30.5 22.9 26.5 86.7 1,010 2,440 4,370 3,140 922 308 1,050 1975 128 67.4 30.6 26.5 71.5 183 1,100 2,130 3,910 3,430 1,230 435 1,070 1976 162 78.1 41.3 24.6 65.1 242 681 2,090 2,820 3,650 2,810 741 1,120 1977 313 138 75 35.1 36.3 113 416 1,220 2,400 1,810 664 237 623 1978 108 67.2 45.7 44.7 60.2 385 837 1,730 3,230 2,590 1,090 361 882 1979 162 64.4 29.2 24.8 32.7 317 1,450 3,000 2,940 2,240 1,080 370 982 1980 161 80.2 34.3 16.5 28.9 97 331 1,480 2,540 1,180 816 349 593 1981 135 65.4 26.1 30.2 127 182 948 2,340 2,990 1,990 697 249 819 1982 112 55.2 28.3 29.8 89.6 178 682 1,580 2,260 1,410 721 219 616 1983 94 46.8 26.2 18.5 25.9 295 692 1,490 2,440 1,610 544 194 626 1984 82.5 38.3 21.9 16.4 44.4 125 529 1,710 1,490 1,310 438 160 499 1985 65.6 29.3 11.8 8.08 9.54 22.8 472 1,970 2,940 1,820 491 165 670 1986 61 24.8 8.51 6.11 9.9 32.4 238 1,280 2,760 1,690 614 185 577 1987 72.1 32.7 9.09 4.39 7.85 192 469 1,370 2,090 1,950 673 218 594 95 1988 78.7 32.6 10.3 6.11 4.52 32.8 346 1,580 2,840 1,130 417 132 551 1989 47.7 19.5 8.65 6.58 7.22 59.6 235 1,090 2,020 1,620 510 204 486 1990 68.8 22.3 9.6 6.93 20.6 64.3 399 1,446 2,144 1,451 538 195 531 1991 73.0 22.1 10.4 8.24 7.25 72.5 437 1,418 2,008 1,587 679 217 545 1992 82.3 32.2 12.1 7.40 6.87 105 567 1,341 2,135 1,379 554 190 534 1993 75.8 25.8 15.4 11.2 13.6 75.5 317 1,494 1,889 1,424 775 281 533 1994 96 34.8 16.8 10.3 10.8 196 731 1,876 3,580 3,218 2,179 531 1,040 1995 190 81.9 32.8 30.0 50.4 134 443 2,209 3,771 3,028 1,179 400 962 1996 155 83.5 31.4 21.4 49.3 156 529 1,752 3,180 2,620 967 313 822 1997 121 55.0 19.9 12.5 30.0 154 711 1,532 2,807 2,068 944 322 731 1998 121 51.4 23.9 12.6 21.0 176 614 2,133 3,062 2,484 881 270 965 1999 106 44.4 19.9 13.3 16.7 49 380 1,370 3,171 2,675 1,445 467 941 Average 200 103 58.6 44.0 67.1 231 804 2,054 3,304 2,708 1,244 454 948 Sources: Mahé and Olivry 1991; Sangaré 2001. Note: Shaded figures indicate calculated flows. Table A2.7 Niger River Monthly and Annual Flow at Kouroussa, 1950­2000 cubic meters per second Year Jan Feb. March April May June July Aug. Sept. Oct. Nov. Dec. Annual 1950 34.0 23.0 15.5 13.0 11.0 37.6 162 157 535 649 236 76.6 189 1951 52.5 32.2 24.4 17.4 33.5 94.8 324 527 760 709 916 203 361 1952 86.7 46.8 24.5 13.4 15.8 50.1 230 346 639 751 256 101 243 1953 65.7 32.0 21.7 11.8 18.8 126.2 386 738 988 912 355 151.1 371 1954 106 82.9 70.6 72.0 34.3 109 224 350 703 672 540 292 307 1955 131 69.8 37.1 26.2 35.8 176 347 484 1,121 982 481 266 396 1956 130 85.6 45.6 27.2 20.9 74.2 208 304 561 433 212 105 199 1957 46.3 19.4 10.1 4.6 6.1 44.9 217 486 1,040 1,065 499 194 357 1958 110 56.7 26.7 21.2 39.9 121 138 192 636 774 399 256 260 1959 122 47.3 23.4 7.9 10.7 97.7 225 316 681 429 276 113 218 96 1960 56.1 20.1 8.3 4.4 7.0 153 349 953 1,098 673 283 119 365 1961 52.4 23.4 11.1 5.0 4.2 5.6 207 531 789 383 194 88.3 222 1962 40.3 17.0 13.5 23.2 50.4 86.6 304 550 928 671 368 179 317 1963 94.0 51.9 22.5 9.6 14.2 16.5 182 446 716 940 353 143 284 1964 69.8 26.8 10.7 5.2 8.5 98.7 236 421 820 808 298 148 286 1965 79.3 33.2 15.0 6.5 8.8 56.3 335 699 1,189 1,187 439 129 406 1966 36.1 24.0 15.5 11.0 8.4 54.3 150 322 613 813 381 225 259 1967 151 44.1 12.1 7.0 10.7 83.5 163 441 953 1,107 369 149 329 1968 76.5 47.3 19.8 10.3 20.1 142 192 494 809 590 256 143 268 1969 65.7 27.8 15.2 9.6 7.8 54.1 251 530 941 1,091 538 180 362 1970 86.3 41.3 18.8 9.73 8.25 17.7 113 235 697 401 214 102 182 1971 39.7 15.7 7.49 4.36 9.87 33.3 151 723 758 480 173 118 246 1972 42.4 16.7 7.51 7.11 12.8 129 341 455 673 530 401 142 270 1973 51.9 14.6 7.45 3.37 5.76 55.8 134 471 542 378 219 83.5 190 1974 30.5 13.2 7.46 4.14 40.4 29.1 226 549 946 767 334 98.0 300 1975 39.3 17.2 10.75 6.33 10.4 32.1 172 566 905 886 652 117 336 1976 53.6 19.0 9.10 4.32 11.3 87.3 171 491 626 820 636 181 304 1977 84.3 30.2 14.00 6.15 8.27 24.3 72.7 255 541 400 143 47 151 1978 31.0 16.7 9.77 6.41 24.0 65.9 173 371 774 612 322 98 246 1979 45.1 16.1 7.26 4.34 5.9 62.6 301 699 650 522 320 100 267 1980 54.7 21.4 8.03 3.97 3.74 27.0 78.8 293 555 266 190 95 152 1981 38.1 20.0 7.08 4.90 30.9 104 282 528 650 541 425 70 264 1982 32.1 14.1 7.12 4.86 15.4 48.8 171 374 513 309 234 63 174 1983 28.7 12.0 5.99 4.02 5.86 69.2 165 316 555 306 147 55.0 163 1984 22.0 10.7 5.76 3.70 7.40 35.9 161 404 358 283 166 48 147 1985 19.1 8.60 4.89 2.49 1.15 2.29 36.5 463 650 414 178 49 180 1986 18.8 7.74 4.11 2.40 2.0 22.5 95.7 306 614 380 208 54 169 1987 14.3 9.40 4.20 2.22 1.7 51.4 263 443 479 447 51.1 62 180 1988 20.0 10.0 5.17 2.44 1.07 3.15 114 374 587 207 94.8 28.3 142 97 1989 13.0 7.16 3.91 1.52 1.6 27.4 95.2 262 465 362 183 59 146 1990 13.1 8.4 4.1 2.4 2.4 3.3 65.1 259 488 323 133 50.7 113 1991 18.2 7.3 3.5 1.8 1.8 7.2 54.2 198 317 316 130 42.6 92 1992 13.3 6.1 2.8 1.6 3.2 14.5 55.9 247 411 322 125 44.9 104 1993 16.6 11.1 10 5.7 2.2 61.2 37.8 332 387 258 123 41.6 108 1994 13.1 11.9 11.2 4.3 2.2 51.8 149 413 750 838 478 117 237 1995 49.6 24 12.2 7.8 11.2 30.2 104 179 275 253 122 38 92 1996 56.5 29.8 16 9.9 10.9 30.5 136 442 658 576 186 79.5 186 1997 36.9 19.7 10.1 5.8 5.4 31.2 107 217 562 540 259 85.2 157 1998 37 17 8 3.6 3.8 34.7 142 424 547 548 171 59.7 167 1999 25 10.9 5.4 3.6 3.2 12.4 54.9 168 460 533 234 75.9 133 2000 34.4 16.9 8.4 5.2 5.6 37.2 152 387 850 905 350 124 240 Average 52.6 25.4 13.5 8.76 12.3 57.4 180 414 682 595 299 112 232 Sources: Mahé and Olivry 1991; Sangaré 2001. Note: Shaded figures indicate calculated flows. Table A2.8 Monthly and Annual Flows of the Niandan at Baro from 1948 to 2000 cubic meters per second Year Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec. Annual 1948 24.6 13.6 9.8 7.43 47.1 198 372 640 825 459 276 99.2 248 1949 49.1 32 23.7 16.3 15.6 25 93.8 391 907 383 251 93.5 190 1950 33.2 40 25.4 22.7 25.1 39.8 132 318 785 562 244 91.4 193 1951 59.5 26.4 33.5 20.4 39.5 184 488 739 683 853 743 188 338 1952 101 39.1 36.4 22.9 30 76.4 272 582 814 811 352 133 272 1953 37.6 20.3 23.4 22.7 34.5 291 448 743 928 704 365 180 316 1954 95.4 58.1 37.2 59.2 72.8 185 378 512 851 672 533 270 310 1955 126 65.7 71 49 88.3 242 523 731 1,080 732 378 196 357 1956 103 59.7 44.5 41.5 67.9 84.9 326 303 751 511 217 128 220 1957 61.2 33.5 27.8 13.3 30.3 153 499 609 990 857 423 172 322 98 1958 95.9 52.7 34.6 56.8 127 359 295 215 801 651 472 253 284 1959 109 55.4 29.8 21.3 48.9 158 411 519 866 510 351 136 268 1960 68.9 36.5 19.3 14.8 31.3 147 356 754 902 598 332 129 282 1961 63 35.7 14.5 9.35 31.7 44.9 267 489 481 373 176 67.9 171 1962 31.8 10.2 4.13 4.42 42.2 96.3 198 793 1,150 620 383 193 294 1963 93.1 61.3 31 29 46 48.8 238 404 632 753 253 91.7 223 1964 43.9 20.2 6.23 4.3 20.7 144 309 535 793 565 269 166 240 1965 79.5 53.4 26.7 19.8 37.1 231 500 292 668 447 212 78.4 220 1966 37.0 20.6 14.5 6.76 21.2 115 267 485 429 537 295 91.4 193 1967 43.4 21.9 14.6 6.54 24.8 49.9 182 371 819 894 417 161 250 1968 75 52.2 28.5 23.3 41.4 339 290 603 952 633 351 185 298 1969 87.4 45 32.4 24.1 27.1 139 614 763 943 991 502 162 361 1970 88.2 49.5 35.1 30.4 23.1 47.3 162 326 606 365 206 101 170 1971 44.5 23.4 10.7 10.5 27 110 211 697 808 454 180 123 225 1972 53.3 27.4 10.3 38.9 61.9 248 394 544 666 588 223 129 249 1973 55.1 27.6 8.92 6.31 14.7 82.7 168 375 551 342 221 58.5 159 1974 26.8 12.7 3.87 12.8 8.03 35.3 349 537 978 621 203 77.3 239 1975 36.2 13.5 4.36 2.25 28.7 48.3 183 437 879 638 321 120 226 1976 57.1 30.0 20.8 15.7 36 90.6 145 172 393 779 612 184 211 1977 88.8 48.1 33.0 25.5 45.1 65.2 143 299 583 368 166 56 160 1978 25.5 12.0 8.7 4.85 15.1 190 310 480 713 585 315 113 231 1979 60.4 31.9 13.9 9.32 15.4 166 671 818 664 596 339 122 292 1980 60 33.3 12.9 3.79 4.72 36.9 127 381 502 295 263 111 153 1981 46.3 21 8.48 17.4 68.5 103 348 713 734 559 182 62.9 239 1982 40.7 22.2 8.94 12.2 51.2 103 271 365 454 347 125 56.0 155 1983 25.6 12.0 8.7 9.09 22.5 155 197 430 523 386 173 57.0 167 1984 26.1 12.3 8.9 7.80 20.7 63.6 110 505 295 302 131 28.1 126 1985 11.8 4.2 3.4 3.66 2.03 7.42 131 457 617 258 105 40.6 137 1986 10 2.75 0.853 0.772 0.866 15.6 74 386 576 373 203 45.8 141 1987 20.6 9.2 6.8 6.83 19.4 80.7 184 390 475 430 144 57.0 152 99 1988 26.1 12.3 8.9 5.75 17.9 11.2 44 387 516 248 113 13.8 117 1989 4.8 0.2 0.7 1.79 12.4 35.6 71 352 442 441 143 30.6 128 1990 12.7 8.7 5.0 3.5 3.5 35.9 57.7 225 423 280 116 45.2 101 1991 20.3 9.0 6.6 5.50 17.5 89.8 129 374 329 463 173 44.3 138 1992 19.8 8.7 6.5 3.61 14.9 89.8 201 376 425 311 173 29.2 138 1993 12.4 4.5 3.6 3.21 14.4 35.9 93 455 421 378 234 56.4 143 1994 25.8 12.1 8.8 3.03 14.1 62.8 109 267 787 729 497 102 218 1995 48.3 25.0 17.4 7.42 20.2 22.4 123 371 488 494 167 33.3 151 1996 14.4 5.7 4.4 3.74 15.1 76.6 113 321 719 888 640 158 247 1997 75.8 40.7 28.0 12.4 27.1 88.0 293 476 804 402 162 33.1 204 1998 14.3 5.6 4.4 2.07 12.8 89.6 211 570 621 495 150 25.3 183 1999 10.5 3.4 2.9 2.61 13.5 7.7 29 133 629 615 261 51.5 147 2000 23.4 10.8 7.8 4.03 15.5 88.6 532 191 317 672 234 42.9 178 Average 49.1 26.3 17.0 14.6 30.5 108 257 464 679 544 282 103 215 Sources: Mahé and Olivry 1991; Sangaré 2001. Note: Shaded figures indicate calculated flows. Table A2.9 Monthly and Annual Flow of the Milo at Kankan from 1947 to 2000 cubic meters per second Year Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec. Annual 1947 45.7 23.1 19.8 6.87 18.6 108 298 453 766 388 125 60.3 193 1948 33.1 14.8 7.69 9.02 33.2 117 419 569 628 267 186 73 196 1949 41 24.7 28.5 34 33.9 37 229 599 763 348 162 70.5 198 1950 52 35.8 21.4 13.1 30 45.2 200 271 533 547 198 73.5 168 1951 45 31.6 28.9 29.5 76.1 142 397 604 641 697 531 146 281 1952 77.3 45.5 36.4 30.6 36.9 73.8 243 598 685 585 221 94.1 227 1953 64.6 31 29.7 19.9 27.4 172 347 595 688 469 198 105 229 1954 61.3 42.1 35.2 49.5 60.9 155 407 599 678 622 379 151 270 1955 80.6 44.3 48.6 46.3 69.9 205 413 598 737 620 237 125 269 1956 68 46.2 44 46.9 39.2 64.4 167 308 509 367 139 77 156 1957 39.6 21.6 20.2 15.6 29.4 87.7 276 471 712 629 244 104 221 100 1958 55.2 34.2 18 39.4 99.3 275 286 195 605 461 219 132 202 1959 57 30.6 18.2 13.6 32.7 72.6 351 325 787 327 188 73.6 190 1960 34.3 16.9 9.51 19.9 51.4 124 270 720 828 511 219 89.8 241 1961 45.4 25.4 12.2 11.3 34.1 35.1 183 363 484 297 123 53.4 139 1962 28.4 14.8 11.9 20 42.7 72.8 254 459 774 560 268 111 218 1963 53 45.3 32.5 31 55.4 62.2 192 404 662 516 180 68.1 192 1964 32.7 17.8 10.1 10.9 16.8 103 173 498 506 429 164 121 174 1965 65.8 40.5 30 18.4 36.6 136 421 267 565 309 137 56.4 174 1966 16.5 11.8 8.84 11.40 25.8 86.3 232 461 375 391 184 63.7 156 1967 30.5 17.3 13.3 15.5 32.8 55.8 255 534 751 706 227 88.4 227 1968 43.3 26 16.3 21.3 38.2 209 200 530 571 382 210 105 196 1969 59.3 37.7 35.8 31.6 27.8 103 441 757 786 654 355 121 284 1970 67.2 38.7 36.7 41.4 39.7 73.6 167 399 613 280 139 76.4 164 1971 44.3 33.4 21.3 25.9 38.7 54.4 167 455 598 341 115 76.2 164 1972 34.4 20.8 12.2 27.8 59.9 178 292 470 585 359 138 79.7 188 1973 36.4 18.4 9.33 10.8 13.8 44.3 93.2 450 545 303 173 57.1 146 1974 32.1 15.2 10.9 10.1 9.52 27.7 290 467 795 464 145 56.8 194 1975 29.5 15.8 8.47 21.6 42.5 88.9 238 504 773 498 145 66.8 203 1976 39.1 21.7 12.7 12.5 41.4 66.7 178 374 517 616 412 109 200 1977 62.3 34.4 18 11.5 16.7 51.6 146 274 561 270 97.9 44.7 132 1978 21.2 13.9 9.03 23.8 32.3 152 247 456 654 453 203 73.5 195 1979 43.4 21.1 15.6 25.2 24.9 101 439 693 656 476 205 76.2 231 1980 45.2 32.2 15.9 10.3 24.8 55.1 111 361 470 200 135 64.6 127 1981 34.8 19.8 12.2 15.8 42.5 51.7 357 694 634 279 106 49.7 191 1982 24.4 14.4 8.55 20.7 53 67.6 253 428 518 272 127 47.2 153 1983 23.2 13.2 5.63 5.99 15.2 115 183 406 518 285 103 44.5 143 1984 20.1 8.18 5.49 5.86 22 51.6 123 481 355 215 73.5 29.7 116 1985 10.2 4.06 2.18 2.6 5.09 16.4 170 603 680 332 95.1 35.8 163 1986 14.6 5.98 3.05 3.63 8.75 16.7 97.3 361 556 274 124 38.8 125 1987 17.8 8.99 3.73 2.41 5.39 62.5 174 366 484 322 82.3 44.5 131 1988 15.2 5.15 2.67 1.99 2.18 13.6 76.4 362 513 169 60.8 22.4 104 101 1989 5.73 3.44 2.18 1.18 4.52 30.8 95.4 327 460 332 81.8 31 115 1990 9.7 3.05 1.25 1.48 15.7 31 101 335 407 220 80.7 33.3 103 1991 14.6 7.4 3.9 2.12 17.2 68.9 136 349 379 350 103 38 122 1992 10.1 4.7 1.49 0.594 6.43 68.9 186 351 448 222 103 30.3 119 1993 9.14 3.62 1.67 7.61 9.1 31 111 431 445 279 146 44.2 127 1994 8.7 2.5 0.8 0.6 1.6 49.9 122 242 707 574 331 67.6 176 1995 19.2 4.5 2.8 7.7 18.1 21.5 132 346 493 376 98.7 32.4 129 1996 10.4 4.9 6 12.3 18.3 59.6 125 296 658 708 432 96.2 202 1997 31.2 8.2 1.7 0.4 9.1 67.6 250 452 719 299 95.5 32.3 164 1998 6.4 2.1 0.3 0.3 13.9 68.7 193 546 588 377 86.9 28.3 159 1999 21.6 9.67 4.93 5.13 8.31 11.2 66.1 107 594 478 165 50.8 127 2000 11.1 2.1 0.1 0.9 7.4 68 417 166 370 526 146 37.3 146 Average 35.2 20.0 14.4 16.0 29.2 81.6 229 439 599 412 179 70 177 Sources: Mahé and Olivry 1991; Sangaré 2001. Note: Shaded figures indicated calculated flows. Table A2.10 Interannual Volumes (1992 to 1997) at Main Stations in the Inland Delta of the Niger cubic meters per second May June July Aug. Sept. Oct. Nov. Dec. Jan. Feb. March April Annual Ké Macina 101 193 548 1,642 3,112 3,076 1,504 597 267 137 92.2 84 948 Douna 2.46 21.3 70.3 455 880 773 382 119 39 17.3 6.66 2.7 231 102 Nantaka 82 131 357 1,100 1,970 2,130 1,410 756 310 166 114 96.6 701 Akka 101 127 279 802 1,394 1,796 1,968 1,554 884 418 175 107 800 Awoye 0 0 9.31 72.8 158 224 260 192 87.8 27.8 4.34 0 86.3 Korientze 0 0 0 23.4 100 175 176 99.6 44 4.56 0 0 51.9 Diré 78.3 85.7 228 731 1,346 1,686 1,722 1,520 1,001 500 204 99.2 767 Source: Picouet 1999. Table A2.11 Niger River Monthly and Annual Flows in Mali cubic meters per second Banankoro Year May June July Aug. Sept. Oct. Nov. Dec. Jan. Feb. March April Annual 1991­92 5.3 65.3 415 1,330 1,900 1,590 700 233 87.3 34 9.6 2.5 532 1992­93 4.9 105 543 1,250 2,040 1,360 583 205 79 25.9 14.9 8.5 521 1993­94 12.9 69 297 1,410 1,770 1,410 791 296 105 37.3 17.1 7.1 521 1994­95 9.5 217 704 1,810 3,630 3,390 2,110 549 225 97 42.3 38.1 1,070 1995­96 56.9 141 421 2,160 3,840 3,180 1,170 417 181 99 40 24.6 978 1996­97 55.5 168 506 1,680 3,190 2,740 971 329 136 62.9 22 10.5 823 1997­98 32.5 165 684 1,450 2,780 2,120 949 339 137 58.4 28.2 10.7 730 103 1997­98 21.7 192 589 2,080 3,060 2,580 890 286 -- -- -- -- -- Koulikoro 1991­92 113 215 642 1,470 2,510 2,250 1,020 383 186 137 132 139 767 1992­93 141 264 755 1,430 2,850 2,000 870 383 186 118 125 142 775 1993­94 173 245 522 1,550 2,160 1,980 1,060 47 189 123 131 130 732 1994­95 133 409 1,020 1,940 4,250 5,080 3,050 891 364 219 178 191 1,480 1995­96 197 367 509 2,320 4,920 4,320 1,540 630 323 232 173 170 1,310 1996­97 253 301 526 1,820 3,700 3,660 1,350 448 191 118 98.5 112 1,050 1997­98 163 308 959 1,800 3,800 2,910 1,230 466 195 140 119 143 1,020 1997­98 162 367 772 2,190 4,120 3,910 1,290 477 -- -- -- -- -- (Table continues on the following page.) Table A2.11 (continued) Ké Macina Year May June July Aug. Sept. Oct. Nov Dec. Jan Feb March April Annual 1991­92 30.7 140 494 1,390 2,240 2,060 1,020 394 160 120 85.5 86.6 686 1992­93 73.3 150 632 1,320 2,540 1,790 818 416 190 78.8 65.9 62.7 681 1993­94 89.5 120 412 1,400 1,930 1,820 1,050 507 197 71.9 75.5 60.6 647 1994­95 61.6 253 954 1,850 3,640 4,530 2,790 851 385 205 138 131 1,320 104 1995­96 117 264 376 2,040 4,280 4,050 1,530 698 328 218 127 109 1,180 1996­97 164 176 368 1,600 3,170 3,190 1,330 515 235 110 54.5 56.6 914 1997­98 85.3 203 819 1,660 3,300 2,620 1,240 525 214 113 80.5 70 911 1998­99 -- -- -- 2,180 3,540 3,400 1,290 -- -- -- -- -- -- Douna 1991­92 0.1 33.9 50.3 536 839 496 218 64.7 27.5 13.6 4.1 0.9 190 1992­93 0.4 24.9 51.7 228 682 450 152 48.7 20.3 8.6 1.9 0.1 139 1993­94 0 0 88 217 675 420 139 46.6 21.1 8.3 1.6 0.3 135 1994­95 0.1 20.3 115 881 1,400 1,540 1,040 329 85.3 42.1 21.1 10.7 459 1995­96 10.7 33 42.8 442 854 793 345 98.8 40.1 17.3 6.2 1.7 224 1996­97 1.1 28.4 54.1 509 791 663 234 70 28.3 10 2.5 0.7 200 1997­98 6.1 41 74.4 504 948 543 202 65.9 26.5 9.9 3.4 0 202 1998­99 -- -- 98 780 1,490 1,430 458 -- -- -- -- -- -- Akka 1991­92 40.2 68.1 224 829 1,330 1,590 1,490 1,030 443 206 115 85.1 621 1992­93 88.5 94.2 277 782 1,210 1,540 1,340 873 395 160 82.2 81.2 577 1993­94 92.2 92.5 216 648 1,230 1,470 1,340 965 453 172 98.1 80.4 571 1994­95 70 128 443 1,060 1,650 2,260 2,930 2,760 1,700 947 379 172 1,208 1995­96 130 174 242 739 1,480 1,940 2,330 1,770 1,070 491 206 130 892 1996­97 124 147 215 780 1,400 1,770 1,900 1,400 802 320 112 70 753 1997­98 75.05 127 380 950 1,410 1,780 1,770 1,280 722 232 81 66 739 Diré 1991­92 30.2 28.9 176 757 1,300 1,560 1,540 1,170 516 246 107 72.3 625 1992­93 66.5 55 213 748 1,180 1,520 1,390 960 449 186 76.3 47.7 574 1993­94 46.7 64.6 153 576 1,190 1,450 1,350 1,020 546 214 86.1 56.9 563 105 1994­95 42.4 47 366 1,020 1,580 1,960 2,140 2,220 1,850 1,120 468 198 1,084 1995­96 133 138 220 662 1,420 1,800 1,980 1,840 1,230 575 254 134 866 1996­97 103 124 186 648 1,360 1,700 1,750 1,560 932 404 137 59.2 747 1997­98 51.7 93.2 301 847 1,340 1,674 1,660 1,442 808 315 118 93 729 Nantaka 1991­92 50.9 99.1 306 1,150 1,880 1,850 1,080 426 191 139 96.7 82 613 1992­93 77.7 109 366 871 1,680 1,760 817 378 198 104 79 76.7 545 1993­94 81.7 96.3 280 869 1,600 1,620 934 442 206 100 93.2 76.1 536 1994­95 73.7 142 541 1,450 2,450 2,870 2,810 1,780 604 282 175 147 1,110 1995­96 126 209 290 1,160 2,240 2,550 -- 754 352 206 128 101 -- 1996­97 119 140 237 1,160 2,030 2,400 1,580 580 257 163 -- -- -- 1997­98 -- 207 576 1,260 2,080 2,310 1,390 573 264 -- -- -- -- (Table continues on the following page.) Table A2.11 (continued) Awoye Year May June July Aug. Sept. Oct. Nov. Dec. Jan. Feb. March April Annual 1991­92 0 0 3.2 76 147 188 172 103 28 1.3 0 0 60 1992­93 0 0 9.0 70 129 180 149 82 22 0 0 0 53 1993­94 0 0 2.3 53 132 169 149 94 29 0 0 0 52 1994­95 0 0 27.9 108 198 306 442 406 206 92 20.4 0 151 1995­96 0 0 5.2 64 171 248 320 218 109 33.5 1.3 0 97 1996­97 0 0 2.2 70 158 218 241 158 72 13.8 0 0 78 Korientze 1991­92 0 0 0 13.6 78 122 90 12 0.5 0.0 0 0 26 106 1992­93 0 0 0 9.7 57 113 59 9.3 0.0 0.0 0 0 21 1993­94 0 0 0 6.0 24 98 28 15.2 1.3 0.0 0 0 14 1994­95 0 0 0 20.8 144 247 307 266 81 7.2 0 0 89 1995­96 0 0 0 8.5 114 192 236 44 18.6 2.0 0 0 51 1996­97 0 0 0 72.1 164 227 251 164 74.9 0.0 0 0 79 Selingue (dam outlet) 1991­92 162 189 241 202 542 445 174 124 92.8 108 126 145 213 1992­93 146 175 197 183 720 403 145 134 64 88.9 131 144 211 1993­94 151 168 194 182 383 396 163 121 68.1 91.2 132 151 183 1994­95 148 245 270 203 553 1,116 677 179.2 88.8 118 153 164 326 1995­96 163 211 116 203 945 Source: ORSTOM/DNHE databank. Note: -- not available. Table A2.12 A.B.N/HYDRONIGER--Hydrometry--C.I.P/Niamey, Average Monthly and Annual Flows, Station: 1111500104 Malanvillea cubic meters per second Year Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec. Annual 1970 2,150 2,430 2,140 1,140 365 145 127 643 1,630 1,660 1,460 1,590 1,280 1971 1,740 1,600 796 258 89.5 50.6 216 474 1,390 1,370 1,420 1,630 915 1972 1,750 1,500 652 197 65.4 53.5 117 758 1,320 1,350 1,360 1,460 881 1973 1,330 854 322 98.5 30 18.3 111 563 1,000 1,230 1,340 1,430 694 107 1974 1,190 561 194 60.8 22.6 19.1 177 621 1,590 1,610 1,510 1,660 769 1975 1,820 1,520 589 155 55.5 31.5 144 663 1,590 1,540 1,540 1,710 943 1976 1,920 1,810 938 271 81.5 69 79.1 474 1,020 1,330 1,470 1,540 915 1977 1,710 1,810 1,300 519 146 116 154 459 1,050 1,060 1,230 1,360 903 1978 1,180 572 201 67 57.9 61.6 92.9 919 1,200 1,280 1,390 1,520 714 1979 1,660 1,460 639 178 53.5 38.9 109 614 1,640 1,660 1,580 1,680 939 1980 1,770 1,440 559 156 45.9 49.4 464 615 1,100 1,170 1,310 1,400 838 1981 1,280 1,020 -- -- -- -- -- -- -- -- -- -- 1,160 1982 1,530 898 286 62.4 25.7 -- 270 829 1,160 1,140 1,260 1,310 795 1983 1,040 481 232 -- -- -- -- 646 889 1,030 1,150 1,180 833 1984 730 281 -- -- -- -- -- 428 792 1,120 1,010 911 756 (Table continues on the following page.) Table A2.12 (continued) Year Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec. Annual 1985 494 179 50.6 9.29 2.1 5.34 158 749 1,340 1,210 1,250 1,380 572 1986 1,040 394 112 24.8 20.8 14 160 443 974 994 1,150 1,180 543 1987 831 340 109 29 11.3 23 86.4 350 759 1,020 1,050 1,120 479 1988 757 304 87.1 22.4 14.2 46.8 252 1,140 2,100 1,380 1,280 1,340 728 1989 882 337 154 -- -- 17.4 148 778 1,180 1,170 1,110 1,150 696 1990 798 305 97.5 25.1 9.36 5.74 75.3 590 1,140 1,050 1,110 1,130 530 1991 707 302 101 31.3 90.8 262 350 968 1,460 1,150 1,180 1,250 657 1992 1,020 445 177 58.6 26.5 43.6 196 782 1,330 1,070 1,130 1,180 622 1993 840 370 127 35 11.1 29.1 132 516 1,070 1,070 1,110 1,150 540 1994 901 447 152 40.6 16.9 95.4 292 1,760 2,260 1,580 1,430 1,490 875 1995 1,620 1,570 1,120 503 264 -- -- 787 1,230 1,240 1,270 1,490 1,110 108 1996 1,550 1,330 782 -- -- -- -- 1,020 1,410 1,340 1,220 1,380 1,250 1999 -- -- -- -- -- -- -- -- 2,210 1,780 1,440 1,200 1,650 2000 268 162 295 430 565 700 834 1,160 1,130 -- -- -- 617 Average 1,440 1,270 979 618 271 147 213 804 1,560 1,500 1,390 1,470 1,030 Source: http://aochycos.ird.ne/HTMLF/ORGINT/HYDRONIG/INDEX.HTM. Note: -- not available. a. Niger Malanville. Country: Benin; basin: Niger; river: Niger; area: 1 million square kilometers; altitude: 155 meters; latitude 11.52.00 N; longitude 003.23.00 E. Table A2.13 A.B.N/HYDRONIGER--Hydrometry--C.I.P./Niamey, Average Monthly and Annual Flows, Station: 1331500034 Yidere Bodea cubic meters per second Year Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec. Annual 1984 941 426 163 565 464 782 898 456 1,070 1,390 -- 1,120 -- 1985 664 300 100 384 271 565 390 1,220 1,870 1,590 1,440 1,600 775 1986 1,280 589 246 608 690 763 391 773 1,460 1,470 1,410 1,400 769 1987 1,060 511 210 -- -- -- -- 548 1,110 1,340 1,270 1,360 -- 1988 1,040 467 164 494 -- -- 561 1,800 2,980 2,170 1,600 1,570 -- 1989 1,120 507 202 564 388 680 -- 1,180 1,750 1,630 1,360 1,360 -- 1990 1,000 434 156 439 374 383 182 969 1,510 1,330 1,360 1,360 702 1991 -- -- -- -- -- 518 -- -- 1,930 1,520 1,440 1,480 -- 109 1992 1,260 627 268 702 -- -- -- -- -- -- -- -- -- 1993 845 -- -- -- -- -- -- -- 1,540 1,370 1,350 1,380 -- 1994 1,110 580 209 439 -- 151 458 2,050 2,950 2,540 1,730 -- -- 1995 1,870 1,900 1,440 604 285 226 361 1,150 1,610 1,570 1,520 1,680 1,190 1996 1,820 1,610 682 273 169 250 273 1,090 2,100 1,780 1,550 1,600 1,100 1997 1,640 1,100 459 168 -- 150 286 912 1,700 1,540 1,490 1,610 -- 1998 1,550 966 325 124 117 405 888 2,360 2,940 2,660 1,740 1,770 1,320 1999 1,830 1,510 636 214 122 162 479 1,620 3,170 2,530 1,800 1,780 1,320 2000 1,880 1,840 1,130 355 119 183 421 1,570 1,730 1,710 1,570 1,650 1,180 2001 1,750 1,470 603 181 492 135 718 1,850 2,710 2,110 1,660 1,800 1,250 2002 -- 1,400 561 -- -- -- -- -- -- -- -- -- -- Average 1,330 955 444 156 982 178 423 1,300 2,010 1,780 1,520 1,530 1,070 Source: http://aochycos.ird.ne/HTMLF/ORGINT/HYDRONIG/INDEX.HTM. Note: -- not available. a. Yidere Bode. Country: Nigeria; basin: Niger; river: Niger; latitude: 11.23.00 N; longitude: 4.08.00 E. Table A2.14 A.B.N/HYDRONIGER--Hydrometry--C.I.P./Niamey, Average Monthly and Annual Flows, Station: 1331500029 Jebbaa cubic meters per second Year Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec. Annual 1980 1,440 1,640 -- 972 -- -- -- -- -- -- -- -- -- 1981 -- -- -- -- 922 952 1,000 1,000 1,630 1,530 1,000 950 -- 1982 -- 1,180 -- 1,090 -- 935 909 1,130 -- -- 874 862 -- 1986 -- -- -- -- -- -- -- 951 687 333 -- 829 -- 1987 1,100 -- 944 747 848 -- 839 829 -- -- 863 -- -- 1988 1,030 706 -- 930 565 -- -- -- -- -- -- -- -- 1989 -- -- -- -- -- -- 364 1,160 1,610 1,850 815 1,110 -- 1990 1,050 937 895 221 505 449 149 332 856 455 -- -- -- 110 1991 -- -- -- 387 -- -- -- -- -- -- -- -- -- 1992 -- -- -- -- -- -- 411 209 -- -- -- 1,110 -- 1993 -- -- -- -- 770 612 523 538 1,120 918 530 350 -- 1994 435 -- 495 529 319 -- -- -- 2,310 3,910 1,790 -- -- 1995 1,710 2,070 1,760 1,430 1,520 -- -- 1,660 -- -- -- -- -- 1996 903 823 746 500 557 358 665 702 1,240 1,130 1,070 893 799 1997 1,210 1,230 872 947 513 -- -- -- -- -- -- -- -- Average 1,110 1,230 952 775 724 661 608 851 1,350 1,450 992 872 799 Source: http://aochycos.ird.ne/HTMLF/ORGINT/HYDRONIG/INDEX.HTM. Note: -- not available. a. Jebba. Country: Nigeria; basin: Niger; river: Niger; latitude 9.10.00 N; longitude 4.50.00 E. Table A2.15 A.B.N/HYDRONIGER--Hydrometry--C.I.P./Niamey, Average Monthly and Annual Flows, Station: 1331500002 Onitshaa cubic meters per second Year Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec. Annual 1980 2,030 2,080 1,290 1,080 1,380 2,590 4,530 10,800 16,500 14,600 6,610 2,600 5,510 1981 1,510 1,200 989 965 1,650 2,490 6,530 10,900 17,300 14,600 4,870 1,890 5,410 1982 1,730 1,590 1,090 1,530 1,690 2,390 5,530 8,060 11,900 12,100 5,570 3,270 4,700 1983 2,270 1,710 1,780 1,800 1,980 2,980 4,230 5,960 10,000 7,490 1,860 928 3,580 1984 714 695 524 699 971 2,320 4,800 7,210 10,600 8,260 3,340 1,450 3,470 1985 923 739 646 856 925 1,770 4,810 9,400 14,900 13,100 4,260 2,040 4,530 1986 1,290 993 897 1,050 1,120 2,000 3,800 7,620 11,400 12,100 5,140 1,910 4,110 1987 1,600 1,480 1,870 2,150 2,450 2,660 3,320 5,420 11,800 12,200 4,630 1,590 4,260 111 1988 1,090 947 895 1,390 1,450 2,170 3,030 5,990 14,200 16,000 5,230 2,350 4,560 1989 1,620 1,390 1,070 1,460 2,970 3,210 5,710 9,390 15,700 16,200 5,550 2,550 5,570 1990 -- -- -- -- 1,990 2,490 5,000 10,400 14,300 12,300 5,390 2,730 -- 1991 1,640 1,510 1,200 1,370 1,900 5,840 8,290 13,600 17,600 12,800 6,030 2,640 6,200 1992 1,920 1,600 1,410 -- -- -- -- -- -- -- -- -- -- 1995 -- 2,580 2,320 2,020 -- -- -- -- -- 16,200 -- -- -- 1999 -- -- -- -- 2,140 2,880 5,920 -- -- -- 14,000 4,510 -- 2000 -- -- -- -- -- -- -- -- 15,500 14,600 5,370 2,950 -- 2001 2,780 2,210 1,830 1,760 2,110 2,790 4,660 8,640 13,900 -- -- -- -- 2002 -- -- -- -- -- -- -- -- -- -- -- -- -- Average 1,620 1,480 1,270 1,400 1,770 2,760 5,010 8,720 14,000 13,000 5,560 2,390 4,720 Source: http://aochycos.ird.ne/HTMLF/ORGINT/HYDRONIG/INDEX.HTM. Note: -- not available. a. Onitsha. Country: Nigeria; basin: Niger; river: Niger; latitude 6.11.00 N; longitude 6.46.00 E. Table A2.16 A.B.N/HYDRONIGER--Hydrometry--C.I.P./Niamey, Average Monthly and Annual Flows, Station: 1331500007 Makurdia cubic meters per second Year Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec. Annual 1980 297 219 189 190 287 1,040 2,490 7,030 10,900 8,530 2,860 726 2,900 1981 305 212 194 204 530 1,010 4,100 6,870 11,300 7,750 2,160 580 2,940 1982 290 223 229 227 350 979 3,460 5,550 8,640 8,080 2,470 668 2,600 1983 346 275 230 226 265 728 2,230 3,940 7,320 3,820 704 294 1,700 1984 219 190 184 211 347 770 2,690 4,810 6,430 4,820 1,520 362 1,880 1985 230 190 174 285 308 1,140 4,080 8,050 9,130 5,720 1,380 474 2,600 1986 271 213 206 240 299 763 2,810 5,270 6,780 5,870 1,920 570 2,100 1987 269 222 212 244 257 766 1,960 3,330 7,150 6,530 1,270 410 1,890 1988 245 202 203 214 291 690 1,800 4,330 9,470 9,640 2,330 601 2,500 112 1989 272 208 188 203 659 1,370 2,720 6,290 11,100 9,690 2,390 635 2,980 1990 397 263 217 228 474 1,190 3,850 8,140 11,000 7,530 2,790 814 3,070 1991 419 260 232 266 1,120 3,220 4,260 7,760 10,800 7,340 3,010 906 3,300 1992 446 303 262 324 667 1,850 3,840 6,860 10,500 9,760 3,930 1,220 3,330 1993 548 283 -- -- -- -- -- -- -- -- -- 1,030 -- 1994 511 322 264 265 319 1,220 2,700 5,520 10,700 -- -- -- -- 1995 450 289 257 266 602 1,530 3,950 7,980 11,500 11,700 4,490 1,620 3,720 1996 922 617 -- -- -- -- -- -- -- -- -- -- -- 1998 -- -- -- -- -- -- -- -- 11,300 -- -- 2,140 -- 1999 1,320 827 775 684 637 1,210 2,870 3,430 -- -- -- -- -- 2000 -- -- -- -- -- -- -- -- -- -- -- -- -- 2002 -- 297 269 -- -- -- -- -- -- -- -- -- -- Average 535 338 287 342 615 1,560 3,440 6,230 10,100 9,550 3,080 998 2,920 Source: http://aochycos.ird.ne/HTMLF/ORGINT/HYDRONIG/INDEX.HTM. Note: -- not available. a. Makurdi. Country: Nigeria; basin: Niger; river: Benue; latitude 7.45.00 N; longitude 8.32.00 E. Table A2.17 A.B.N/HYDRONIGER--Hydrometry--C.I.P./Niamey, Average Monthly and Annual Flows, Station: 1331500014 Laua cubic meters per second Year Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec. Annual 1980 124 87.2 60.2 48.3 100 362 1,360 3,230 -- -- -- -- -- 1981 147 77.7 43.7 33.3 83.1 263 1,460 2,530 -- 2,260 1,120 716 -- 1982 371 41.5 25.0 19.1 36.3 380 1,470 2,320 -- -- 884 416 -- 1987 -- -- -- -- -- -- -- 836 1,760 1,170 222 134 -- 113 1989 -- -- -- 127 225 -- -- -- -- -- -- -- -- 1991 130 104 102 84.4 395 685 -- 3,140 -- -- -- -- -- 1992 -- -- -- -- -- -- -- -- -- -- -- -- -- 1994 -- -- -- -- -- -- -- 2,870 -- -- -- -- -- 1999 -- -- -- -- -- -- -- 2,770 -- -- -- -- -- 2000 -- -- -- -- -- 1,030 -- 3,260 3,260 2,200 991 -- -- 2001 544 498 -- -- -- -- -- -- -- -- -- -- -- Average 263 162 57.7 62.4 168 544 1,430 2,620 2,510 1,880 804 422 -- Source: http://aochycos.ird.ne/HTMLF/ORGINT/HYDRONIG/INDEX.HTM. Note: -- data not available. a. Lau. Country: Nigeria; basin: Niger; river: Benue; latitude 9.12.00 N; longitude 11.16.00 E. Table A2.18 A.B.N/HYDRONIGER--Hydrometry--C.I.P./Niamey, Average Monthly and Annual Flows, Station: 1051500020 Garouaa cubic meters per second Year Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec. Annual 1930 -- -- -- -- -- -- -- -- 1,970 -- -- -- -- 1931 -- -- -- -- -- -- -- 1,760 2,900 -- -- -- -- 1932 -- -- -- -- -- -- -- -- 2,430 -- -- -- -- 1933 -- -- -- -- -- -- -- -- 2,350 -- -- -- -- 1934 -- -- -- -- -- -- -- 2,000 1,290 -- -- -- -- 1935 -- -- -- -- -- -- -- 1,400 2,720 -- -- -- -- 114 1936 -- -- -- -- -- -- -- -- 2,540 -- -- -- -- 1938 -- -- -- -- -- -- 290 680 -- -- -- -- -- 1939 -- -- -- -- -- -- 275 949 1,120 -- -- -- -- 1941 -- -- -- -- -- -- -- -- 1,880 -- -- -- -- 1942 -- -- -- -- -- -- -- 1,100 -- -- -- -- -- 1943 -- -- -- -- -- -- 187 -- 2,140 -- -- -- -- 1944 -- -- -- -- -- -- 119 711 1,230 497 -- -- -- 1945 -- -- -- -- -- -- 190 586 1,810 700 94.1 24.1 -- 1946 7.70 2.53 1.25 -- -- 79.6 311 666 2,280 2,330 241 89.1 -- 1947 -- -- -- -- -- 50.8 233 1,330 1,940 532 79.2 6.12 -- 1948 -- -- -- -- 0.967 142 364 2,460 2,580 910 130 29.4 -- 1949 6.61 1.28 0.322 0 6.00 29.9 241 1,010 1,100 481 -- 30.9 -- 1950 11.8 2.85 0.516 -- 25.9 50.5 192 973 1,640 695 179 62.4 -- 1951 23.2 7.71 1.61 0.800 28.2 40.2 199 956 1,490 -- -- -- -- 1952 -- 6.86 1.12 0.733 10.4 55.5 199 715 1,320 1,010 174 70.3 -- 1953 29.5 14.1 6.00 1.76 35.8 79.5 401 771 1,270 566 88.3 30.2 274 1954 14.3 5.57 1.61 1.00 8.19 104 -- 592 1,930 1,060 215 95.1 -- 1955 -- 21.0 4.58 1.79 10.1 100 366 1,380 2,350 1,530 353 149 -- 1956 47.8 25.2 13.7 5.96 3.12 39.0 252 966 1,880 1,150 161 78.7 385 1957 36.5 20.5 11.4 3.46 14.0 161 399 1,040 1,690 1,070 187 67.9 392 1958 35.2 21.1 9.09 1.96 17.8 85.5 307 703 1,400 681 113 50.9 286 1959 30.8 18.6 7.77 2.26 27.9 124 232 457 2,180 626 168 41.9 326 1960 25.7 11.2 1.83 .466 15.9 76.0 595 1,870 2,820 1,190 278 117 583 1961 37.6 10.6 2.06 .333 .322 59.4 757 1,010 2,530 576 152 40.5 431 1962 14.1 2.78 .483 0 .612 99.1 202 1,140 2,350 1,080 157 73.7 427 1963 28.2 11.6 2.38 1.00 11.2 33.1 367 1,760 1,840 958 222 56.3 441 1964 24.4 12.0 3.54 10.6 13.7 49.5 283 680 1,710 850 187 71.4 325 1965 33.6 -- 6.12 1.29 2.70 98.4 306 1,770 1,590 431 82.3 30.2 -- 1966 15.1 6.10 2.12 1.76 35.1 158 234 913 2,380 555 185 57.8 379 1967 29.4 15.4 4.61 2.86 5.00 39.3 355 734 1,430 597 88.8 50.9 279 115 1968 24.4 11.0 3.22 1.00 10.1 119 438 1,080 1,800 514 90.6 37.0 344 1969 16.6 8.07 3.12 4.16 16.5 95.0 414 1,910 2,260 1,210 289 82.4 526 1970 31.6 13.4 3.48 2.29 1.58 23.0 202 1,550 2,320 896 242 78.2 447 1971 26.6 11.3 3.35 1.16 0 15.7 275 1,070 1,660 300 -- -- -- 1972 15.0 7.58 2.96 1.53 9.80 128 256 584 516 318 69.4 25.9 161 1973 9.74 2.35 .645 0 3.67 38.4 245 1,250 1,340 345 58.1 14.1 276 1974 6.61 2.17 .741 0 10.0 6.86 222 935 1,040 793 -- -- -- 1975 11.9 5.78 2.12 .433 2.25 -- 290 1,630 2,350 896 122 -- -- 1976 -- 16.7 6.58 -- -- 45.5 298 929 689 672 234 -- -- 1977 -- 9.69 3.86 .299 -- -- 277 992 1,510 254 27.9 9.21 -- 1978 7.45 2.32 -- -- 41.0 81.9 382 1,090 2,110 624 185 77.6 -- 1979 -- 8.28 -- -- -- 87.1 317 814 710 256 70.4 15.7 -- 1980 12.5 5.27 2.99 1.78 12.6 64.1 475 1,640 1,410 504 136 39.4 359 (Table continues on the following page.) Table A2.18 (continued) Year Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec. Annual 1981 16.5 6.48 1.60 0.013 0 0.245 310 657 1,300 366 -- -- -- 1982 9.14 -- -- -- -- -- 100 416 275 126 21.0 4.52 -- 1983 0 0 0 0 20.1 54.9 106 241 371 95.3 69.3 68.8 85.5 1984 66.8 71.9 83.1 80.5 79.9 79.9 111 118 159 111 77.8 67.3 92.2 1986 66.0 59.8 78.8 87.1 100 108 160 291 458 217 87.1 74.4 149 1987 69.8 73.5 77.2 83.3 88.6 119 102 175 206 101 65.4 73.6 103 1988 -- -- -- -- -- -- -- 884 1,380 931 -- -- -- 1989 79.3 71.4 71.8 75.5 59.7 71.5 101 746 599 155 86.0 68.6 182 1990 62.8 57.1 60.0 66.2 -- 66.9 283 964 368 128 82.9 73.9 -- 1991 66.5 73.6 80.4 80.7 81.8 99.0 124 1,200 894 175 135 118 261 1992 -- 1,160 673 -- -- -- -- -- -- -- -- -- -- 116 1993 84.2 82.8 80.6 74.2 74.2 75.1 108 314 296 125 76.3 68.8 122 1994 62.8 60.6 65.5 66.4 67.0 108 215 810 1,870 586 169 105 349 1995 86.0 80.6 75.2 70.7 76.3 105 470 1,740 732 276 137 97.2 329 1996 84.0 76.1 77.4 82.8 72.5 105 326 506 949 471 151 -- -- 1997 97.4 131 134 138 160 160 872 1,180 378 199 -- -- -- 1998 -- 82.3 83.0 84.7 91.4 97.4 169 930 1,690 857 154 119 -- 1999 92.5 95.1 105 98.4 133 -- -- -- -- -- -- -- -- 2000 -- -- -- -- -- -- -- -- -- -- -- 175 -- Average 36.2 52.2 39.6 26.5 33.8 78.9 287 1,010 1,550 627 142 64.0 308 Source: http://aochycos.ird.ne/HTMLF/ORGINT/HYDRONIG/INDEX.HTM. Note: -- not available. a. Garoua. Country: Cameroon; basin: Niger; river: Benue; area: 64,000 square kilometers; altitude 174 meters; latitude 9.17.00 N; longitude 13.24.00 E. Table A2.19 A.B.N/HYDRONIGER--Hydrometry--C.I.P./Niamey, Average Monthly and Annual Flows, Station: 1051500021 Cossia cubic meters per second Year Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec. Annual 1954 -- -- -- -- -- -- -- 30.0 54.2 -- 93.6 -- -- 1955 29.9 13.5 -- -- -- 76.1 126 319 495 210 168 113 -- 1956 -- -- -- -- 0 40.8 107 313 363 152 90.0 81.8 -- 1957 39.7 19.7 -- 2.66 19.2 64.9 178 307 321 200 82.2 44.2 -- 1958 27.8 13.3 6.74 1.06 15.9 78.4 109 323 299 111 43.8 29.3 88.2 1959 13.8 3.78 0.580 0 31.3 90.5 119 142 473 129 168 78.9 104 1960 33.8 12.2 1.90 0 15.3 68.9 265 410 579 139 127 96.5 146 1961 48.4 19.9 6.32 0.966 0.161 65.9 237 204 589 160 101 46.1 123 117 1962 16.2 2.50 0 0 0 62.9 109 277 393 169 81.0 94.3 100 1963 49.7 21.1 4.32 0.366 11.8 57.7 125 556 334 310 111 51.7 136 1964 24.1 13.4 4.67 16.6 13.2 76.3 106 150 -- 94.2 54.5 52.3 -- 1965 26.9 12.1 4.58 0.366 0 30.3 179 491 308 101 16.1 1.29 97.6 1966 0 0 0 0.266 7.45 37.1 82.7 268 322 121 121 51.4 84.2 1967 17.2 4.50 1.61 0.300 0 18.2 200 233 322 83.1 37.4 31.6 79.1 1968 15.9 6.41 2.70 1.36 2.87 108 164 243 296 73.5 20.8 13.8 79.0 1969 6.32 3.60 2.12 1.20 0.032 57.2 140 424 504 408 201 89.4 153 1970 42.7 14.8 5.51 1.56 3.90 29.8 79.3 339 425 523 198 77.9 145 1971 27.3 12.4 5.41 1.70 0.354 27.2 151 279 398 103 60.9 27.4 91.1 1972 14.0 7.24 2.83 0.766 18.7 125 150 266 200 128 30.5 16.7 80.0 1973 -- -- -- 0.733 0 25.9 193 463 341 88.7 21.8 7.09 -- 1974 -- 1.07 -- -- 3.90 5.33 79.7 204 224 103 -- -- -- 1975 3.09 1.21 0 0 11.0 35.2 162 393 537 103 59.2 73.8 115 1976 35.2 12.7 4.67 1.96 14.4 10.5 125 215 147 175 40.2 20.9 66.9 (Table continues on the following page.) Table A2.19 (continued) Year Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec. Annual 1977 9.13 6.32 4.13 2.41 2.02 7.65 89.5 368 290 29.8 6.46 4.42 68.3 1978 2.74 2.00 1.41 1.70 8.70 19.4 187 249 208 132 97.3 55.3 80.4 1979 14.9 6.19 2.41 0.591 7.00 41.8 135 233 149 -- -- -- -- 1980 0.813 0.372 0.301 -- -- -- 155 496 278 74.0 -- -- -- 1981 6.85 2.58 1.66 2.20 -- -- 121 157 196 43.4 19.4 10.2 -- 1982 4.55 1.56 0.620 0.593 -- 8.84 88.1 326 -- -- 10.5 3.16 -- 1983 1.16 1.18 0.398 0.351 0.174 33.2 -- -- -- 29.0 -- -- -- 1984 1.93 0.630 0.459 0.432 4.89 10.4 -- 46.5 85.5 30.3 6.62 2.82 -- 1985 0.575 -- -- 0.331 0.257 24.0 163 273 166 22.4 6.42 2.76 -- 1986 -- -- -- -- -- -- 105 255 401 71.5 23.3 10.1 -- 1987 5.62 2.07 0.524 0.402 0.435 26.1 19.6 152 114 44.8 31.1 22.1 34.9 118 1988 -- -- -- -- -- -- 139 -- 524 134 -- -- -- 1989 -- -- -- -- -- 12.3 32.8 181 143 37.4 13.4 6.80 -- 1990 2.02 0.594 0.292 0.119 0.501 30.3 211 -- 118 -- -- -- -- 1991 -- -- -- -- -- -- -- -- -- -- -- -- -- 1992 30.7 -- -- -- -- -- -- -- -- -- -- -- -- 1995 5.00 1.19 0.522 0.258 2.45 -- -- -- -- 1320 -- -- -- 1996 -- 1,400 1,420 1,460 1,520 1,490 1,580 1,590 1,120 -- -- -- -- 1999 -- -- -- -- 2.57 11.7 81.4 225 347 227 89.6 64.7 -- 2000 42.0 23.1 11.6 5.70 5.88 56.9 153 313 166 43.8 12.6 21.8 71.3 Average 18.2 49.8 49.9 47.1 52.3 84.7 174 317 331 165 68.0 40.7 97.2 Source: http://aochycos.ird.ne/HTMLF/ORGINT/HYDRONIG/INDEX.HTM. Note: -- not available. a. Cossi. Country: Cameroon; basin: Niger; river: Mayo Kebi; area: 26,000 square kilometers; altitude: 192 meters; latitude 9.36.00 N; longitude 13.52.00 E. Table A2.20 A.B.N/HYDRONIGER--Hydrometry--C.I.P./Niamey, Average Monthly and Annual Flows, Station: 1051500023 Riaoa cubic meters per second Year Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec. Annual 1950 -- -- -- -- 5.93 30.7 114 954 1,560 -- -- 17.0 -- 1951 9.80 3.92 0.935 -- -- 28.7 135 701 1,110 618 140 26.5 -- 1952 21.9 12.2 6.58 0.166 12.0 27.8 237 712 -- -- -- -- -- 1953 8.25 3.39 1.35 0.266 10.9 41.2 220 666 745 333 39.9 9.38 173 1954 -- -- 1.32 1.00 2.29 31.1 -- 569 1,520 -- 97.8 23.6 -- 1955 6.80 2.42 -- -- -- 42.7 283 1,030 1,810 1,130 161 51.9 -- 1956 22.5 -- -- -- -- -- 235 673 1,490 921 101 35.9 -- 1957 13.6 5.21 1.48 -- 5.93 112 265 752 1,240 765 90.1 13.7 -- 119 1958 1.54 -- 0 0 0.096 13.3 194 485 936 395 43.1 5.19 -- 1959 0.903 0 0 0 1.12 17.7 84.1 327 1,730 264 25.0 -- -- 1960 -- 0 0 0 2.83 26.1 328 1,220 1,990 827 96.5 14.3 -- 1961 4.61 0.964 0 0 0.290 34.1 485 794 1,460 275 29.9 7.41 258 1962 1.77 0 0 0.033 2.16 39.9 82.8 921 1,780 662 70.4 14.6 298 1963 5.29 0.964 0 0.466 4.83 9.86 269 1,180 1,090 554 88.1 21.4 269 1964 10.3 5.55 2.67 5.33 11.0 26.2 205 538 1,440 541 108 30.0 244 1965 12.1 7.67 4.16 2.26 4.80 37.9 143 962 1,070 249 40.4 12.7 212 1966 5.77 2.60 0.870 0 14.4 86.6 134 805 1,710 367 72.4 15.6 268 1967 7.48 3.96 1.93 1.50 3.90 19.3 187 475 947 412 40.2 11.6 176 1968 5.54 3.00 1.22 0.400 3.61 11.9 286 897 1,150 351 45.2 16.4 231 1969 8.67 4.82 2.00 4.53 11.8 56.9 294 1,410 1,590 668 88.8 18.6 347 1970 7.77 4.10 1.54 0.633 .419 10.8 159 1,360 1,660 -- -- -- -- 1971 9.90 5.17 2.64 0.766 0 13.0 198 844 1,190 168 28.6 9.16 206 (Table continues on the following page.) Table A2.20 (continued) Year Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec. Annual 1972 5.25 3.24 1.19 1.29 5.29 29.0 133 385 328 239 27.9 6.67 97.1 1973 17.6 11.7 6.83 0.600 9.22 36.3 145 705 -- 209 34.4 -- -- 1974 3.35 0.607 0 0 7.67 4.90 182 796 825 680 -- 22.1 -- 1975 13.0 7.82 4.38 2.26 -- 12.1 260 1,310 1,680 -- 83.9 30.3 -- 1976 18.6 13.0 8.67 5.69 -- 51.2 241 816 585 560 143 28.9 -- 1977 6.70 4.65 3.07 1.84 1.51 15.9 235 856 1,150 248 30.2 10.0 214 1978 14.3 9.35 5.22 7.80 28.0 50.9 190 962 1,770 463 -- -- -- 1979 16.2 10.0 6.32 4.61 20.5 57.2 146 552 498 153 -- 30.5 -- 1980 -- -- -- -- -- 23.0 301 1,180 911 -- -- -- -- 1981 12.2 8.14 5.05 -- 4.60 17.0 170 503 1,000 253 51.5 20.4 -- 1982 10.2 6.09 4.37 -- -- 11.9 13.1 3.32 3.44 -- -- 1.44 -- 120 1983 4.98 15.6 -- 17.6 53.7 45.1 46.3 47.9 217 60.3 51.2 -- -- 1984 64.9 73.3 89.8 -- 56.7 61.9 49.9 36.6 49.7 53.9 51.5 27.2 -- 1985 32.4 28.6 27.0 23.9 -- -- 75.3 46.8 56.0 -- -- -- -- 1986 52.8 65.0 77.4 90.5 84.3 73.7 60.1 40.2 53.3 51.7 47.3 46.8 61.9 1987 -- -- 60.5 91.0 110 109 123 30.3 24.7 17.5 9.28 -- -- 1989 -- -- -- -- -- 35.2 -- -- -- -- -- -- -- 1990 34.2 29.4 34.2 36.9 -- 31.3 82.5 806 197 32.3 30.0 13.7 -- 1991 13.5 31.2 38.4 38.5 24.0 31.7 23.4 1,050 311 13.1 12.5 19.0 134 1992 27.1 25.4 25.1 18.1 -- -- 33.0 -- -- -- -- -- -- 1995 15.4 -- -- -- -- -- -- -- -- -- -- -- -- 1999 -- -- -- -- 10.4 -- -- -- -- -- -- -- -- Average 14.3 11.7 11.8 11.2 16.1 36.3 176 710 1,020 392 63.8 19.7 212 Source: http://aochycos.ird.ne/HTMLF/ORGINT/HYDRONIG/INDEX.HTM. Note: -- not available. a. Riao. Country: Cameroon; basin: Niger; river: Benue; area: 27,600 square kilometers; altitude: 185 meters; latitude 9.03.00 N; longitude 13.42.00 E. Table A2.21 A.B.N/HYDRONIGER--Hydrometry--C.I.P./Niamey, Average Monthly and Annual Flows, Station 1051500024 Buffle Noira cubic meters per second Year Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec. Annual 1955 -- -- -- -- -- -- -- -- -- 223 27.7 9.51 -- 1956 5.09 -- -- -- -- -- 49.0 186 259 131 14.8 6.74 -- 1957 3.25 1.67 .967 1.60 4.45 -- -- 175 -- -- 30.7 9.58 -- 1958 4.54 2.10 .935 1.79 4.29 12.6 64.0 94.9 206 91.6 15.8 6.54 42.1 1961 5.87 2.89 1.12 1.03 3.32 30.7 110 82.5 161 66.3 12.8 5.41 40.3 1962 2.80 -- -- -- 6.80 34.4 59.3 127 190 98.1 22.5 7.87 -- 1963 3.77 1.82 0.806 1.79 7.06 6.56 36.1 267 179 105 18.2 7.29 52.9 1964 3.64 1.51 -- -- 5.64 17.2 82.4 102 255 89.4 28.0 9.06 -- 121 1965 4.45 1.82 1 0.800 2.35 11.8 48.6 165 220 57.5 12.1 5.19 44.2 1966 2.48 1.03 0.419 1.39 12.5 34.0 45.0 223 283 93.3 19.8 6.03 60.2 1967 3.06 1.46 0.709 0.633 5.70 20.1 92.8 160 181 94.4 14.1 4.51 48.2 1968 2.35 1.10 0.451 3.96 4.64 10.6 73.7 198 211 58.1 11.3 3.16 48.2 1969 1.54 0.821 -- -- 4.80 25.1 89.5 249 251 77.6 22.4 6.38 -- 1970 2.64 0.750 0 0.266 5.41 14.7 62.6 208 235 57.5 12.0 4.32 50.3 1971 1.90 0.571 0 0.233 0.967 10.3 74.6 163 176 36.8 8.10 2.61 39.6 1972 1.00 0 0 0.533 7.25 16.1 45.0 106 83.3 79.0 11.6 4.45 29.5 1973 1.25 -- -- -- 4.32 8.63 32.7 115 118 38.6 7.26 2.64 -- 1974 1.00 0.071 -- 0.566 5.83 3.83 41.0 97.9 142 113 -- -- -- (Table continues on the following page.) Table A2.21 (continued) Year Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec. Annual 1975 2.48 1.03 0 0 1.25 4.03 66.7 171 247 122 15.7 6.00 53.1 1976 2.93 1.31 0.225 0 3.51 12.5 83.0 180 121 114 29.9 8.67 46.4 1977 3.83 1.41 0.389 0.079 1.29 10.8 66.8 134 172 83.3 9.05 3.51 40.5 1978 1.38 0.428 0 -- 6.51 27.2 46.6 134 177 80.1 27.1 6.45 -- 1979 -- -- -- -- -- -- -- -- -- -- -- -- -- 1980 -- 0.510 -- -- -- -- -- -- -- -- -- -- -- 1983 -- 0.867 0.217 -- -- -- -- -- -- -- -- -- -- 1984 0.301 0.109 0.039 0.461 0.971 1.01 27.1 40.1 -- -- -- 1.35 -- 1985 -- -- -- -- -- -- 9.08 26.2 -- -- 3.63 -- -- 1986 -- -- -- -- 1.93 5.74 23.9 80.7 79.5 54.0 6.47 2.07 -- 1987 0.631 -- -- -- -- -- -- 12.3 -- -- -- -- -- 122 1989 -- -- -- -- -- -- -- -- -- -- -- 2.22 -- 1990 0.946 0.360 0.021 0.326 3.00 4.41 39.6 115 100 38.0 -- -- -- 1994 -- -- -- -- -- -- -- -- -- -- -- -- -- 1995 1.88 1.18 0.652 0.588 4.01 -- -- 225 143 -- -- -- -- 1997 -- -- -- -- -- -- -- -- -- -- -- -- -- Average 2.60 1.08 0.418 0.891 4.49 14.7 57.1 142 182 87.0 16.6 5.48 45.8 Source: http://aochycos.ird.ne/HTMLF/ORGINT/HYDRONIG/INDEX.HTM. Note: -- not available. a. Buffle Noir. Country: Cameroon; basin: Niger; river: Benue; area: 3,220 square kilometers; altitude: 350 meters; latitude 8.52.00 N; longitude 13.54.00 E. APPENDIXES 123 Table A2.22 Specific Flow in the Upper Basins of the Niger River and Bani River Annual flow Suspension Dissolved solids Station and year (l/s/km2) (t/yr/km2) (t/yr/km2) Niger to Banankoro 1990 7.4 -- -- 1991 7.6 8.1 10.4 1992 7.4 6.6 11.7 Niger to Koulikoro 1990 6.1 -- -- 1991 6.4 7.4 8.0 1992 6.4 6.3 7.8 Bani to Douna 1990 1.5 2.8 -- 1991 1.9 3.2 2.7 1992 1.4 2.5 2.5 Source: Olivry and others 1995. Note: -- not available. 124 THE NIGER RIVER BASIN: A VISION FOR SUSTAINABLE MANAGEMENT Figure A2.5 TDS Concentrations and TDS Daily Flows for the Niger River at Banankoro (a) and the Bani River at Douna (b) 2,500 100 2,000 80 1,500 60 mg/l /s 3 m 1,000 40 500 20 0 0 27 5 1 4 8 14 21 31 8 17 27 5 June Oct. Jan. April Aug. Nov. Feb. May Sept. Dec. March July 1990 1991 1992 1993 (a) 1,200 120 1,000 100 800 80 mg/l /s 3 600 60 m 400 40 200 20 0 0 14 23 4 16 25 1 7 10 27 16 20 July Oct. Feb. May Aug. Dec. March June Dec. April July 1990 1991 1992 1993 (b) TDS daily flows (left axis) TDS concentrations (right axis) Source: Olivry and others 1998. Figure A2.6 Average Monthly Suspended Solids Concentrations and Monthly Flows for the Niger River at Banankoro (a), at Koulikoro (b), and the Bani River at Douna (c) 50 2,500 40 2,000 30 1,500 m 3 /s 3 gm 20 1,000 10 500 0 0 J A S ON D J F M A M J J A S ON D J F M A M J J A S ON D 1990 1991 1992 (a) 50 3,000 40 2,500 2,000 30 m 3 1,500 /s 3 gm 20 1,000 10 500 0 0 J J A S O N D J F M A M J J A S O N D 1991 1992 (b) 120 1,000 100 800 80 600 m 3 60 /s 3 gm 400 40 20 200 0 0 J A S ON D J F M A M J J A S ON D J F M A M J J A S ON D (c) TSS (left axis) Flow (right axis) Source: Olivry and others 1998. 126 THE NIGER RIVER BASIN: A VISION FOR SUSTAINABLE MANAGEMENT Figure A2.7 The Ionic Composition (average interannual ratio of each cation and anion in micro equivalent per liter) of the Niger River at Banankoro (a) and the Bani River at Douna (b) NO3 1% SO42 1% NO3 2% SO4 2 1% Cl 4% Cl 4% HCO3 HCO3 94% 93% Na Na 28% 32% Ca2 30% Ca2 34% K K 13% 10% Mg2 Mg2 28% 25% (a) Niger at Banankoro (b) Bani at Douna Source: Picouet 1999. APPENDIXES 127 Appendix 3: Overview of Data Management In 1985, the Hydrological Forecasting System in the Niger River Basin (HYDRONIGER) project became operational when the International Center for Hydrological Planning in Niamey was commissioned, under the direc- tion of the Niger Basin Authority (NBA). This project provided a reception station, installation of 65 data collection platforms, a supply of data pro- cessing software (Hydrom) designed by the Office pour la Recherche Scientifique et Technique d'Outre Mer (Office for Overseas Scientific and Technical Research; ORSTOM), and training of hydrology technicians. Financed by the United Nations Development Programme (UNDP), the European Economic Community, and the Organization of Petroleum Exporting Countries, the project is managed by the World Meteorological Organization (WMO). Currently, only 15 stations are operational. The World Health Organization­Onchocerciasis Control Programme in West Africa (WHO-Oncho) program was one of the first users of this technology in the region; data collection platforms were installed in the northern part of Côte d'Ivoire, in southern Mali, and in Guinea, among others, along with the Argos direct reception stations in the offices of the WHO-Oncho program in Bobo-Dioulasso, Bamako, and Odienne. The primary hydrology research work on the Niger River to the Nigerian border is the ORSTOM Hydrological Monograph No. 8 in two volumes, published in 1986 under the direction of Y. Brunet-Moret, with the assis- tance of P. Chaperon, J. P. Lamagat, and M. Molinier. The monograph covers data up to 1979. For Benin, Chad, and Cameroon, ORSTOM monographs were also used (Olivry 1986; Le Barbe 1990). For Nigeria, information has been gathered from various sources; a comprehensive overview is not cur- rently available. In 1992, for West and Central Africa, country reports were published cov- ering the management of hydroclimatic data collection and databases by agencies for meteorology, groundwater, and hydrology. This 23-volume Water Assessment Project was a significant and informative undertaking, despite some gaps in coverage and quality. Meteorological data from synoptic observation stations are generally very well monitored.11 Rainfall stations are well maintained, although dissemination of information could be improved, specifically in providing farmers with relevant meteorological information in a timely manner. Hydrologic data on water levels are gen- erally insufficient. Limnimetric stations need to be standardized with gauges to measure hydrologic parameters. The national water departments are responsible for hydrometric network maintenance, for which they often receive financing from bilateral cooperation agencies. Generally, the prac- tice is to attain the standards set by the "Operational Hydrology Practices" of the WMO in terms of network density, although these may not be the best adapted to the countries of Sub-Saharan Africa. 128 THE NIGER RIVER BASIN: A VISION FOR SUSTAINABLE MANAGEMENT In 1993, the WMO promoted a global observation system for the hydro- logical cycle (World Hydrological Cycle Observing System; WHYCOS), using monitoring reference stations (hydrological observatories) with real time or near real time data transmission (Rodda and others 1993). The pilot Afrique de l'Ouest et Centrale (West and Central Africa)­Hydrological Cycle Observing System (AOC-HYCOS) project was launched in 1996 in Ouagadougou, Burkina Faso, with French funding and was renewed in January 2000. The focus of this project was to allow national hydrological departments to post and share observations on a central Web site created by the Ecole Inter-Etats d'Ingénieurs de l'Equipement Rural (Interstate Institute for Rural Engineering) in Ouagadougou. Subsequently, the project was headquartered in Niamey, Niger, at the NBA's Centre Inter-Etats de Prévision (Interstate Forecasting Center; CIP), in association with the Centre Régional de Formation et d'Application de la Météorologie et de l'Hydrologie Opérationnelle (Regional Center for Training and Application of Meteorology and Operational Hydrology; AGRHYMET).12 There are other national or subregional monitoring activities in the Basin. The Gestion hydro-écologique du Niger supérieur Mali-Guinée (GHENIS) project (financed by the Netherlands) supports data collection platforms and remote satellite transmission, including hydrometric sensors and water quality measurement sensors (for example, conductivity, turbidity, and tem- perature) in the Upper Niger River Basin (Mali and Guinea) from Bamako. In Nigeria, the National Water Resources Master Plan lays out hydrological areas (HA). For the Niger River Basin, there are the Northwest Region HA- I, the Central West Region HA-II, the Central East Regions HA-III/IV, and the South East Regions HA-V/VII, in which various river basin develop- ment authorities manage most of the water measuring stations. The Federal Department for Navigable Waterways manages its own stations and the National Electric Power Authority manages dam sites. In Cameroon, hydrol- ogists from the Institut de Recherches Géologiques et Minières (Institute for Geological and Mining Research) in charge of a national network no longer have access to data collected by the National Electricity Company, which manages its own network since it was privatized. Other methods also exist, including user-friendly on-site data transmission by satellite from manual test units. This system is already in use for meteorology and by the United Nations Food and Agriculture Organization in village markets to determine daily commodity prices. There is other progress in hydrology, such as flow measurement by the Acoustic Doppler Current Profiler, which is a simple exploration of sections through a Doppler monitoring radar (for example, small sections of a shallow river). APPENDIXES 129 Appendix 4: Glossary Acacia Genus Robinia, any of various spiny trees or shrubs of the genus Acacia, similar to the locust. Average annual The annual ratio between TSS flow and water flow, concentrations and the rate of specific transport (Ts). Base flow The normal sustained low flow of the river, originat- ing entirely from groundwater discharging to the river. Boreal Of or relating to the north; northern, of or concerning the north wind. Bourgou grass Echinochloa stagnina. A tropical aquatic perennial growing along rivers and in lakes and lagoons in water up to 3 meters deep, the stems of which root at the nodes, and produce excellent regrowth for grazing during the dry season. Continental Terminus Composed of claylike sandstone, sand, and clays. A continuous stratum aquifer with good water quality located within the Niger Basin. Endoreism A water body that remains isolated and cut off with- out any geomorphic means to connect to the water network. Erg Also called "Sand Sea." In a desert region, area of large accumulation of sand. Ferralitic and Relating to or containing iron, characterized by high ferruginous soils sand content. Fouta Djallon The mountainous massif known as the West African headwaters. Guinée Forestière Includes the southern high plateaus of the Fouta Djallon Massif. Harmattan A dusty and hot wind from the Sahara that blows toward the western coast of Africa during the winter (December­May). Haute Guinée Includes the northern and eastern highlands of the Fouta Djallon Massif. Hydrography Refers to water and drainage features and descrip- tion of physical properties of the waters of a region. Hydromorphic soils Characterized by the temporary or permanent presence of a surface water table. Interannual flow Average yearly flows for a period of years. Isohumic soils Sahelian soils poor in organic matter with a deep homogenous sandy profile. Isohyets Relating to or indicating equal rainfall. 130 THE NIGER RIVER BASIN: A VISION FOR SUSTAINABLE MANAGEMENT Lateritic butte A steep-sided, flat-topped hill formed by erosion of flat laying strata, where remnants of a resistant layer (in this case, lateritic soil, see below) protect the softer rocks underneath. Lateritic soils A red residual soil in humid tropical and subtropical regions that is leached of soluble minerals, aluminum hydroxides, and silica, but that still contains concen- trations of iron oxides and iron hydroxides. Hardens on exposure to the atmosphere. Limnologic stations Monitoring stations for gathering physical, chemical, meteorological, and biological data on the conditions in fresh waters. Lithosol A type of azonal soil having no clear expression of soil morphology consisting of freshly and imperfectly weathered mass. Monsoon A humid and wet wind blowing from the southwest in the summer (June­November) and responsible for the rainy season in West Africa. Niger Bend Refers to the major change in the Niger River flow direction from south-southwest to east-southeast, downstream from the Inland Delta in Mali, upstream from the city of Gao. Office du Niger Refers to the large irrigation area in Mali, and the Malian government agency, which manages the irri- gation schemes. Reach An extended portion of a waterway. Synoptic stations Monitoring stations that gather meteorological data over large areas at a specified instant in time, for the purpose of projecting the data into the future, that is, to give weather forecasts. TDS Total dissolved solids. The standard measure of minerals dissolved in water. Used to evaluate water quality. TSS Total suspended solids. The total of all settleable and nonsettleable solids in a sample of wastewater, mea- sured in milligrams per liter. Tussocky grass Sporobolus indicus. A compact tuft especially of grass or sedge; also an area of raised solid ground in a marsh or bog that is bound together by roots of low vegetation. Vertisol Tropical brown soil or tropical black clay characterized by at least 30 percent clay. Wadi A desert watercourse that is usually dry and contains water only occasionally, after heavy rainfall. Endnotes 1. Benin, Burkina Faso, Cameroon, Chad, Côte d'Ivoire, Guinea, Mali, Niger, and Nigeria. 2. Based on 2002 gross national income (GNI) per capita (World Bank 2004b). 3. The HDI ranges from 1 to 177, with the latter being the lowest. Eight of the nine Basin countries fall into the "Low Human Development Category," ranked at 142 and below (UNDP 2004). 4. In the era when Bismarck was the arbiter of Europe and Germany wanted to create "its" colonies, sections of Africa were defined for each colonial power: Cameroon for Germany, Nigeria for Great Britian, and Nigerian Sudan and Oubangui-Chari for France. 5. This includes projects that involve or have impacts on navigation, agricul- ture, hydropower, industry, water quality, and flora and fauna. 6. For example, HYDRONIGER, directed by the World Meteorological Organi- zation (WMO), had been financed by a number of donor institutions and bilaterals. 7. This commitment was further reinforced by a cooperative framework confirmed by the attending donors to support this process. 8. Nigeria extends across four climatic zones: semiarid, tropical pure, transi- tional tropical, and equatorial in the Lower Niger Delta. 9. For further discussion of benefits, see Sadoff and Grey (2002). 10. The principle of subsidiarity is regularly used in the European Union context, and suggests that implementation of a particular policy is delegated to the lowest appropriate level. 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Index Bani Watershed international partners in, 69 hydrography, 13­14 key ingredients for success of, hydrology, 34­36 68­69 map, 72m moving from unilateral TDS, 53­54, 55f, 124f development to, 59­60, 69 TSS, 48­50, 49f, 50t, 55f, 125f SDAP (Sustainable Development Benin, 2­3t, 4, 46­48, 47t Action Program), xiv, 10, 61, Benue River and Basin 63­64, 69 hydrography, 17­18 Shared Vision process, xiv, 10, hydrology, 44­45 61, 63­64, 69 map, 76m sociological factors, 65­67 TSS, 52, 53f types of cooperation, Burkina Faso, 2­3t, 4, 46­48, 47t 64, 65f Côte d'Ivoire, 2­3t, 5, 46­48, 47t Cameroon, 2­3t, 4­5, 46­48, 47t Chad, 2­3t, 5, 46­48, 47t data management, 65, 84m, civil war and conflict, effects of, 127­128 66 debt sustainability, 65 climate, 25­29, 25t, 26f, 28f, 29f, definitions, 129­130 86t, 90f degradation, environmental colonial era, Niger River basin reasons for, 66­67 during, 8 water quality, 56­57 cooperative development of Niger Delta. See Inland Delta; Lower River basin, xiii­xiv, 58­69 Niger and Delta data for decision-making, 65, development aims. See cooperative 84m, 127­128 development of Niger River dynamic approach, need basin for, 60 dissolved solids, total (TDS), environmental factors, 66­67 53­56, 55f, 56t, 124f, 126f, 130 factors involved in, 63­67 goals of, 58­59 environment and ecology, 24, historical background, 7­10 66­67. See also physical institutional and legal characteristics of Niger River foundations, 60­62 basin 141 142 INDEX environmental degradation monitoring system, 65, 84m, reasons for, 66­67 127­128 water quality, 56­57 parameters, 35t, 91t, 93t evaporation rates, 37­41, 38f, 39f, rainfall, 27­29, 28f, 29f, 81­83m, 39t, 40f, 83m, 87t.89f 88f, 92t runoff, 28, 29f flooding Upper Basin, 32­36, 33t, 35t in Inland Delta and Lakes HYDRONIGER monitoring District, 41­42f system, 65, 84m, 127­128 in Middle Niger, 43f in Upper Basin, 35­36, 35t infrastructure sharing, 64­65 flow rates, 33t, 37t, 40f, 47t, 49t, Inland Delta and Lakes District 51t, 94­123t evaporation in, 37­41, 38f, 39f, FONDAS (Niger River Basin 39t, 40f Development Fund), 9 flooding in, 41­42f hydrogeology, 21 geography. See physical hydrography, 14­15 characteristics of Niger hydrology, 36­42, 37t, 38f, 39f, River basis 39t, 40­42f geology and hydrogeology, 20­22 map, 73m, 85m glossary, 129­130 TDS, 54, 55f Guinea, 2­3t, 5­6, 33t, 46­48, 47t TSS, 50­52, 51t international partners in Heads of State Summit, xiv, 10, 61, cooperative development, 69 63, 68 ionic composition, 54, 56t, 126f humidity, 89f, 90f isohyets, 27, 28f, 81­82m, 129 hydrogeology, 20­22 hydrography, 12­19 Lakes District. See Inland Delta hydrology, 30­48 and Lakes District Bani Watershed, 34­36 legal framework for cooperative Benue River and Basin, 44­45 development, 62 country-specific features, Lower Niger and Delta 46­48, 47t hydrogeology, 21­22 evaporation rates, 37­41, 38f, hydrography, 18­19, 31f 39f, 39t, 40f, 83m, 87t.89f hydrology, 45­46 flow rates, 33t, 37t, 40f, 47t, 49t, map, 77m 51t, 94­123t TDS, 54­56, 56t humidity, 89f, 90f TSS, 52, 53f Inland Delta and Lakes District, 36­42, 37t, 38f, 39f, 39t, Mali, 2­3t, 6, 46­48, 47t 40­42f maps, 71­85m Lower Niger and Delta, 45­46 master plans, limitations of, 60 maps, 71­85m Middle Niger Middle Niger, 42­44, 43f climate, 86t INDEX 143 hydrography, 15­17 potential roles of, 67 hydrology, 42­44, 43f renewal of, 69 maps, 74­75m Niger River Basin Development TDS, 54­56, 56t Fund (FONDAS), 9 TSS, 52, 53f, 54t Nigeria, 2­3t, 7, 46­48, 47t migration flows, effect of, 66 monitoring system, 65, 84m, OMVS (Senegal River Basin 127­128 Organization), 64 natural environment, 24, 66­67. See physical characteristics of Niger also physical characteristics of River basin, xi­xii, 1, 11­29 Niger River basin climate, 25­29, 25t, 26f, 28f, 29f, navigation 86t, 90f map of navigable segments, flow rates, 33t, 37t, 40f, 47t, 49t, 80m 51t, 94­123t physical characteristics of general physical environment, navigable segments, 19­20 1, 11­12 TSS affecting, 52­53 geology and hydrogeology, NBA. See Niger River Basin 20­22 Authority hydrography, 12­19 Niger, 2­3t, 6­7, 46­48, 47t hydrology (See hydrology) Niger Basin Convention of 1980, maps, 71­85m 9, 60 natural environment and Niger Delta. See Inland Delta; ecosystem, 24 Lower Niger and Delta navigable segments, 19­20 Niger River basin, vii­viii, x­xi, 1 rainfall, 27­29, 28f, 29f, 81­83m, cooperative development 88f, 92t (See cooperative development runoff, 28, 29f of Niger River basin) soil types, 22­23, 23f, 129­130 countries of, 1­7, 2­3t poverty reduction as aim of history of, 7­10 cooperative development, maps, 71­85m 58­59 origins of name, 1 physical characteristics quality of water, 56­57 (See physical characteristics of Niger River basin) rainfall, 27­29, 28f, 29f, 81­83m, Niger River Basin Authority 88f, 92t. See also hydrology (NBA), xiii­xiv runoff, 28, 29f audit of, 63 historical background and SDAP (Sustainable Development establishment of, 9­10 Action Program), xiv, 61, institutional foundation for 63­64, 69 cooperative development and, Senegal River Basin Organization 60­61 (OMVS), 64 144 INDEX Shared Vision process, xiv, 10, 61, Upper Basin. See also Bani 63­64, 69 Watershed socioeconomic characteristics of climate, 86t Niger River basin countries, flooding in, 35­36, 35t 23­24t hydrogeology, 20­21 sociological factors in cooperative hydrography, 12­14 development, 65­67 hydrology, 32­36, 33t, 35t soil types, 22­23, 23f, 129­130 map, 72m solids seasonal variability in, 34­35 total dissolved (TDS), 53­56, 55f, TDS, 53­54, 55f 56t, 124f, 126f, 130 TSS, 48­50, 49f, 50t, 55f total suspended (TSS), 48­53, 49f, 50­51t, 53f, 54t, 125f, 130 war and conflict, effects of, 66 subsidiarity, xiv, 67, 131n10 water resources, xii­xiii, subsidiary agreements, need for, 62 30­57 suspended solids, total (TSS), hydrogeology, 20­22 48­53, 49f, 50­51t, 53f, 54t, hydrography, 12­19 125f, 130 hydrology (See hydrology) Sustainable Development Action quality of water, 56­57 Program (SDAP), xiv, 61, rainfall, 27­29, 28f, 29f, 81­83m, 63­64, 69 88f, 92t runoff, 28, 29f temperature, seasonal variations TDS, 53­56, 55f, 56t, 124f, in, 90f. See also climate 126f, 130 total dissolved solids (TDS), 53­56, TSS, 48­53, 49f, 50­51t, 53f, 54t, 55f, 56t, 124f, 126f, 130 125f, 130 total suspended solids (TSS), World Bank as international 48­53, 49f, 50­51t, 53f, 54t, partner in cooperative 125f, 130 development, 69 Eco-Audit Environmental Benefits Statement The World Bank is committed to preserving endangered forests and natural resources. We have chosen to print The Niger River Basin: A Vision for Sustainable Management on 30% post-consumer recycled fiber paper,processed chlorine free. The World Bank has formally agreed to follow the recommended standards for paper usage set by the Green Press Initiative--a nonprofit program supporting publishers in using fiber that is not sourced from endangered forests. For more information, visit www.greenpressinitiative.org. In 2005, the printing of these books on recycled paper saved the following: Trees* Solid Waste Water Net Greenhouse Gases Electricity 20 330 2,991 648 1,202 *40' in height and Pounds Gallons Pounds KWH 6-8" in diameter The Niger River Basin, home to 100 million people, is a vital yet complex asset of West and Central Africa. Traversing nine countries--Benin, Burkina Faso, Cameroon, Chad, Côte d'Ivoire, Guinea, Mali, Niger, and Nigeria--the Niger River embodies these nations' livelihood and geopolitics. The Niger is an origin of identity, a route for migration and commerce, a source of conflict, and a catalyst for cooperation. Cooperation among decisionmakers and users is crucial to address the threats to water resources. The Niger River Basin Authority (NBA) is mandated to foster this cooperation and sharing of resources. Through an improved framework and a Shared Vision process, the NBA is fostering a renewed commitment to sustainable management and development of the Basin's resources. The Niger River Basin: A Vision for Sustainable Management discusses the geology, hydrology, climate, water quality, and water use of the Niger River Basin and provides a suggested approach for sustainable development of the Basin's water resources. It attempts to capture the full spectrum of the Niger ecosystem's values and benefits and supports the integration of science and decisionmaking to serve as a tool for transboundary cooperative environmental and water resources management. ISBN 0-8213-6203-8