103629 THE ZIMBABWE WATER FORUM August 2014 POLICY NOTE 11 Page 1 The Zimbabwe Water Forum provides a platform for Government and Development Partners to share international best practices in the water sector between Zimbabwe and other countries. The forum was formed through a partnership between the Ministry of Environment, Water and Climate, the Multi-Donor Trust Fund and the World Bank and is hosted by the World Bank’s Zimbabwe Country Office and the Urban WSS Thematic Group. Climate Change and Water Resources Planning, Development, and Management in Zimbabwe This policy note summarizes the issues paper on Climate Change and Water Resources Planning, Development and Management prepared at the request of the Ministry of Environment, Water, and Climate of Zimbabwe. The issues paper was intended to help highlight the potential impacts of climate change on the hydrological cycle and to strengthen the water-related aspects of the National Climate Change Response Strategy (NCCRS). Rafik Hirji, World Bank, provided the overall technical leadership and coordinated consultant inputs for its preparation with support from the Analytical Multi Donor Trust Fund (AMD TF) under the Flexible Technical Assistance for the Water Sector in Zimbabwe managed by Michael Webster of the World Bank office in Harare. The paper’s principal authors are Richard Davis (Senior Water Resources consultant) and Rafik Hirji (Senior Water Resources Specialist). Consultant inputs were provided by Professor Amon Murwira and Dr. Richard Owen of the University of Zimbabwe and Mr. Zebediah Murugnweni, a senior water resources expert in Harare. Water, Climate, and the Economy The climate in Zimbabwe is highly variable both spatially and temporally. Mean annual Zimbabwe has embarked on a long-term process precipitation (MAP) is 657 millimeters; there is a of rebuilding its economy following a period of distinct precipitation gradient from the drier economic decline and breakdown of social south to the wetter north of the country. The wet services during the 2000s. Clean water, the safe season usually extends from October to April, disposal of sewage, irrigation, and hydropower with most rain falling between December and are among the services in urgent need of February. Rainfall varies considerably from year to rehabilitation and expansion. One challenge that year, particularly in the northern plateau where has yet to be factored into the recovery plans is inter-annual precipitation can vary by almost 50 the effect of climate change on the country’s percent. Zimbabweans can expect drought to water resources and its implications for planning, occur between one and three years every decade. design, and management of these resources. The nation is also prone to floods driven by cyclones. Some 80 percent of Zimbabweans are Water is central to the economy of Zimbabwe and farmers or are engaged in agro-industry, and the to its people’s livelihoods and wellbeing, but the economic damage and human suffering caused by availability and reliability of water resources are extreme weather events can be very high; impacts dependent on highly variable climatic conditions. include water and food shortages, the spread of Climate change has already had an impact on disease, economic losses to farmers, and the water resources in Zimbabwe, and the effects are destruction of infrastructure. projected to become more severe over the next century. THE ZIMBABWE WATER FORUM August 2014 POLICY NOTE 11 Page 2 Distribution of precipitation across Zimbabwe Average Seasonal Precipitation (mm) 1901–2010 While precipitation is the main factor influencing develop projections for rainfall, runoff, and the availability of water resources, rates of runoff recharge. and groundwater recharge can have a more direct Under both scenarios, MAP is projected to effect on livelihoods. More than 70 percent of the decrease significantly by 2050 and 2080 in all population of Zimbabwe relies on wells and bore- catchments, except for Manyame where it could holes for their drinking water, yet there have been increase slightly under the ecologically aware few studies of rates of recharge or depletion of scenario. The most affected catchments are in the these resources. Surface water plays a critical role south of Zimbabwe—Mzingwane and Runde in urban and rural water supply as well as for catchments—where MAP could decline by 12 to irrigation and electricity production, but there is 16 percent by 2050 and by 12 to 25 percent by considerable uncertainty about the current state 2080. Precipitation is likely to remain relatively of Zimbabwe’s surface water resources and their constant in the northwest of the country use. Mean Annual Runoff (MAR) is dependent on (Manyame and Mazowe catchments). MAP could precipitation, but other factors such as silting, stabilize or start to recover in the more affected land clearance, and recharge and infiltration rates catchments—Gwayi, Mzingwane, Runde, Sanyati can also affect runoff, making it particularly and Save—between 2050 and 2080 under the sensitive to environmental change. ecologically aware scenario, although it would Climate change will affect water resources continue to decline in almost all catchments if population growth and technology continue at the This study used limited modeling (using the CSIRO current rates. Mk3 global circulation model and the A2a and B2a scenarios) to examine the potential impacts of The uncertainties in the assumptions used in climate change on precipitation and runoff in these models mean that the projected changes to Zimbabwe’s seven catchments. A2a is a business- precipitation may vary in scale, but the overall as-usual scenario that assumes high population pattern of a decrease in MAP across western and growth, increased energy use, conservative southern Zimbabwe to 2050—with continuing technologies, and significant land use changes. precipitation declines to 2080 if emissions of B2a is an ecologically aware scenario that assumes greenhouse gases are not curbed—should be that local solutions are sought for environmental regarded as a reliable conclusion. In spite of the challenges, population grows more slowly, overall declines in precipitation, greater climate technology adapts to new conditions, and changes variability is expected to create higher risks of to land use are more gradual. The years 2050 and extreme climate events including drought and 2080 (consistent with the NCCRS) were used to flood. THE ZIMBABWE WATER FORUM August 2014 POLICY NOTE 11 Page 3 Estimated current, 2050, and 2080 MAP (mm) by catchment Catchment Current 2050 2050 2080 2080 Business as usual Ecologically aware Business as usual Ecologically aware scenario scenario scenario scenario Observed World Climate Data (A2a) (B2a) (A2a) (B2a) Gwayi 599 605 545 (10%) 576 (5%) 515 (15%) 587 (3%) Manyame 709 785 769 (2%) 795 (-1%) 757 (4%) 800 (-2%) Mazowe 824 915 854 (7%) 907 (1%) 864 (6%) 899 (2%) Mzingwane 547 506 430 (15%) 447 (12%) 379 (25%) 445 (12%) Runde 606 706 592 (16%) 622 (12%) 534 (24%) 616 (13%) Sanyati 635 738 684 (7%) 716 (3%) 655 (11%) 723 (2%) Save 815 915 784 (14%) 839 (8%) 756 (17%) 832 (9%) Note: Percentage decreases in MAP are shown in brackets. A negative percentage indicates an increase in rainfall. The Mean Annual Runoff (MAR) was calculated Mzingwane catchments could decline significantly using the MAR and MAP relationships developed if greenhouse emissions are not controlled. Even by ZINWA for all catchments. As was found in more dramatically, a 3–7 percent decline in other climate studies, there is a proportionately precipitation in Sanyati catchment by 2050 will greater decline in runoff due to climate change result in a 10–23 percent decline in runoff. Given than in precipitation in all Zimbabwe. This the simplicity of the method, there is considerable multiplier effect on runoff means that even small uncertainty about the extent of the decreases in declines in MAP can have significant impacts on river flow, but the general prediction of a drier water availability. For example, Manyame climate with considerably less river flow across catchment is projected to face only a 4 percent southern and western Zimbabwe and much decrease in precipitation by 2080 under business smaller impacts in Manyame and parts of Mazowe as usual, but this could result in a 10 percent catchments, is a reliable conclusion. decline in MAR. But river flows in Gwayi and Estimated current, 2050, and 2080 MAR (Gl) by catchment Catchment Current 2050 2050 2080 2080 (World Climate Business as usual Ecologically aware Business as usual Ecologically aware data) scenario scenario scenario scenario (A2a) (B2a) (A2a) (B2a) Gwayi 2,088 - 1,047 (50%) - 1,432 (31%) Manyame 4,496 4,244 (6%) 4,661 (-4%) 4,046 (10%) 4,736 (-5%) Mazowe 5,665 4,825 (15%) 5,559 (2%) 4,974 (12%) 5,443 (4%) Mzingwane 1,082 - 379 (65%) - 356 (67%) Runde 3,530 1,967 (44%) 2,343 (33%) 1,311 (63%) 2,271 (36%) Sanyati 6,905 5,314 (23%) 6,248 (10%) 4,483 (35%) 6,471 (6%) Save 8,010 5,455 (32%) 6,558 (18%) 4,970 (38%) 6,414 (20%) Note: Percentage decreases in MAR are shown in brackets. A negative percentage means runoff is predicted to increase. Groundwater recharge rates as well as the impact recharge from rain are the most susceptible to the of climate change on recharge rates were effects of drought as well as the most subject to estimated using expert knowledge rather than the increased evapotranspiration expected with field measurements for each catchment. Overall, the higher temperatures projected under climate decreases in precipitation will lead to change. These types of aquifers are concentrated proportionate decreases in groundwater in the western regions of Zimbabwe, and farmers recharge, but this effect is likely to be different in there who depend on groundwater for irrigation the geologically different aquifers in Zimbabwe. and drinking water could face declines in yields or Unconfined, shallow aquifers that receive direct even crop failure. In addition, reduced THE ZIMBABWE WATER FORUM August 2014 POLICY NOTE 11 Page 4 precipitation and runoff are expected to increase 25 percent (Mzingwane) by 2080. A recent people’s dependence on groundwater, regional study estimates that the percentage of exacerbating groundwater depletion. population at very high risk of groundwater drought in Zimbabwe could rise from 32 percent Reductions in groundwater recharge are expected to 86 percent without measures to adapt to the to range from 2 percent (Manyame) to 16 percent effects of climate change. (Runde) by 2050 and to 4 percent (Manyame) to Estimated groundwater recharge (Gl/yr) by catchment Catchment Recharge as % Current 2050 2050 2080 2080 MAP Business as usual Ecologically aware Business as usual Ecologically scenario scenario scenario aware scenario (A2a) (B2a) (A2a) (B2a) Gwayi 3% 1596 1438 (10%) 1520 (5%) 1359 (15%) 1549 (3%) Manyame 6% 1907 1868 (2%) 1932 (-1%) 1839 (4%) 1944 (-2%) Mazowe 6% 1918 1791 (7%) 1901 (1%) 1811 (6%) 1844 (2%) Mzingwane 2% 632 537 (15%) 558 (12%) 473 (25%) 556 (12%) Runde 5% 1449 1215 (16%) 1277 (12%) 1096 (24%) 1265 (13%) Sanyati 5% 2750 2549 (7%) 2668 (3%) 2441 (11%) 2694 (2%) Save 6% 2660 2279 (14%) 2439 (8%) 2197 (17%) 2418 (9%) Note: Percentage decreases in recharge are shown in brackets. A negative percentage means that recharge is predicted to increase. Climate change will profoundly impact change could have a dire impact on the Zimbabwe’s economy livelihoods of these farmers, particularly in the south and west of the country. In addition, the This preliminary modeling suggests that climate manufacturing sector relies heavily on agricultural change could have major impacts on Zimbabwe's produce, so that the ripple effect of scarce water resources. Water supply to urban and rural resources and higher prices could be significant. areas in the south and west of the country could The projected reductions in runoff could also be seriously affected, and reductions in decrease the efficiency of the country’s groundwater could undermine the livelihoods of hydropower plants, which currently provide over rural communities. 80 percent of Zimbabwe’s electricity. When the reduction in runoff and groundwater Reduced precipitation and increased evaporation recharge expected under climate change is in southern and western parts of Zimbabwe, as coupled with projected high rates of population well as more frequent droughts and floods, will growth, the amount of water available per person make it more difficult to manage the country’s could decrease to critical levels. Even with water resources. Existing dams built for water relatively low population growth, national per supply and irrigation may become less reliable, capita water availability is projected to decline by and new infrastructure will need to be designed 38 percent; medium or high population growth to be more resistant to extreme climate events. scenarios could move Zimbabwe from the UN’s Reduced precipitation and runoff will likely lead to “water stress” to the “absolute water scarcity” increased reliance on groundwater because it is category. shielded from evaporative losses and better buffered against increased climate variability than The impacts of the reduced precipitation and surface water, but currently most water increased temperatures expected under climate management plans in Zimbabwe do not include change on the economy of Zimbabwe could be groundwater. severe, particularly in the agricultural and energy sectors. Although agriculture contributes only 14 percent of GDP, it employs 60 to 70 percent of the population; reductions in yields from climate THE ZIMBABWE WATER FORUM August 2014 POLICY NOTE 11 Page 5 Adaptation should be coordinated across action. Local responses will be critical; catchment sectors councils are the most efficient way to ensure that Anticipating the potential effects of climate local needs are met and local knowledge is change should become a normal part of exploited, but ZINWA will need to support these operational thinking in water management and efforts by helping councils revise and update River planning. There are many opportunities for the System Outline Plans to meet the challenges of water sector to adapt to climate change. climate change. Adaptation in advance of climate change will All the proposed measures to adapt to climate allow water to be captured and used more change are no-regrets options: wiser water use, efficiently in the face of declining availability, and increased information gathering and will encourage managers and water users to dissemination, and improved coordination in respond flexibly to increased variability. water management will serve Zimbabwe well no Management will need to address both supply matter what the future holds. The reality of and demand: the amount of available water can climate change increases the urgency to take be increased through reuse of wastewater, action now. rainwater harvesting, controlling pollution, and Recommendations reducing unaccounted for water in supply systems while the amount of water used can be decreased This study illustrates the need for better scientific through rational pricing and revised water information if Zimbabwe is to develop a allocation systems. Plans for the rehabilitation comprehensive strategy for climate change and expansion of Zimbabwe’s water infrastructure adaptation in the water sector. This includes: will also need to include the effects of climate better data on climate and water resources change, and the design standards for dams, gathered through comprehensive monitoring bridges, and levees should be reassessed to programs; better understanding of groundwater withstand increased flooding. The destructive resources and use; predictive models of surface force of floods could also be reduced by better and groundwater systems; accurate assessment of protection and management of floodplains and current and future uses of water; and a more wetlands to absorb floodwaters. comprehensive exercise to model the potential impact of climate change on water resources than In order to adapt efficiently, it will be important to was possible here. This study recommends the collect better information about the effects of development of a comprehensive Climate Change climate change on the country’s water resources Adaptation Strategy for the water sector based on and to communicate that information to better information and modeling in order to communities and administrators. Surface water implement some of the adaptation opportunities monitoring has deteriorated sharply over the past identified in this report. 20 years, and groundwater monitoring is virtually nonexistent. Without a better understanding of The formation of the Ministry of Environment, current resources, it will be impossible to Water, and Climate, which merges the mandates accurately project and plan for the future. of the three key areas—environment, water, and climate—under the new cabinet, provides an Adapting to climate change will require excellent opportunity to re-align and work out coordination between water managers at every effective coordination at the policy, regulatory, level of government. Currently the management and institutional levels to systematically address of water resources spans the responsibility of a climate change adaptation in the water and number of ministries. Various policy instruments water-related sectors. (for example, the NWP and the Environmental Management Act) promote coordination, but it has been difficult to translate these principles into THE ZIMBABWE WATER FORUM August 2014 POLICY NOTE 11 Page 6 The Zimbabwe Water Forum Policy Notes Series Between 2011 and 2014, at the request of the Government of Zimbabwe, through the Ministry of Water Resources Development and Management, and with support from the Zimbabwe Analytical Multi-Donor Trust Fund, the World Bank has undertaken a series of analytical studies and technical assistance in the water and sanitation sector. These studies are captured in the Zimbabwe Water Forum Policy Note Series. The task team leader for the studies is Michael Webster, Sr. Water and Sanitation Specialist in Harare (mwebster@worldbank.org) with support from Priscilla Mutikani (pmutikani@worldbank.org). All notes have been edited by Rolfe Eberhard and Hilary Gopnik.  Policy Note 1: A 24/7 water supply is possible for Harare and other cities: Lessons on what it takes from water manager Neil Macleod  Policy Note 2: Modeling the water sector in South Africa and Zambia  Policy Note 3: Zimbabwe’s new National Water Policy: Responding to Cha llenges to Create a Foundation for Sustainable Growth  Policy Note 4: The Future of Sanitation in Harare and Other Cities: Perspectives on Possible Pathways to Recovery  Policy Note 5: The Beitbridge Emergency Water Supply and Sanitation Project: Lessons Learnt  Policy Note 6: Zimbabwe Urban Water Tariff Study  Policy Note 7: Improving the operations of Harare’s water and wastewater treatment plants  Policy Note 8: Zimbabwe Dam Safety Study  Policy Note 9: Zimbabwe Infrastructure Policy Review  Policy Note 10: Enhancing Water and Sanitation Services through Performance Contracts: Lessons from Africa  Policy Note 11: Climate Change and Water Resources Planning, Development, and Management in Zimbabwe