67845 The Cost of Adapting to Extreme Weather Events in a Changing Climate BANGLADESH Development Series Paper No. 28 THE WORLD BANK December, 2011 World Bank Office Dhaka Plot - E-32 , Agargaon, Sher-e-Bangla Nagar, Dhaka- 1207, Bangladesh Tel: 880-2-8159001-28 Fax: 880-2-8159029-30 www.worldbank.org.bd World Bank 1818 H Street, N.W. Washington DC 20433, USA Tel: 1-202-4731000 Fax: 1-202-477-66391 www.worldbank.org All Bangladesh Development Series (BDS) publications are downloadable at: www.worldbank.org.bd/bds Standard Disclaimer: This volume is a product of the staff of the International Bank for Reconstruction and Development/ The World Bank. 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. The boundaries, colors, denominations and other information shown on any map in this work do not imply any judgment on the part of the World Bank concerning the legal status of any territory or the endorsement or acceptance of such boundaries. Copyright Statement: The material in this publication is copyrighted. The World Bank encourages dissemination of this work and will normally grant permission to reproduce portion of the work promptly. Map Credits: The maps published in this report were produced by the Institute of Water Modeling (IWM) (Figs. 2.1, 2.2, 4.1, 4.3, 5.1 and Box 1.2) and the Center for Environmental and Geographic Information Services (CEGIS) (Fig 5.2). Cover Photo: Quddus Alam/DrikNEWS/Majority World Back Cover Photo: Palash Khan/Drik/Majority World Design & Print: Progressive Printers Pvt. Ltd. Foreword Global warming is expected to have severe consequences for developing countries prone to extreme weather events. Projections by the Intergovernmental Panel on Climate Change and the World Meteorological Organization suggest an increase in the frequencies and/or intensities of climate extremes in the 21st century. Some recent examples illustrate how severe the consequences of such extreme weather events can be: heavy floods in Australia and Brazil in 2011; extreme winter weather throughout Europe in 2010; Russia's heat wave in 2010; devastating floods in Pakistan, India, China, and Mozambique in 2010; and super cyclones in Myanmar in 2008 and Bangladesh in 2007. Adaptation to increased risks of severe weather events, as well as other impacts of climate change, is essential for development. Adaptation will require climate-smart policies and investments to make countries more resilient to the effects of climate change, including losses of property, habitat, infrastructure, and lives. Country governments and their citizens, as well as development partner institutions and climate negotiators, need a better understanding of the potential damage due to climate change and adaptation costs to formulate effective adaptation to extreme weather events. To shed light on potential damage from extreme weather events and adaptation costs, World Bank staff and experts from the Institute of Water Modeling and the Center for Environmental and Geographic Information Services in Bangladesh have conducted a study on the potential intensification of inland monsoon floods and cyclones for Bangladesh in a changing climate. This study is timely and of prime importance as it identifies vulnerable populations and infrastructure, quantifies outstanding deficits in dealing with current climate-related risks, and estimates the cost of adaptation to avoid further damage due to climate change. John Henry Stein Ellen Goldstein Sector Director Country Director Sustainable Development Bangladesh South Asia v Acknowledgments This report was prepared by a team consisting of Maria Sarraf (Task Team Leader), Susmita Dasgupta (Lead Environment Economist), and Norma Adams (Editor). The team would like to thank Naomi Ahmad, Faria Selim, Luis Andres, Ainun Nishat, Mehrin A. Mahbub, Khawaja Minnatullah, and Sayeeda Salim Tauhid for their valuable input. The report combines the results of two studies: Vulnerability of Bangladesh to Cyclones in a Changing Climate, prepared by Susmita Dasgupta, Mainul Huq, Zahirul Huq Khan, Manjur Murshed Zahid Ahmed, Nandan Mukherjee, Malik Fida Khan, and Kiran Pandey; and Climate Proofing Infrastructure in Bangladesh, prepared by Susmita Dasgupta, Mainul Huq, Zahirul Huq Khan, Md. Sohel Masud, Manjur Murshed Zahid Ahmed, Nandan Mukherjee, and Kiran Pandy. Both studies were prepared under the World Bank- supported Economics of Adaptation to Climate Change Program. The team would like to acknowledge the financial support provided by the Bangladesh Climate Change Resilient Fund (BCCRF), funded by the Department of International Development of the United Kingdom, the Embassy of Denmark in Bangladesh, the European Commission, the Swedish International Development Cooperation Agency, and the Swiss Agency for Development and Cooperation. Abbreviations and Acronyms BCCSAP Bangladesh Climate Change Strategy and Action Plan BMD Bangladesh Meteorological Department BWDB Bangladesh Water Development Board CEGIS Center for Environmental and Geographic Information Services EACC Economics of Adaptation to Climate Change GBM Ganges, Brahmaputra, and Meghna GCM General Circulation Model GIS Geographic Information System IPCC Intergovernmental Panel on Climate Change IWM Institute of Water Modelling MIROC Model for Interdisciplinary Research on Climate RCM Regional Climate Model VSL Value of Statistical Life Currency Equivalents 2009 US$1 = 70 Bangladesh takas (Tk.) Vice-President Isabel M. Guerrero Country Director Ellen A. Goldstein Sector Director John Henry Stein Sector Manager Herbert Acquay Task Team Leader Maria Sarraf Contents Executive Summary xiii Chapter 1. Monsoon Floods and Cyclones 01 Exposure to monsoon floods 01 Exposure to cyclones 03 Building resilience over the years 05 Added risk of climate change 06 Moving forward 06 Study objective and scope 06 Chapter 2. Added Inundation from Inland Monsoon Floods in a Changing Climate 09 Added risk of climate change 09 Changes in potential inundation zones and depths due to climate change 10 Population at risk 13 Chapter 3. Adaptation Cost: Inland Monsoon Floods 15 Infrastructure at added risk of monsoon flood inundation due to climate change 15 Roads 15 Cross-drainage road facilities 17 Railways 17 River embankments 18 Coastal polder drainage 18 Scour protection 19 Cost of added inundation from inland monsoon floods 19 Chapter 4. Added Inundation from Cyclones in a Changing Climate 21 Added risk of climate change 21 Changes in potential storm-surge zones and depths due to climate change 22 Coastal population at risk 24 x Chapter 5. Adaptation Cost: Cyclones 25 Infrastructure at added risk of storm-surge inundation due to climate change 25 Height enhancement of coastal polders 26 Afforestation protection of sea-facing polders 27 Multipurpose cyclone shelters 27 Cyclone-resistant private housing 28 Strengthened early warning and evacuation system 29 On further infrastructure investment 29 Cost of added inundation from cyclones and related storm surges 29 Chapter 6. Toward Adaptation and Investment Planning 31 References 33 Appendix: Impact of a 10-year-return-period Cyclone in Bangladesh by 2050 37 Tables Table 1 Total adaptation cost for inland monsoon floods (at 2009 prices) xvi Table 2 Total adaptation cost for cyclones and associated storm surges by 2050 (at 2009 prices) xvii Table 2.1 Inundation-area estimates out to 2050 11 Table 2.2 Additional inundation depths with climate change 12 Table 2.3 Vulnerable population estimates for inland monsoon floods 13 Table 3.1 Length of road (km) at added risk of inundation from climate change by 2050 16 Table 3.2 Adaptation cost by road type (million US$) 17 Table 3.3 Railway tracks at risk of inundation by 2050 with climate change 17 Table 3.4 Itemized cost of raising river embankments (million US$) 18 Table 3.5 Total adaptation cost for inland monsoon floods 20 Table 4.1 Vulnerable population estimates for cyclonic storm surges 24 Table 5.1 Estimated cost of enhancing height of coastal embankments (million US$) 27 Table 5.2 Total adaptation cost for cyclones and associated storm surges by 2050 30 Table A-1 Cost (US$) to enhance height of coastal embankments 39 Table A-2 Added potential damage and loss from an average cyclone-induced inundation in a changing climate by 2050 ($2009 prices) 41 Figures Figure 2.1 Comparison of risk-exposure zones for 24-hour duration floods 11 Figure 2.2 Change in inundation depths across Bangladesh 12 Figure 4.1 Tracks of major cyclones in 1960-2009 spanned Bangladesh's entire coastline. 22 Figure 4.2 Five cyclone tracks span Bangladesh's entire coastline under the climate-change scenario. 23 Figure 4.3 High risk area by 2050 in a changing climate (Source: IWM) 23 Figure 5.1 In a changing climate, 33 sea-facing and 26 interior polders will likely be overtopped by 2050. 26 Figure 5.2 Spatial locations of existing cyclone shelters in coastal areas 28 Boxes Box 1.1 History of Inland Monsoon Floods 02 Box 1.2 History of Cyclones and Related Storm Surges 04 xiii Executive Summary Bangladesh is one of the most climate cyclones Cyclonic storm surges are expected to vulnerable countries in the world. Situated in cover an additional 15 percent of coastal area, the delta of the Ganges, Brahmaputra, and with greater inundation depth. Without Meghna (GBM) rivers, the country is exposed to strengthening coastal polders, 6-8 million people a range of river and rainwater flood hazards due could be displaced by 2050 if sea-level rise is to climate variability, the timing, location, and higher than currently projected. extent of which depend on precipitation in the entire GBM basin. The country's topography is The Government of Bangladesh is fully extremely low and flat, with two-thirds of its land committed to global climate-change advocacy area less than 5 m above sea level. Low-lying and action, having already invested heavily in coastal districts along the Bay of Bengal are adaptation measures and policies. In recent particularly vulnerable to tidal flooding, cyclones, decades, the government has invested more than and related storm surges. Given that the current US$10 billion to protect its population and assets population of 150 million is expected to reach in the floodplains. Such measures as about 230 million by 2050*, any fur ther strengthening river embankments, building intensification of climatic variability will affect the emergency cyclone shelters, and developing a country in a significant way. world- class, community-based early warning system have significantly reduced the loss of life Climate change will likely increase the and livelihoods and property damage caused by exposure of densely populated, low-lying areas extreme weather events. Notwithstanding that to intensified flooding and cyclones. Since 1954, climate change may put all the recent gains in Bangladesh experienced 21 above-normal floods, resilience at incredible risk. 4 of which were exceptional and 2 catastrophic. The scientific consensus for the GBM basin is a The government recognizes intensification projected temperature rise of 1-30C and 20 of inland monsoon flooding and tropical percent more monsoon rainfall by 2050, cyclones in a changing climate as major climate suggesting that Bangladesh will be exposed to hazards requiring a rapid, strategic response. more severe inland flooding. The country is also The Bangladesh Climate Change Strategy and a global hotspot for tropical cyclones. A severe Action Plan (BCCSAP), adopted prior to the cyclone strikes the country every three years, on Copenhagen Summit in 2009, identified inland average. Increase in ocean surface temperature monsoon flooding and tropical cyclones and rising sea levels are predicted to intensify accompanied with storm surges as two of the three major climate hazards facing the country. * The estimate is based on a 1.15-percent annual population growth. xiv THE COST OF ADAPTING TO CLIMATE EXTREMES IN BANGLADESH Taking into account projected population For these two climate hazards, this study growth, the government acknowledges that integrated information on climate change, disaster preparedness and resilience must be population and assets at risk, growth scaled up to maintain the country's stable projections, and cost estimates. In each case, the growth path and thus avoid jeopardizing the first step was to demarcate the potential livelihoods and long-term health of the inundation zone and projected depth of Bangladesh people. inundation for a baseline scenario without climate change and one with climate change. The Study objective next step was to identify the critical populations Given the uncertain magnitude and timing of and infrastructure exposed to the added risk of the added risks from climate change, it is inundation in a changing climate. The final step essential to identify the costs of climate- was to quantify the cost of adapting these assets proofing Bangladesh's critical infrastructure to avoid further damage due to climate change.g from intensified monsoon floods and cyclonic storm surges. Previously, few if any detailed Inland monsoon floods studies have been developed on the costs of For inland monsoon floods, the 1998 climate-proofing the country's infrastructure exceptional flood, with a 90-year return period, assets from inland monsoon floods and was taken as the baseline scenario. This flood- cyclones. Most analytical work to date has been the most severe on record in terms of both confined to case studies, with relatively limited duration and inundation depth-was the sets of locations, impacts, and adaptation counterfactual against which future climate measures. change risk was measured. For the scenario with climate change, the MIROC 3.2 General This study aims to fill that knowledge gap by Circulation Model, under the A2 emissions providing detailed vulnerable population scenario of the Intergovernmental Panel on estimates and estimates of the incremental Climate Change which results in the largest costs of asset adaptation out to the year 2050. increase in runoff for Bangladesh, was used to It is part of a larger World Bank-supported study, predict changes in monthly precipitation and entitled Economics of Adaptation to Climate temperature between 1998 and 2050. To Change (EACC), funded by the governments of approximate the monthly precipitation and the United Kingdom, the Netherlands, and temperature over the entire GBM basin in 2050, Switzerland. This 2010 study takes the BCCSAP projections for each 50 km x 50 km grid covering as its starting point, building on and strengthening the basin was applied to the historical monthly the analytical models and quantitative assessment averages for 1998. tools used to support the plan's research and management theme. Two of the four discrete Risk exposure out to 2050 was identified areas developed for analysis and quantification under both the baseline and climate-change under the EACC study are inland monsoon scenarios. Transboundary flows and estimated floods and tropical cyclones and related storm runoffs from the GBM basin were simulated surges. using models developed at the Flood Forecasting g Given the lack of detailed, location-specific data on the functional status of existing infrastructure and the current risk of overtopping and breakdowns during a disaster, the focus of this analysis is to avoid further damage from additional inundation due to climate change. EXECUTIVE SUMMARY xv and Warning Centre of the Bangladesh Water change is likely to increase inundation depth in Development Board. The national flood model about half of land area, depths greater than 15 was used to generate flood levels, extent of cm are expected to occur in less than 0.5 inundation, and duration of extreme flood events percent of the country. Current spatial during the monsoon period. The results of daily distribution of infrastructure was taken as the inundation depth were synthesized to determine starting point for identifying which assets would the highest depths during the monsoon period, be most vulnerable to the added risk of identify the most vulnerable areas, and group inundation by 2050. them into five risk-exposure zones. Under the baseline scenario, 45 percent of land would be Cyclones under at least 0.3 m of water. Under the To approximate cyclonic storm surges in a climate-change scenario, the total flooded area changing climate by 2050, the study considered would increase by 4 percent, and in most a sea-level rise of 27 cm, increased wind speed flooded areas, inundation depth would also rise. of 10 percent, and landfall during high tide. To determine the number of people exposed Under the baseline scenario, tracks of 19 major to inland monsoon floods under the two historical cyclones that made landfall between scenarios at various inundation depths, the flood 1960 and 2009 were used, along with their risk exposure map was overlaid on the 2001 observed wind and pressure fields. Simulation population map, using Geographic Information modeling was used to generate the extent and System (GIS) software. In 2001, about 23 million depth of inundation from storm surges and people lived in rural areas with estimated associated flooding. Under the climate-change inundation depths greater than 0.3 m. By 2050, scenario, the same historical cyclones and that number is expected to fall to 19.2 million, affected coastal regions were used to simulate owing to urban migration. However, the area potential tracks out to 2050. Overlapping inundated is likely to expand with climate change, cyclone tracks covered the Sundarban coast, with an additional 1.9 million lives affected by the southwestern coast (Sundarban to Patuakhali), newly inundated areas. In a changing climate, Bhola and Noakhali coast in the Meghna Estuary, therefore, a total of 21.1 million rural people and eastern coast (Sitakunda to Banshkhali). An would be at risk of inundation depths greater artificial track was generated to cover the than 0.3 m, and most people living in inundated Sandwip coast and parts of the Noakhali and areas would be exposed to higher depths.‡ Chittagong coasts in the central part of the Meghna Estuary. Together, these five tracks were To estimate the cost of climate-proofing used to determine the inundation zones due to infrastructure-railways, river embankments, and climate change-induced storm surges. drainage structures-the added risk of flood inundation due to climate change was To determine potential future inundation determined, using GIS software. Areas with zones by 2050 under the climate-change large expected changes in inundation depth are scenario, the storm-surge model was run for the spread out across Bangladesh. Although climate five cyclone tracks. Based on simulation results, inundation maps for 2050 were generated. ‡ The estimates for exposed populations in 2050 are based on a 1.15-percent annual growth in rural and urban populations, applied uniformly across the country. These projections do not account for autonomous adaptation by rural households in response to changing flood-risk conditions or the implementation of land-use and coastal zone management policies put in place by the government over the past decade. xvi THE COST OF ADAPTING TO CLIMATE EXTREMES IN BANGLADESH Under the climate-change scenario, the insufficient to prevent large losses of road vulnerable area would be 55 percent greater infrastructure. In addition, the inadequacy of than under the baseline scenario, with an drainage facilities for these roads is likely to additional 2 m of inundation depth. worsen in a changing climate in the upfront. Furthermore, climate change will subject most of Currently, cyclonic storm surges expose 8 the country's rail network and river million people in coastal Bangladesh to embankments to 0.5 m of added inundation and inundation depths greater than 1 m. With increase drainage congestion in coastal polders upswing population growth, that figure would and scour depths of unprotected river banks likely increase 68 percent by 2050 under the (Table 1). baseline scenario. In a changing climate without further adaptation measures, nearly 17 million More than 83 percent of this adaptation people would be exposed to inundation depths cost, about US$2.72 billion, is for raising the greater than 1 m, and about 13.5 million to height of the road network. Additional cross- depths greater than 3 m. To identify the added drainage of coastal polders accounts for inundation risk to the extensive infrastructure another 13 percent, while the remaining that protects low-lying coastal areas-polders, measures-river embankment enhancement, cyclone shelters, and early warning and railway height enhancement, and road cross- evacuation systems-GIS software was used to drainage-together account for less than 4 overlay the best available, spatially-disaggregated percent of the total cost. data on current assets and activities with projected inundation zones for 2050 under the It should be noted that for the climate two scenarios. change scenario considered, these cost estimates for inland monsoon flood protection Adaptation cost: Inland monsoon floods provide a lower bound on the actual costs of adaptation as they do not include the added By 2050, an estimated US$3.3 billion will be adaptation required in urban areas and currently required to protect roads, railways, river unprotected river banks. Lacking location- embankments, and drainage infrastructure specific data on the functional status of existing against the added inundation from inland infrastructure and the current risk of monsoon floods due to climate change. Recent overtopping and breakdowns during a monsoon major floods have proven that Bangladesh's flood, this analysis could not quantify the standards for national and regional roads are adaptation deficit. Table 1 Total adaptation cost for inland monsoon floods (at 2009 prices) Cost component (million US$) Road height enhancement 2,718 Road cross-drainage 5 Railway height enhancement 27 River embankment enhancement 96 Cross-drainage of coastal polders 421 Total cost 3,267 1 01 Chapter Monsoon Floods and Cyclones Bangladesh is widely recognized as one of the severe flood occurs during the monsoon season, world's most climate vulnerable countries. submerging more than three-fifths of the land Situated in the delta of the Ganges, Brahmaputra, (GOB 2009). Since 1954, the country has and Meghna (GBM) rivers, the country is experienced 21 above-normal floods, 4 of which exposed to a range of climate variability, from were exceptional and 2 catastrophic (Box 2.1).1 seasonal droughts to severe monsoon floods, tropical cyclones and related storm surges. The most recent exceptional flood, which Natural disasters regularly strike, often resulting occurred in 2007, inundated 62,300 km2 or 42 in loss of life and severe damage to infrastructure percent of total land area, causing 1,110 deaths and economic assets. The crops and livelihoods and affecting 14 million people; 2.1 million ha of of the rural poor, including those living along standing crop land were submerged, 85,000 densely-populated coastlines, are especially houses completely destroyed, and 31,533 km of sensitive to climate hazards. The country faces roads damaged. Estimated asset losses from this numerous climate change-related challenges one event totaled US$1.1 billion (BWDB 2007). linked to the greater watershed beyond its Flooding in Bangladesh results from a borders. This chapter briefly reviews Bangladesh's complex set of factors, key among which are recent history of inland monsoon floods and extremely low and flat topography, uncertain cyclones and the risk of climate change to recent transboundary flow,2 heavy monsoon rainfall, and gains in adaptation. high vulnerability to tidal waves and congested drainage channels. Two-thirds of Bangladesh's Exposure to monsoon floods land area is less than 5 m above sea level. Each Bangladesh ranks as the sixth most flood-prone year, an average flow of 1,350 billion m3 of water country in the world (UNDP 2004). In an from the GBM basin drains through the country. average year, nearly one quarter of Bangladesh is During the summer monsoon season, when the inundated, with more than three-fifths of land country receives about four-fifths of its annual area at risk of floods of varying intensity (Ahmed rainfall, the three rivers have a combined peak and Mirza 2000). Every four or five years, a flow of 180,000 m3 per second.3 1 A flood whose inundation area exceeds 21 percent of Bangladesh's total land area has been classified as above normal; above- normal floods have been further divided into four subcategories: moderate (21-26 percent inundation area), severe (26-34 percent inundation area), exceptional (34-38.5 percent inundation area), and catastrophic (more than 38.5 percent inundation area) (Mirza 2002). 2 Fifty-seven international rivers flow into Bangladesh. 3 Surpassed only by that of the Amazon. 02 THE COST OF ADAPTING TO CLIMATE EXTREMES IN BANGLADESH Box 1.1 History of Inland Monsoon Floods The historical record of floods in Bangladesh indicates that a significant number of above-normal floods occurred between 1890 and 2007. Time-series analysis indicates that this above-normal flooding has not followed any regular pattern historically. From 1892 to 1922, there was frequent flooding, while the subsequent 50 years had few above-normal floods. Since 1950, however, the frequency of above-normal flood events has increased (Hofer and Messerli 2006). Extent of above-normal flooding in Bangladesh, 1950-2009 Source: CEGIS (2010). Statistics on recent floods show that the extent of inundation from severe floods may exceed two-thirds of total land area. Recent exceptional or catastrophic floods in Bangladesh Impact 1974 1987 1988 1998 2004 2007 2 Area affected (thousand km ) 53 57 90 100 56 62 % total land area inundated 37 40 63 69 39 42 Millions of people affected 30 30 47 31 33 14 Fatalities (no.) 28,700 1,657 2,379 918 285 1,110 Houses damaged (thousands) na 989 2,880 2,647 895 1,000 Roads damaged (km) na na 13,000 15,927 27,970 31,523 Crops damaged (millions of ha) na na 2.12 1.7 1.3 2.1 Asset losses (million US$) 936 1,167 1,424 2,128 1,860 1,100 GDP (million US$) 12,459 23,969 26,034 44,092 55,900 68,400 Asset losses (% of GDP) 7.5 4.9 5.5 4.8 3.3 1.6 Return period (years) 9 13 55 90 12 14 Sources: Islam and Mechler (2007); BWDB (2007). The exceptional flood of 1998, the most severe on record in terms of both depth of inundation and duration, 2 2 affected 69 percent of total land area. Nearly 100,000 km , including 6,000 km of standing crop lands, were flooded; about 1 million households suffered property damage, and 16,000 km of roads and 6,000 km of embankments were affected. About half of the country was under water for up to 67 days, with inundation depth reaching up to 3 m. All but 11 of the country's 64 districts experienced flooding of varying magnitude. Major factors contributing to such extreme devastation included lingering intensive rain in July and August 1998; simultaneous above-danger flow levels of the Ganges, Brahmaputra, and Meghna rivers; backwater effects resulting from synchronization of peak flow of the three rivers and high tides; and the La Niña effect at that time (World Bank 2010). CHAPTER 1: MONSOON FLOODS AND CYCLONES 03 Exposure to cyclones literature indicates a 1.5-9 m height range Bangladesh is also a global hotspot for tropical during various severe cyclones. Surges that cyclones.4 Nearly every year, cyclones hit the make landfall during high tide are even more country's coastal regions in the early summer devastating. In general, it has been observed (April-May) or late rainy season (October- that the frequency of a 10-m high wave (surge November). Between 1877 and 1995, Bangladesh plus tide) along the Bangladesh coast is about was hit by 154 cyclones, including 43 severe once every 20 years, while a wave with a 7-m cyclonic storms, 43 cyclonic storms, and 68 height occurs about once in 5 years. In tropical depressions.5 On average, a severe addition, wind-induced waves of up to 3.0 m in cyclone (26-34 percent inundation area) strikes height may also occur under unfavorable the country every three years (GOB 2009) (Box conditions (MCSP 1993). 1.2). Bangladesh is on the receiving end of about In 2007, Cyclone Sidr, a 10-year return two-fifths of the world's total impact from cyclone, struck the southwest coast of storm surges (Murty and El-Sabh 1992). The Bangladesh6 with an average wind speed of 223 reasons for this disproportionately large impact km per hour, causing 3,406 casualties, 55,282 include the recurvature of tropical cyclones in injuries and affecting 8.9 million people. It the Bay of Bengal; the wide, shallow continental damaged 0.6 million ha of standing crop land, shelf, especially in the eastern par t of the completely destroyed 537,775 houses, and country;8 the high tidal range;9 the triangular submerged 8,075 km of roads. Estimated shape at the head of the Bay of Bengal, which damages and losses from Cyclone Sidr totaled helps to funnel sea water pushed by the wind US$1.67 billion (GOB 2008). toward the coast, causing fur ther surge Records indicate that the greatest damage amplification; the nearly sea-level geography of during cyclones has resulted from the the coastal land; and the high-density inundation caused by cyclone-induced storm population and coastal protection system (Ali surges.7 Though time-series records of storm- 1999).10 surge height are scarce in Bangladesh, existing 4 The United Nations Development Programme (UNDP) has ranked Bangladesh as the world's most vulnerable country to tropical cyclones (UNDP 2004). 5 Based on the observed maximum sustained surface wind measured at a height of 10 m averaged over 3 minutes, tropical storms are classified as super cyclonic (wind speed over 220 km per hour), very severe cyclonic (119-220 km per hour), severe cyclonic (90-119 km per hour), cyclonic (60-90 km per hour), deep depression (51-59 km per hour), and depression (32-50 km per hour) (IMD 2010). 6 The four worst affected districts were Bagerhat, Barguna, Patuakhali and Piroipur. The seven moderately affected districts were Barishal, Bhola, Gopalganj, Jhalkathi, Khulna, Madaripur and Shariatpur. 7 Storm surge refers to the temporary increase in sea height in a particular locality due to extreme meteorological conditions (i.e., low atmospheric pressure and/or strong winds) (IPCC 2007). 8 This wide shelf amplifies the storm surges as the tangential sea-level wind-stress field associated with the tropical cyclone pushes the sea water from the deep water side onto the shelf; being pushed from the south by wind stress, the water has no place to go but upwards, which creates the storm surge. 9 Records indicate 7-8 m high tide in the Sandwip Channel. 10 Most surge amplifications occur in the Meghna estuarine region. 04 THE COST OF ADAPTING TO CLIMATE EXTREMES IN BANGLADESH Box 1.2 History of Cyclones and Related Storm Surges Cyclones pose a threat to lives and property in low-lying coastal regions of Bangladesh. From 1960 to 2009, 19 major cyclones made landfall in the country; since 1995, its coast has been hit by five severe cyclones.* Risk from major cyclones in 1960-2009 spanned Bangladesh's entire coastline Source: IWM The greatest damage during cyclones has resulted from the inundation caused by cyclone-induced storm surges. Existing literature indicates a 1.5-9 m height range during various severe cyclones. Storm- surge heights of 10 m or more have not been uncommon; for example, the 1876 Bakerganj cyclone had a reported surge height of 13.6 m (SMRC 2000). Typical storm-surge features of cyclones in Bangladesh Wind velocity (km/hr) Surge height (m) Limit to coastal inundation (km) 85 1.5 1.0 115 2.5 1.0 135 3.0 1.5 165 3.5 2.0 195 4.8 4.0 225 6.0 4.5 235 6.5 5.0 260 7.8 5.5 At present, there is a 10-percent chance each year that Bangladesh will be hit by a super cyclonic storm. The extent of storm-surge inundation from Cyclone Sidr, a 10-year-return-period cyclone that hit in 2007, was 8.7 percent more than the historical average for similar storms. CHAPTER 1: MONSOON FLOODS AND CYCLONES 05 Probability of higher-intensity cyclones in Bangladesh Cyclonic storm surge Wind speed (km/hr) Annual minimum probability (%) Super > 220 10 Very severe 119-220 20 Severe 90-119 30 * For details on major cyclones that crossed Bangladesh from 1960 to 2009, see Dasgupta et al., Vulnerability of Bangladesh to Cyclones in a Changing Climate: Potential Damages and Adaptation Cost, Appendices 2 and 3. World Bank, Washington, DC (2010b). Building resilience over the years improved macroeconomic management, The Government of Bangladesh is fully increased resilience of the poor and efficient committed to improving the country's resilience disaster management and flood protection to climate risks and has invested heavily in infrastructure (World Bank, 2010). Damages adaptation measures and policies. A significant from the 1974 flood, a 1-in 9-years event, totaled investment has been made in river 7.5 percent of GDP; by contrast, the exceptional embankments, emergency shelters, and disaster flood of 1998, which had double the inundation relief operations; and the country has established area, produced significantly less damage, at 4.8 infrastructure design standards and building percent of GDP. The increased resilience of codes.11 Bangladesh now has a world-class, Bangladesh to natural disasters is also apparent community-based early warning system, and has when recent GDP and agricultural growth rate built cyclone shelters on stilts to allow storm trends are examined with respect to the timing surges to flow underneath. of flood events. Until the 1990s, GDP and agricultural growth rates sharply declined Rural residents in flood-prone areas have also following major flood events. However, the adapted by building their houses on raised relative effects of major floods have diminished mounds above the normal flood level. Rural since 1990.12 In fact, positive growth rates were roads, schools, and medical centers have been sustained even after the devastating 1998 flood. raised above normal flood level, where feasible. Changes in cropping patterns, adequate reserves Farmers have adjusted their cropping patterns to of food grains and increased rice imports by take advantage of the flood water, switching from both the public and private sectors have also traditional low-yielding, deepwater (aman) rice to contributed to offset the negative effects of high-yielding, irrigated (boro) rice. major flood events. Community-based early warning system and emergency cyclone shelters In general, the relative severity of the impacts have significantly reduced deaths and injuries from natural hazards in Bangladesh has during natural disasters over time. decreased substantially since 1970s as a result of 11 The Bangladesh Water Development Board (BWDB) has developed design manuals for embankment and flood control and drainage infrastructure. 12 Despite several major disasters, Bangladesh remains among the few countries that have avoided a single year of negative growth since the 1990s. 06 THE COST OF ADAPTING TO CLIMATE EXTREMES IN BANGLADESH Added risk of climate change invested heavily in adaptation measures and These gains may be at risk if the severity of adoption of policies to address the effects of natural disasters increases with climate change. more frequent and destructive water-related The effects of climate change are projected to weather events. The Bangladesh Climate Change exacerbate Bangladesh's vulnerability to severe Strategy and Action Plan (BCCSAP), adopted monsoon floods and cyclonic storm surges prior to the Copenhagen Summit in 2009, (GOB 2009). Across the 16 General Circulation identified inland monsoon flooding and tropical Models (GCMs) and three emission scenarios cyclones and related storm surges as two of the considered by the Intergovernmental Panel on three major climate hazards facing the country; Climate Change (IPCC), the consensus is on ensuring adequate flood protection infrastructure predicted 1-3? C temperature rise for the GBM is one of six pillars identified in the BCCSAP basin by 2050 (IPCC 2007). Though estimates (GOB 2009). on precipitation changes vary widely across the The government has already committed GCMs, most indicate up to 20 percent more about US$200 million from its own resources to rainfall during the monsoon season (July- establish a climate change fund, called the September). Heavier, more erratic rainfall in the Bangladesh Climate Change Trust Fund, to address GBM system during the monsoon season is the priority adaptation needs of the most expected to aggravate the extent of inland vulnerable sectors. It recognizes that water- flooding in Bangladesh. Increase in ocean surface related climate hazards require a rapid, strategic temperature and rising sea levels are likely to response to maintain the country's stable growth intensify cyclonic storm surges and further path and thus avoid enormous adverse effects on increase the depth and extent of storm surge- livelihoods and the long-term health of the induced coastal inundation (IPCC 2007; World Bangladesh people, including the poorest and Bank 2010). most vulnerable families. More intense inland and coastal floods may over top and breach embankments, causing Study objective and scope greater erosion of river banks, resulting in loss Given the large uncer tainties about the of homes and agricultural land, and more magnitude and timing of the added risks from sedimentation of riverbeds, leading to drainage climate change in Bangladesh, it is essential to congestion and water logging. Damages and identify the costs of adapting the country's losses will likely be geographically concentrated critical infrastructure to intensified monsoon in areas that also have the highest flooding and storm-surge patterns. To date, concentrations of the poor and most vulnerable however, few if any systematic studies have been populations, whose livelihoods, including developed on the costs of climate-proofing agriculture and fisheries, are extremely weather- Bangladesh's infrastructure. Previously, most sensitive. analytical work has been confined to case studies, with relatively limited sets of locations, impacts, Moving forward and adaptation measures (Khalil 1992; Hoque Keenly aware of the potentially disastrous 1992; Ali 1999). The present study seeks to fill in environmental and socioeconomic consequences the knowledge gap by providing estimates of of future climate extremes, the Government of vulnerable area, population at risk, and itemized Bangladesh is fully committed to global climate- incremental costs of adapting critical change advocacy and action, having already infrastructure to intensified monsoon floods and CHAPTER 1: MONSOON FLOODS AND CYCLONES 07 cyclones and related storm surges out to the functional status of existing infrastructure and the year 2050. current risk of overtopping and breakdowns during a disaster, the focus of the study was to To itemize the estimates of adaptation cost to avoid further damage from additional inundation climate change, this study integrates information due to climate change. on climate change, hydrodynamic models, and geographic overlays to assess the vulnerability of The remainder of the report is organized as Bangladesh to larger monsoon floods and larger follows. Chapter 2 details the potential storm surges and sea-level rise by 2050. In each inundation zones and depths and identifies the case, the study first demarcated the potential population at added risk from monsoon floods in inundation zone and projected depth of a changing climate; Chapter 3 then quantifies the inundation for both a baseline scenario without cost of climate-proofing infrastructure for inland climate change and one with climate change out monsoon floods out to the year 2050. Similarly, to the year 2050. It then identified the critical Chapter 4 details the potential inundation zones impact elements and populations and and depths and populations at added risk from infrastructure exposed to the added risk of cyclonic storm surges in a changing climate; while inundation in a changing climate. Finally, it Chapter 5 identifies critical infrastructure at quantified the cost of adapting infrastructure to added risk and provides the total and itemized avoid further damage due to climate change.13 At adaptation cost estimates. Finally, Chapter 6 the outset, it should be noted that in the absence concludes and suggests broad policy of detailed location-specific data on the recommendations. 13 This study is part of a larger World Bank-supported study, entitled the Economics of Adaptation to Climate Change (EACC). The EACC study was developed in four discrete areas with varying degrees of analytical depth and quantification: (i) inland monsoon floods, (ii) tropical cyclones and related storm surges, (iii) impacts on agriculture and food security, and (iv) local perspectives on adaptation (World Bank 2010). 2 09 Chapter Added Inundation from Inland Monsoon Floods in a Changing Climate Bangladesh has extensive infrastructure- Most climate-related research points to a including embankments, shelters, and early warmer, wetter GBM basin in the coming warning and evacuation systems-to protect its decades. Increased rainfall in the upper GBM population and assets in the floodplains. Such basin is expected to result in higher river flows protective measures have significantly reduced from Nepal, India, China, and Bhutan into the loss of life and livelihoods and property Bangladesh (IPCC 2007). Mirza and Dixit (1997) damage resulting from extreme weather events estimated that a 20 C warming, combined with a over time. Yet the warmer, wetter future 10-percent increase in precipitation, would projected for the GBM basin suggests that increase runoff by 19 percent for the Ganges, 13 future inundation from above-normal flood percent for the Brahmaputra, and 11 percent for events will exceed the country's current level of the Meghna. In Bangladesh, depth of flooding disaster preparedness. would be pronounced in the lowlands of southwest Dhaka, Rajshahi, and Sylhet, and the This chapter briefly reviews the forecast of districts of Faridpur, Pabna, Comilla, and monsoon floods in a changing climate, details the Mymensingh. In a more recent study, Mirza et al. potential inundation zones and depths, and (1998) repor ted a 5-percent increase in identifies populations at added risk from this precipitation for the GBM basin, combined with climate hazard. 10 C temperature rise, could result in up to a 20- percent increase in flooded area. Severity of Added risk of climate change extreme floods, such as the 20-year flood event, Bangladesh is located at the mouth of the GBM is estimated to increase marginally. Another study basin. The entire GBM basin (an average of 1,350 conducted in 1998 concluded that a 1-20 billion m3 of water flow per year) drains through percent increase in monsoon rainfall will increase Bangladesh. Hence, the timing, location, and surface runoff by 20-45 percent in Bangladesh extent of flooding depend not only on the 7 (Ahmed and Alam 1998).1 In addition, for percent of precipitation that occurs within Bangladesh alone, the median predictions of the Bangladesh's borders but on that of the entire 16 GCMs for three emission scenarios GBM basin. considered by the IPCC point to a warming of 1 An earlier study indicated that a 10-percent increase in monsoon precipitation in Bangladesh could increase runoff depth by 18-22 percent, resulting in a sevenfold increase in the probability of an extremely wet year (Qureshi and Hobbie 1994). 10 THE COST OF ADAPTING TO CLIMATE EXTREMES IN BANGLADESH 1.550 C and a 4-percent increase in precipitation temperature over the entire GBM basin in by 2050 (Yu et al. 2010).2 Hence, forecasts by 2050, precipitation and temperature projections most of the climate-related research indicate for each 50 km x 50 km grid covering the basin vulnerability of Bangladesh to severe monsoon were applied to the historical monthly averages floods will increase further with climate change for 1998. (World Bank 2010). To identify the inundation risk exposure out Changes in potential inundation zones to 2050 under both the baseline and climate- and depths due to climate change change scenarios, a four-step process was used. First, transboundary flows and estimated runoffs To assess the impact of climate change on from the GBM river basins were simulated using inundation from monsoon, this study first the GBM model in the MIKE Basin platform.3 demarcated the potential inundation zone and projected depth of inundation for both a Second, to generate flood levels, the extent baseline scenario without climate change and of inundation, and the duration of extreme one with climate change. The 1998 exceptional flood events for each 300 m x 300 m grid flood, with a 90-year return period, was taken as during the monsoon period, the National Flood the baseline scenario. This was the Model of Bangladesh, developed by counterfactual against which future climate Bangladesh's Flood Forecasting and Warning change risk was measured. For the scenario Centre, was used.4 with climate change, the Model for Interdisciplinary Research on Climate (MIROC) Third, the results of daily inundation depth 3.2 GCM, under the A2 emissions scenario of were synthesized to determine the highest the IPCC, was used to predict changes in depth for each grid point during the monsoon monthly precipitation and temperature between period and to identify which areas would be 1998 and 2050. It should be noted that among vulnerable to floods of a minimum, 24-hour the 16 GCMs, the MIROC 3.2 results in the duration.5 largest increase in runoff for Bangladesh. To Finally, the grid points were grouped into five approximate the monthly precipitation and risk exposure zones (Figure 2.1). 2 The resolution of the models varies with about five grid boxes typically covering Bangladesh. The national values are weighted averages, with the weights equal to the percentage of each grid that is within Bangladesh. 3 This model was developed in 2006 at the BWDB's Flood Forecasting and Warning Centre. For this research, the Institute of Water Modeling updated the model to include river alignments of the GBM basins, using available physical maps of India, Nepal, and Tibet. Basin subcatchments were re-delineated using the Digital Elevation Model, based on the SRTM-version 3. The model was first calibrated using the 2005 year-round hydrological feature and validated for 2006 and 2007; further updating used hydrological data from 2009 (the most recent year). 4 The hydrodynamic model, based on the current national Digital Elevation Model, included all of Bangladesh's important rivers and canals (khals) (10,235 km), floodplain routing channels (1,147 km), and link channels; simulations included all of the country's existing flood control and drainage infrastructure and flood protection measures. Bathymetries of the rivers were updated, incorporating the latest available cross-sections; bathymetries of floodplain routing channels were taken from the national land terrain model of the Flood Action Plan. Flood forecasting included data from more than 200 rainfall stations and some 30 evapotranspiration stations. 5 The choice of 24 hours was based on the potentially severe damage to roads, embankments, and rural houses that typify floods of this duration. Models to reliably determine duration beyond a few days are currently unavailable. This analysis does not account for urban or flash floods. CHAPTER 2: ADDED INUNDATION FROM INLAND MONSOON FLOODS IN A CHANGING CLIMATE 11 Figure 2.1 Comparison of risk-exposure zones for 24-hour duration floods Baseline Scenario Climate-change Scenario Source: IWM Estimates indicate that under the baseline scenario, 45 percent of land would be under at least 0.3 m of water. Under the climate-change scenario,6 the total flooded area would increase by 4 percent; more importantly, the inundation depth in most flooded areas would rise (Table 2.1). 7 Table 2.1 Inundation-area estimates out to 2050 Baseline scenario Climate-change scenario Change due to climate Inundation (m) km2 % total area km 2 % total area km 2 % total area Flood free 69,439 52 64,550 49 (4,889) (3) F0 (0.1-0.3) 2,950 2 2,251 2 (699) F1 (0.3-0.9) 14,123 11 11,975 9 2,148 (2) F2 (0.9-1.8) 19,118 14 20,723 15 1,605 1 F3 (1.8-3.6) 22,115 16 26,153 19 4,038 3 F4 (> 3.6) 5,777 4 7,870 6 2,093 2 Total flooded area 60,750 45 66,362 50 5,588 5 6 MIROC 3.2 GCM and A2 emissions scenario 7 Areas inundated to depths greater than 0.9 m increase from 34 percent of total area under the baseline scenario to 40 percent under the climate-change scenario. At the peak period, land distribution is about the same as for the 24-hour duration flood. 12 THE COST OF ADAPTING TO CLIMATE EXTREMES IN BANGLADESH Areas with large expected changes in inundation depth are spread out across the country (Figure 2.2). Figure 2.2 Change in inundation depths across Bangladesh Source: IWM Further scrutiny of estimates indicates that, although climate change is likely to increase inundation depth in about half of Bangladesh, depths greater than 15 cm are expected to occur in only 544 km2, or less than 0.5 percent of the country (Table 2.2). Table 2.2 Additional inundation depths with climate change Added inundation depth (cm) Area (km2) Share of total area (%) No change 70,249 52.6 1-5 56,102 42.0 5-10 5,841 4.4 10-15 786 0.6 > 15 544 0.4 Total change 133,522 100.0 CHAPTER 2: ADDED INUNDATION FROM INLAND MONSOON FLOODS IN A CHANGING CLIMATE 13 Population at risk To determine the number of people exposed to inland monsoon floods under the two scenarios at various depths of inundation, the flood risk exposure map was overlaid on the 2001 population map, using GIS software. In 2001, about 23 million people lived in rural areas with estimated inundation depths greater than 0.3 m.8 Under the baseline scenario, that number would fall to 19.2 million by 2050, owing to urban migration. However, in a changing climate, 1.9 million more people would be affected in the newly inundated areas, implying that 21.1 million rural people would be at risk of inundation depths greater than 0.3 m. This is 9 percent more than under the baseline scenario but about 9 percent less than the current figure (Table 2.3). Table 2.3 Vulnerable population estimates for inland monsoon floods Inundation Population Population exposed Projected Change (%) level (m) exposed under in 2050 under population between baseline scenario* baseline scenario exposed in 2050 baseline and under climate- climate- change change scenario scenarios in 2050 F0 (0.1-0.3) 1,009,898 843,729 681,031 -19 F1 (03.-0.9) 6,721,555 5,615,588 4,566,517 -19 F2 (0.0-1.8) 8,490,523 7,093,488 8,108,952 14 F3 (1.8-3.6) 7,105,158 5,936,072 7,543,397 27 F4 (> 3.6) 669,027 558,945 899,066 61 Total exposed population 22,986,263 19,204,093 21,117,932 9 * According to the 2001 population census (BBS 2007). Most people living in inundated areas, It should be noted that the estimated however, would be vulnerable to higher population exposed in 2050 presented above is inundation depths. For example, 16.6 million based on an expected annual growth rate of 1.15 people would be exposed to inundation depths percent for rural and urban populations. This greater than 0.9 m, 22 percent more than under projection does not account for autonomous the baseline scenario. This figure would be offset adaptation by rural households in response to by a 19-percent decline in the population living in changing flood-risk conditions or recently areas with inundation depths less than 0.9 m. initiated government land-use and coastal-zone management policies now being implemented. 8 The exposed population count, estimated at the district (Thana) level, uses the population density and total area that fall into each risk zone. The total exposed population is the sum of the exposed population across all thanas. 3 15 Chapter Adaptation Cost: Inland Monsoon Floods The estimates of area and population at added shifts away from agriculture toward industry and risk from inland monsoon floods in a changing services-across the country. The zones with climate, presented in the previous chapter, point added risk exposure from inundation due to to Bangladesh's need for greater flood climate change were overlaid on the preparedness. Based on these inundation area infrastructure map, using GIS software. For estimates, the study quantified the cost of infrastructure with a large spatial extent (e.g., climate-proofing infrastructure for inland roads, railways, and river embankments), the monsoon floods out to the year 2050. This exposure estimate was measured by the asset's chapter reviews how critical infrastructure at risk spatial extent in kilometers. For drainage were identified and then provides the total and structures (e.g., culverts), the stock exposed in itemized cost estimates of climate-proofing them. each inundation risk zone was a count of the number of assets located in that zone. Infrastructure at added risk of monsoon flood inundation due to climate change The next sections present itemized estimates of adaptation costs for roads, cross-drainage road To estimate the cost of climate-proofing facilities, railways, river embankments, drainage infrastructure, the added risk of inundation due within coastal polders, and scour protection out to climate change was determined, taking the to the year 2050. All estimates are indicated in difference between the baseline and climate- 2009 prices. change inundation depths for each 300 m x 300 m grid. The infrastructure analyzed included Roads roads, railways, river embankments, and drainage infrastructure. Current spatial distribution of National and regional roads of Bangladesh were infrastructure was taken as the starting point for designed to withstand floods with a 50-year identifying which assets in a changing climate return period, while feeder roads were designed would be most vulnerable to the added risk of to be built above normal flood levels (Siddiqui inundation by 2050.1 The stock of infrastructure and Hossain 2006). Yet recent major floods have in 2050 was then projected by uniformly applying proven the insufficiency of these standards to expected changes in the economy-including prevent large infrastructure losses. Road damage population and income growth and structural from the exceptional flood of 1998 alone 1 The best available spatially-disaggregated maps and data for these assets were acquired from various public sources, including Bangladesh Railways, Bangladesh Water Development Board, Local Government Engineering Department, Center for Environmental and Geographic Information Services, Public Works Department, Roads and Highways Department, Water Resources Planning Organization, and the World Bank. 16 THE COST OF ADAPTING TO CLIMATE EXTREMES IN BANGLADESH accounted for 15 percent of total damages or the existing network.2 The road length (in about 0.7 percent of GDP (Islam and Mechler kilometers) exposed to added inundation risk 2007). Hence, the concern is that inundation risks from climate change was estimated for various of roads will be aggravated with climate change. road types using GIS overlays of added risk-zone maps over existing road network maps (Table In the absence of long-term planning for 3.1). In 2050, about 2 percent of roads will be additional new roads, this study assumed that, by subject to added inundation greater than 1 m; 2050, total road length in Bangladesh will while 87 percent will be exposed to 0.5 m of increase over existing stock by another 25 additional inundation due to climate change. percent; the assumed 25-percent expansion of the road network was applied uniformly across Table 3.1 Length of road (km) at added risk of inundation from climate change by 2050 Added Feeder Feeder inundation road road Share depth (type A) (type B) National Regional Rural Total of total 0-0.5 6,175 4,203 998 587 11,065 23,027 87% 0.5-1.0 734 515 194 86 1,315 2,844 11% 1.0-1.5 72 68 11 6 189 346 1% 1.5-2.0 24 19 1 3 89 137 1% 2.0-2.5 7 4 0 1 17 30 - 2.5-3.0 7 1 0 0 8 16 - All exposed 7,019 4,809 1,204 683 12,683 26,400 100% Share of all exposed 27% 18% 5% 3% 48% 100% The estimated adaptation cost for elevating the entire road3 network to offset the added risk of inundation due to climate change is Tk. 190 billion (US$2.72 billion). National and regional roads account for about 12 percent of this total, while rural and feeder roads comprise the remaining 88 percent (Table 3.2). 2 Bangladesh already has one of the densest road networks in the world; however, road quality is poor. Most new investments in road infrastructure are likely to be for upgrading roads to higher standards (e.g., by paving unpaved roads), rather than expansion. It has been further assumed that all the rural roads will be paved by 2050. 3 The cost of raising roads to avoid further inundation has been calculated based on the following unit costs: wearing course 50 mm thick of Tk 8,350 /m3; base course 50 mm thick Tk 7,899 /m3; aggregate base (type I) 100 mm Tk 2,819 /m3 ; aggregate base (type II) 100 mm Tk 2,232 /m3, road excavation Tk 184/m3 and earth fill from borrow pit Tk 124 /m3. Calculations have been made for each division (Barisal, Chittagong, Dhaka, Khulna, Rajshahia and Sylhet). CHAPTER 3: ADAPTATION COST: INLAND MONSOON FLOODS 17 Table 3.2 Adaptation cost by road type (million US$) Added Feeder Feeder inundation road road Share depth (type A) (type B) National Regional Rural Total of total 0-0.5 770 449 184 94 854 2,351 87% 0.5-1.0 95 57 37 14 106 310 11% 1.0-1.5 10 8 2 1 16 37 1% 1.5-2.0 3 2 0 <1 8 14 1% 2.0-2.5 1 1 0 0 2 3 0% 2.5-3.0 1 0 0 0 1 2 0% All exposed 818 517 224 110 968 2,718 100% Share of all exposed 32% 19% 8% 4% 36% 100% Cross-drainage road facilities Railways Bangladesh's roads currently lack sufficient Bangladesh Railways has no plans to expand its facilities to permit cross-drainage of flood water. network in the foreseeable future, with the With the increased flood-water volume exception of doubling the track between Dhaka expected in a changing climate, more culverts and Chittagong over the next few years. Thus, and regulators will be needed, and some culverts this study assumed that the country's rail will need to be raised to permit the free flow of network in 2050, including the Dhaka-Chittagong water. Deeply inundated areas (more than 0.9 expansion, would remain the same. The rail m) are expected to increase another 7,735 km2, length (in kilometers) exposed to added and each 1.5 m x 1.8 m drainage structure can inundation risk from climate change was drain about 10 km2, at a cost of Tk. 15 million. estimated for various track types using GIS Thus, 775 new drainage structures will be overlays of added risk-zone maps on existing needed to drain the added, deeply inundated railway maps (Table 3.3). In 2050, less than 2 areas due to climate change, at a total cost of Tk. percent of tracks will be subject to added 11,625 million (US$ 166.07 million). inundation greater than 1 m; yet 85 percent will Furthermore, 315 additional culverts will need to be exposed to 0.5 m of additional inundation be raised, at a cost of 1 million each, for a total due to climate change. Table 3.3 Railway tracks at risk of inundation by 2050 with climate change Track Additional inundation depth (m) gauge type 0- 0.5- 1.0- 1.5- 2.0- 2.5- (km) 0.5 1.0 1.5 2.0 2.5 3.0 >3.0 Total Meter 173.3 10.8 2.4 1.7 - - - 188.1 Broad 205.8 35.0 7.0 - - 0.4 0.3 248.5 Double 224.7 43.0 2.6 0.5 0.3 0.4 - 271.4 Total track 603.8 88.8 11.9 2.1 0.3 0.9 0.3 708.1 18 THE COST OF ADAPTING TO CLIMATE EXTREMES IN BANGLADESH Thus, most rail tracks-broad-, meter-, and percent (5,088 km) will be subject to inundation double-gauge-will need to be raised more than depths of up to 0.5 m and less than 1 percent 0.5 m, which increases the cost of earthwork.4 (29 km) to depths of more than 1 m. The bulk of For tracks raised 0.5-1 m, the cost of earthwork the cost of raising embankments to various per kilometer of rail track is US$20,539 for inundation depths to offset the added risk of broad- and double-gauge and US$16,821 for climate change is for required earthwork (Tk. meter-gauge. The total cost of raising railway 125 per m3); other costs include compaction (Tk. tracks to offset the added risk from climate 60 per m3) and turfing (Tk. 25 per m2) (Table change is US$27 million ($11 million for double- 3.4). The total cost for raising embankments is Tk. gauge, $10 million for broad-gauge, and $6 6,727 million (US$96 million). million for meter-gauge tracks). Coastal polder drainage River embankments Higher precipitation during the monsoon season The Bangladesh Water Development Board and rising sea level in a changing climate are (BWDB) currently maintains 9,943 km of river expected to increase drainage congestion in embankments, 5,111 km of drainage canals, and Bangladesh's 123 existing coastal polders (areas 13,949 flood control/regulating structures. with a dyke).5 In this study analysis, trial Embankments protect agricultural land, major simulations were conducted for four coastal Table 3.4 Itemized cost of raising river embankments (million US$) Additional inundation depth (m) Task 0-0.5 0.5-1.0 1.0-1.5 Total Earthwork 55 9 1 65 Compaction 26 4 1 31 Turfing 0 - 0 0 Total cost 81 13 2 96 cities, and small towns from 10-, 15-, and 50-year polders to determine the average number of return floods. Presently, the BWDB does not additional vents needed to drain water inside the anticipate expanding embankment length polder owing to the added congestion from through 2050 (BWDB 2003). By overlaying GIS climate change. In each simulation, the length of maps of added inundation risk zones on maps of opening under the climate-change scenario was existing embankments, this study found that, of adjusted to reduce the water depth inside each the 5,421 km of embankments exposed to the polder to the level under the baseline scenario. added inundation from climate change, 94 4 The process of raising rail tracks involves removing and replacing the ballast, rail, and other heavy iron works; dismantling and replacing the tracks; procuring earthwork with sand and ballast; spreading; and four-stage mechanical temping. See Dasgupta et al., Climate Proofing Infrastructure in Bangladesh: The Incremental Cost of Limiting Future Inland Monsoon Flood Damage, Table 8; World Bank, Washington, DC (2010a). 5 The cost of rehabilitating inoperative water regulators in coastal polders or adding new ones to meet the drainage needs under the baseline scenario are not part of the adaptation cost due to climate change. CHAPTER 3: ADAPTATION COST: INLAND MONSOON FLOODS 19 Thus, the adaptation measure is the added length Though expensive, infrastructure investments are of the opening needed to ensure the same long-lived and yield large benefits when designed drainage conditions for both scenarios. The appropriately. Hence, it is essential to develop number of additional vents required for the four appropriate standards commensurate with the trials (7, 17, 24, 51) was computed by dividing the likely climate risks over expected asset lives and length of opening by the width of each vent update them over time, as new research results (1.52 m). Under the climate-change scenario, become available. For example, the prospect of 1,475 additional vents, at a cost of Tk. 20 million more intense precipitation has implications for each, will be required to drain the additional unpaved roads, especially in rural areas, which are volume of monsoon flood water from the vulnerable to being washed away by floods and identified polders.6 The total cost of additional heavy rainfall. Single-lane, sealed roads have a drainage regulators in coastal areas is Tk. 29,500 higher capital cost, but provide a more reliable million (US$421.4 million). all-weather network with lower maintenance costs. As new research results increase the Scour protection certainty of an area's flooding risk, design Erosion of Bangladesh's unprotected river banks standards for roads in that area should be raised is expected to increase in a changing climate, as accordingly. Similarly, embankments should be confirmed by previous experience (CEGIS 2010). strengthened beyond their current protective The BWDB estimates that the maximum capacity as the added risk from floods becomes discharge of the Ganges, Brahmaputra, and more certain. Meghna rivers will increase by 17, 20, and 8 percent, respectively, with increased scour depths Cost of added inundation from inland of 1.87, 0.96, and 1.13 m (BWDB 2003). monsoon floods Increased scour depth, in turn, is expected to Recent major floods have proven that raise the annual operation and maintenance Bangladesh's standards for national and regional costs of existing river bank protection works by roads are insufficient to prevent large losses of 6.8 percent, due to the added requirement of road infrastructure. In addition, the inadequacy of launching apron. drainage facilities for these roads is likely to worsen in a changing climate. Furthermore, Over the past two years, the BWDB required climate change will subject most of the country's Tk. 1,045 million (US$14.9 million), on average, rail network and river embankments to 0.5 m of to protect against scouring. In a changing climate, added inundation and increase drainage the annual protection cost is expected to rise by congestion in coastal polders and scour depths US$1 million to Tk. 1,116 million (US$15.9 of unprotected river banks. million).7 6 As per discussions with the local experts, it has been assumed that installation of additional vents is not necessary when inundation depth is less than 0.9 m as water drains relatively quickly. 7 Erosion of unprotected river banks could not be estimated for lack of relevant data. 20 THE COST OF ADAPTING TO CLIMATE EXTREMES IN BANGLADESH By 2050, an estimated US$3.3 billion will be estimates for this infrastructure provide a lower required to protect roads, railways, river bound on the actual costs of adaptation, as they embankments, and drainage infrastructure do not include the additional adaptation required against the added inundation from inland in urban areas and for currently unprotected monsoon floods due to climate change. For the river banks (Table 3.5). climate change scenario considered, the itemized Table 3.5 Total adaptation cost for inland monsoon floods Cost component Investment (million US$) Road height enhancement 2,718 Road cross-drainage 5 Railway height enhancement 27 River embankment enhancement 96 Cross-drainage of coastal polders 421 Total cost 3,267 More than 83 percent of the total adaptation cost is for raising the height of the road network. Additional drainage structures in coastal areas account for another 13 percent of costs, while the remaining measures account for less than 4 percent of the total adaptation cost. 4 21 Chapter Added Inundation from Cyclones in a Changing Climate Cyclones pose a threat to lives and properties of 2007; Hansen and Sato 2011). The IPCC further low-lying coastal regions in Bangladesh. Nearly indicates that future cyclonic storm surges and every year, cyclones hit the country's coastal related coastal floods in Bangladesh will likely region and a severe cyclone strikes the country become more severe as future tropical cyclones every three years, on average. In a changing increase in intensity (IPCC 2007). A study using climate, increase in ocean surface temperature dynamic, Regional Climate Model (RCM)-driven and rising sea levels are likely to intensify cyclonic simulations of current and future climates storm surges and further increase the depth and indicates a significant increase in the frequency of extent of storm surge-induced coastal inundation highest storm surges for the Bay of Bengal, in Bangladesh. despite no substantial change in the frequency of cyclones (Unnikrishnan et al. 2006). Emanuel This study integrated information on climate projects increased intensity of tropical storms by change, hydrodynamic models, and geographic 2100 for the North Indian Ocean, as measured overlays to assess the vulnerability of coastal by the percent change in landfall power using the areas in Bangladesh to larger storm surges and MIROC (United Nations and World Bank 2010). sea-level by 2050. The focus of this study was on Surges will be further elevated by a rising sea cyclones with 10 percent or greater probability level as thermal expansion and ice cap(s) of occurring each year.1 This chapter briefly continue to melt (Nicholls et al. 2007; Dasgupta reviews scientific evidence to date on cyclone et al. 2010b). forecasts, and then details the potential inundation zones and depths and populations at Larger storm surges threaten greater future added risk from storm surges in a changing destruction, because they will increase the depth climate. of inundation and will move further inland, threatening larger areas than in the past. The Added risk of climate change destructive impact of storm surges will generally The available scientific evidence indicates that be greater when surges are accompanied by increased sea-surface temperature with climate strong winds and large onshore waves. This change will intensify cyclone activity in the tropics scientific evidence points to the need for greater and heighten storm surges (IWTC 2006; IPCC disaster preparedness in coastal Bangladesh. 1 The study analysis did not address the likely problem of salinity intrusion that a rise in sea level and intensified cyclonic storm surges might induce. 22 THE COST OF ADAPTING TO CLIMATE EXTREMES IN BANGLADESH Figure 4.1 Tracks of major cyclones in 1960-2009 spannedBangladesh's entire coastline. Source: IWM Changes in potential storm-surge zones Bengal up to 160 latitude.3 The resulting and depths due to climate change inundation map is based on the maximum level To assess the impact of climate change on of inundation at all grid points of the model. cyclone-induced storm surges, this study first To approximate cyclones in a changing climate demarcated the potential inundation zone and by 2050, this analysis considered a sea-level rise of projected depth of inundation for both a baseline 27 cm (UK DEFRA 2007), increased wind speed scenario without climate change and one with of 10 percent (World Bank 2010), and landfall climate change. Under the baseline scenario, during high tide.4 The scenario with climate change tracks of the 19 major cyclones that made used the tracks of the same 19 historical cyclones landfall from 1960 to 2009 were used, along with and the affected coastal regions to simulate their corresponding observed wind and pressure potential tracks out to 2050. The overlapping fields (Figure 4.1).2 These historic cyclones tracks of the 1974, 1988, 1991, and 2007 cyclone formed the basis against which future climate tracks covered the Sundarban coast, southwestern change risk was measured. coast (Sundarban to Patuakhali), Bhola and The inundation effect of storm surges was Noakhali coast in the Meghna Estuary, and eastern assessed using the two-dimensional Bay of Bengal coast (Sitakunda to Banshkhali); an artificial track Model, recently upgraded and updated under the was generated to cover the Sandwip coast and Comprehensive Disaster Management Program parts of the Noakhali and Chittagong coasts in the of Bangladesh (UK DEFRA 2007). The model is central part of the Meghna Estuary. Together, these based on the MIKE 21 hydrodynamic modeling five tracks were used to determine the inundation system, and its domain covers the coastal region zones due to climate change-induced storm of Bangladesh up to Chandpur and the Bay of surges (Figure 4.2). 2 See Dasgupta et al., Vulnerability of Bangladesh to Cyclones in a Changing Climate: Potential Damages and Adaptation Cost, Appendix 3. World Bank, Washington, DC (2010b). 3 Ibid., Appendix 1. 4 Scientific evidence to date suggests that the intensity of cyclones in the Bay of Bengal will increase in frequency; thus, the probability of potential landfall during high tide will also rise. CHAPTER 4 : ADDED INUNDATION FROM CYCLONES IN A CHANGING CLIMATE 23 Figure 4.2 Five cyclone tracks span Bangladesh's entire coastline under the climate-change scenario. Note: The meteorological parameters of Cyclone Sidr were used to demarcate the artificial track To determine potential future inundation intensification of cyclone-induced inundation, zones by 2050 under the climate-change inundation maps for 2050 were generated, again scenario, the storm-surge model was run for the applying the Bay of Bengal model. Results five cyclone tracks (covering the entire coastal showed that, under the climate-change scenario, area), incorporating a 27-cm rise in sea level, a the areas vulnerable to inundation depths of 10-percent increase in wind speed, and landfall of more than 1 m and 3 m, respectively, would be cyclones during high tide. Based on the 14 and 69 percent higher than under the simulation results, which accounted for potential baseline scenario (Figure 4.3). Figure 4.3 High risk area by 2050 in a changing climate (Source: IWM) 24 THE COST OF ADAPTING TO CLIMATE EXTREMES IN BANGLADESH Inundation Baseline Climate-change depth (m) scenario (km2) scenario (km2) Change (%) >1 20,876 23,764 +14 3 10,163 17,193 +69 In addition, it is estimated that a 10-year-return- Currently, 8.06 million people in coastal period cyclone in a changing (2050) climate will Bangladesh are vulnerable to inundation depths be more intense and cover 43 percent of the greater than 3 m resulting from cyclonic storm vulnerable area, 17 percent more than the surges. With population growth, that number is current coverage. 5 projected to increase to 13.5 million by 2050 under the baseline scenario. Without further Coastal population at risk adaptation measures, another 9.1 million coastal GIS software was used to estimate the inhabitants will be exposed to similar inundation population exposed to inundation risk from risk by 2050 under the climate-change scenario. cyclones and associated storm surges by 2050 The population exposed to 1-3m inundation under the two scenarios.6 depth is expected to increase by 7.06 million due to climate change (Table 4.1). Table 4.1 Vulnerable population estimates for cyclonic storm surges Inundation Current 2050 under Change (%) 2050 under Change (%) depth (m) baseline between climate- between scenario current and change baseline and baseline scenario climate- change scenario scenarios in 2050 >1 16.83 28.27 + 68 35.33 + 25 >3 8.06 13.54 + 68 22.64 + 67 As a cautionary note, it should be noted that this analysis did not address the out-migration from coastal zones that a rise in sea level and intensified cyclonic storm surges might induce. 5 The study did not attempt to estimate the location-specific probability of 10-year-return-period cyclones. 6 Since the values of the pixels in population surfaces represented numbers of people, the exposure was calculated by multiplying the exposure surface by the inundation zone and then summing by multiplying grid count and value. The computation used population density at the thana level. 5 25 Chapter Adaptation Cost: Cyclones Bangladesh is highly prone to cyclones. Since the Infrastructure at added risk of storm- 1960s, the government has invested $10 billion surge inundation due to climate change on polders, cyclone shelters, and emergency To identify the infrastructure exposed to added warning and awareness-raising systems to inundation risk, GIS software was used to overlay protect low-lying coastal areas. These protective the best available, spatially-disaggregated data on measures have significantly reduced cyclone- polders, cyclone shelters, and other infrastructure related loss of life and property damage over in the country's coastal zone, with projected time. However, in a changing climate, the greater inundation zones and inundation depths for 2050 expanse and depth of cyclone-induced storm under the baseline and climate-change scenarios.1 surges may exceed the capacity of the country's For each exposure indicator, estimates were protective coastal infrastructure and current level calculated by overlaying the inundation zone with of disaster preparedness. the appropriate exposure-surface data set. For the Based on the inundation area and vulnerable exposure grid surfaces, three GIS models were population estimates presented in the previous built to calculate the exposed value. The exposure chapter, this study assessed gaps in protective indicators, including land surface, agriculture extent, coastal infrastructure and quantified the road infrastructure, and railways, were measured in adaptation cost to more intensified 10-year- square kilometers or kilometers. The exposure return-period cyclones out to the year 2050. To estimates of other impact elements (e.g., cyclone itemize the adaptation-cost estimates, the study shelters) were counts. started with the identification of the critical The next sections present itemized estimates infrastructure exposed to the added risk of of adaptation measures, including height storm-surge inundation in a changing climate. enhancement of coastal polders, afforestation to This chapter first presents how critical protect sea-facing polders, multipurpose cyclone infrastructure at added risk of storm surge- shelters, cyclone-resistant private housing, and induced inundation were identified and then strengthening of the early warning and provides the total and itemized adaptation cost evacuation system. All estimates are indicated in estimates. 2009 prices. 1 Exposure surface data were collected from the public sources noted in footnote 1 (chapter 3). 26 THE COST OF ADAPTING TO CLIMATE EXTREMES IN BANGLADESH Figure 5.1 In a changing climate, 33 sea-facing and 26 interior polders will likely be overtopped by 2050. Source: IWM Height enhancement of coastal polders polders and 33 sea-facing coastal polders will be In the 1960s and 1970s, 123 polders, 49 of which overtopped (Figure 5.1). are sea-facing, were constructed to protect The study computed the cost of enhancing Bangladesh's low-lying coastal areas against tidal the height of the polders identified as likely to be floods and salinity intrusion.2 To identify which overtopped. The amount of needed earthwork polders will likely be overtopped by intensified was determined from engineering designs, and storm surges and the extent of that overtopping, the current local prices for ear thwork, the study computed differences between the compaction, and turfing were provided by the crest level of embankment for each polder and BWDB.3 The cost of required hard protection of the inundation depths projected for 2050 under some polder sections was computed using the the baseline and climate-change scenarios. rate for the highest ranked, locally available The results indicate that by 2050, under the technology (i.e., cement concrete blocks with baseline scenario, 14 interior polders and 30 sea- sand filters and geo-textile). The cost of facing polders will be overtopped; under the compensating private landowners for the climate-change scenario, an additional 26 interior additional land needed to strengthen the bases 2 The BWDB maintains an extensive database on coastal polders, including data on their length, location, construction year, and cost. 3 See Dasgupta et al., Vulnerability of Bangladesh to Cyclones in a Changing Climate: Potential Damages and Adaptation Cost, Appendix 4. World Bank, Washington, DC (2010b). CHAPTER 5 : ADAPTATION COST: CYCLONES 27 Table 5.1 Estimated cost of enhancing height of coastal embankments (million US$) Polder Baseline Climate change Additional cost type scenario scenario due to climate change Interior 317 706 389 Sea-facing 2,145 2,648 503 Total 2,462 3,354 892 of the height-enhanced polders in interior or width protective forest belt, a foreshore area of marginal areas was also estimated. Maintenance 448.5 km2 (897 km x 0.5 km) would require cost was assumed to represent 2 percent of afforestation. At the current cost of US$168,000 capital investment. Under the baseline scenario, per km2, the projected cost would total US$75 the adaptation costs total $2.46 billion. In a million. changing climate, the additional adaptation cost totals US$892 million (Table 5.1).4 Multipurpose cyclone shelters In Bangladesh, cyclone shelters are critical for Afforestation protection of sea-facing protecting human lives and livestock. During polders Cyclone Sidr in 2007, for example, 15 percent of In the past, foreshore afforestation schemes have the affected population took refuge in cyclone proven cost effective in dissipating wave energy shelters, which were estimated to have saved and reducing hydraulic load on embankments thousands of lives (Figure 5.2). Yet many existing during storm surges.5 Currently, however, cyclone shelters are in dilapidated condition and Bangladesh has insufficient foreshore forests. Of fail to provide for the special needs of women, the 957-km total length of embankment of 49 people with disabilities, and provision for sea-facing polders, there are only 60 km of forest livestock. belts, much of which is degraded. The Department of Forests and IWM recommend a Though the need for cyclone shelters is minimum of 500-m width mangrove forest to expected to decline if polders are raised protect sea-facing polders. sufficiently and properly maintained, shelters will still be needed to protect inhabitants of smaller To compute the gap between the islands, where polder protection may not be recommended 500-m width mangroves and cost effective; people living in areas with existing area-specific ones, this study estimated projected inundation depths greater than 3 m; the current length of coastal afforestation and residents living in one-story houses. Current between the coastline and polders using consensus favors multipurpose cyclone shelters Google Earth and GIS methodology. The results with elevated space for livestock and overhead indicate that 897 km length of existing sea water storage that can also serve as a primary facing polders would require mangrove forests school or office space in non-emergency times. for protection. For the recommended 500-m 4 Ibid., Appendix 5. 5 Such benefits were evident in Cyclone Sidr (2007) and Cyclone Aila (2009). An in-depth study of the damages and losses from Cyclone Sidr noted that even scattered, unplanned forestation along the foreshore of the embankments substantially reduced the velocity of storm surges (GOB 2008). 28 THE COST OF ADAPTING TO CLIMATE EXTREMES IN BANGLADESH Figure 5.2 Spatial locations of existing cyclone shelters in coastal areas Source: CEGIS Vulnerable-population estimates presented in the 2008). In coastal regions, houses can be made previous chapter indicate that 9.1 million cyclone-resistant by following suitable designs inhabitants will be exposed to storm surge- and building codes. This study analysis, which induced inundation depths of more than 3 m included consultations with local architects and due to climate change by 2050. Accommodating civil engineers, recommends encouraging the these additional people will require adding about construction of brick-built houses with concrete 5,700 multipurpose cyclone shelters, at an roofs (on stilts, if needed), in accordance with estimated cost of US$1.2 billion.6 appropriate building codes. These houses could serve as single or multi-family cyclone shelters Cyclone-resistant private housing during storm surges. The subsidized construction In the past, the housing sector has accounted for material and housing credit would require setting a significant portion of cyclone damage. For up a revolving fund in the amount of US$200 example, in 2007, it accounted for half of the million.7 economic damage caused by Cyclone Sidr (GOB 6 To estimate the costing of multipurpose cyclone shelters, current cyclone-shelter costs and capacity were collected from World Bank-funded projects. The current cost of a shelter to accommodate 1,600 people is US$214,000. 7 Subsidies must be designed with caution to avoid misuse. CHAPTER 5 : ADAPTATION COST: CYCLONES 29 Strengthened early warning and On further infrastructure investment evacuation system The strong structural-protection measures Bangladesh's early cyclone warning and considered in this analysis (i.e., polders) reduced evacuation system is vital to saving lives. The the need to raise the resilience of such overall quality of cyclone and storm-surge infrastructure as roads and bridges to storm forecasting has improved in recent years; surges, except in regions or islands without however, the general consensus is that further current or anticipated polder protection. improvements are needed. These include the need for greater precision in forecasting, Cost of added inundation from cyclones especially with regard to landfall location and and related storm surges location-specific inundation depth; broadcasting Despite the extensive infrastructure Bangladesh of warnings in local dialects; and raising has in place to protect coastal residents from awareness to promote timely and appropriate cyclonic storm surges and tidal waves, geographic evacuation.8 overlays of inundation depth under the baseline The estimated costs of the surveys and (without climate-change scenario) reveal that mathematical modeling required to improve currently 44 of the country's 123 coastal polders projections for location-specific inundation, as run the risk of overtopping if a severe cyclone recommended by the IWM, total US$8 million. hits. As a result, the country has an outstanding Modernization of the Bangladesh adaptation deficit of US$2.46 billion, making it Meteorological Department (BMD) (setting up more difficult to fully climate-proof infrastructure. additional observatories and upgrading existing In a changing climate, the greater expanse and ones, establishing radiosonde stations, depth of the areas inundated will put many more modernizing workshop and laboratory, and existing structures at risk. Geographic overlays of developing training institute facilities) totals inundation depth under the climate-change US$30 million. Operation and maintenance scenario indicated another 59 coastal polders will costs of existing and additional observatories be over topped by 2050, and inadequate are estimated at US$5 million annually, while the mangrove forests will mean higher-velocity storm awareness-raising promotion program surges. Moreover, the capacity of life-saving recommended by the Red Crescent Society cyclone shelters and early warning and totals US$3 million per year. evacuation systems will be exceeded. 8 The study team conducted focus group interviews with experts at the IWM, BMD, Red Crescent Society, and residents of recent cyclone-affected areas on their recommendations for strengthening the early warning and evacuation system. 30 THE COST OF ADAPTING TO CLIMATE EXTREMES IN BANGLADESH Table 5.2 Total adaptation cost for cyclones and associated storm surges by 2050 Baseline Additional cost scenario with climate change Investment Investment Annual recurrent cost Measure (million US$) (million US$) (million US$) Polders 2,462 892 18 Foreshore afforestation 75 Multipurpose cyclone shelters 1,200 24 Cyclone-resistant private housing 200 Strengthening of early warning system 39 8+ Total 2,462 2,407 50 + By 2050, the total additional investment needed to cope with a changing climate will total about US$2.4 billion, with an annual recurrent cost of more than US$50 million (Table 5.2). The costing of adaptation refers to the increased inundation area and depth for a 10-year return cyclone in a changing climate. 6 31 Chapter Toward Adaptation and Investment Planning As indicated in the previous chapters, in the assessments for the two climate hazards coming decades, Bangladesh is likely to analyzed, totaling US$5.7 billion, are conservative, experience heavier, more erratic monsoon and do not include the added adaptation flooding of greater inundation depth, extent, and required for urban areas, unprotected river duration, as well as higher-intensity cyclonic banks, and salinity intrusion. As mentioned storm surges with potentials to ravage further previously, the country currently has a significant inland. The area vulnerable to inland monsoon climate-adaptation deficit,2 making it more inundation will rise by 4 percent, and the entire difficult to determine the full cost of climate- area at risk (nearly half of the country) is proofing infrastructure. expected to encounter higher inundation depths due to climate change. The coastal area Given the large uncertainties about the vulnerable to storm surge-induced inundation magnitude and timing of added risks from climate with a depth of more than 3 m will rise by about change, sequencing of adaptation actions is a 69 percent by 2050, suggesting that a single necessity, particularly in a fiscally constrained cyclone with a 10-year return period will cause environment. The itemized adaptation-cost significantly more damage (Appendix). estimates presented in this report can serve as a tool to enable decision makers in Bangladesh to In a changing climate, the greater expanse and prioritize and sequence adaptation actions and depth of the areas affected by inland monsoon investments, as resources permit. Recognizing the floods and tropical cyclones will put the uncertainties in the timing and magnitude of the population, assets, and economic activities at impacts of climate change, a prudent strategy fur ther risk. This study's itemized cost would begin by addressing existing risks that assessments indicate that, at 2009 prices, the current residents face. Existing investments, which total cost of adaptation to offset the added have reduced the impacts of floods and cyclones, inundation from climate change is estimated at provide a solid foundation upon which additional US$3.3 billion for inland monsoon flood measures to reduce potential damages now and protection infrastructure and US$2.4 billion for in the future may be undertaken to minimize the storm-surge protection by 2050.1 These cost climate risks. 1 The estimated damage from a single 10-year-return-period cyclone, compared to the cost of storm-surge protection, indicates that the incremental cost of adapting to climate change by 2050 is small compared to the potential damage, which strengthens the case for rapid adaptation (Appendix); this comparison is conservative, given that the damage from more frequent, but less intense, cyclones has not been considered. 2 Hence, there exist substantial risks from severe flooding, even in the current climate. 32 THE COST OF ADAPTING TO CLIMATE EXTREMES IN BANGLADESH The evaluation of infrastructure investments effects in the least disruptive way without placing conducted in this study has been done within a a disproportionate burden on the poor and framework of appropriate development policies vulnerable. and efficient institutional arrangements. Taken alone, these "hard" adaptation investments By 2050, the number of people living in urban cannot yield the expected benefits. Indeed, areas is expected to triple, while the rural sound public policies, planning, and institutions population will decline by nearly a third. Current are the foundation for ensuring that more government policies will determine where this capital-intensive measures are wisely urban population will settle and how well implemented. Design of flood embankments, prepared it will be to adapt to a changed for example, must be carefully considered since climate. Many households have already moved their construction is usually followed by the fur ther inland and are adopting positive accumulation of physical capital behind the incentives to promote settlements and urban barriers, which are considered "safe." Flood growth in low-risk areas. Sound policies that embankments must be strengthened beyond promote increased access to education and their current protective capacity as the added appropriate job training will better prepare risk of inundation becomes more certain. It is future rural populations for productive urban also critical to develop appropriate design lives and thus avoid perverse incentives to standards commensurate with likely climate remain in high-risk coastal areas. risks over the expected lives of assets and Coping with climate change over the longer update them as new research becomes term will also require strengthened cooperation available. among neighboring countries in the GBM basin. It should also be taken into account that physical An effective strategy must include the measures may not reduce human suffering and development of institutions and mechanisms for asset damages and losses as much as expected in transboundary negotiations on the sharing of the long run. These "hard" investments must be water resources. This is not a new issue, but one complemented by education, job training, and whose importance may be amplified by climate other "soft" investments designed to reduce change. As the stakes rise, taking steps now to reliance on resources and assets whose value promote and strengthen cooperative may be eroded by climate change. In short, management of shared resources can not only adaptation planning should not attempt to resist offer all parties immediate benefits. It can also the impact of climate change. Rather, it should prevent the need for more expensive, disruptive offer a sustainable path that accommodates its solutions in the future. REFERENCES 33 References Ahmed, A. U., and M. Alam. 1998. "Development of Climate Change Scenarios with General Circulation Models." In Vulnerability and Adaptation to Climate Change for Bangladesh, eds. S. Huq, Z. Karim, M. Asaduzzaman, and F. Mahtab, 13-20. Dordrecht: Kluwer Academic Publishers. 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"Global Warming and Changes in the Probability of Occurrence of Floods in Bangladesh and Implications." Global Environmental Change 12: 127-38. Mirza, M. M. Q., and A. Dixit. 1997. "Climate Change and Water Resources in the GBM Basins." Water Nepal 5(1): 71-100. Mirza, M. Q., R. A. Warrick, N. J. Ericksen, and G. J. Kenny. 1998. "Trends and Persistence in Precipitation in the Ganges, Brahmaputra and Meghna Basins in South Asia." Hydrological Sciences Journal 43(6): 845-58. Murty, T.S., and M. I. El-Sabh. 1992. "Mitigating the Effects of Storm Surges Generated by Tropical Cyclones: A Proposal." Natural Hazards 6(3): 251-73. REFERENCES 35 Nicholls, R. J., S. Hanson, C. Herweijer, N. Patmore, S. Hallegatte, J. Corfee-Morlot, J. Chateau, R. Muir- Wood. 2007. Ranking Port Cities with High Exposure and Vulnerability to Climate Extremes. OECD Environment Directorate, Environment Working Papers No. 1. Paris: Organisation for Economic Co-operation and Development. Qureshi, A., and D. Hobbie. 1994. Climate Change in Asia. Manila: Asian Development Bank. Siddiqui, K. U., and A. N. H. A. Hossain (eds.). 2006. Options for Flood Risk and Damage Reduction in Bangladesh. Dhaka: University Press Limited. SMRC (SAARC Meteorological Research Centre). 2000. The Vulnerability Assessment of the SAARC Coastal Region Due to Sea Level Rise: Bangladesh Case. Dhaka: SMRC. UK DEFRA (Department for Environment, Food and Rural Affairs). 2007. Investigating the Impact of Relative Sea-level Rise on Coastal Communities and Their Livelihoods in Bangladesh. London: UK DEFRA. UNDP (United Nations Development Programme). 2004. A Global Report: Reducing Disaster Risk: A Challenge for Development. New York: UNDP Bureau for Crisis Prevention and Recovery. Available at www.undp.org/bcpr. United Nations and World Bank. forthcoming. UnNatural Disasters: The Economics of Reducing Death and Destruction. Unnikrishnan, A. S., R. Kumar, S. E. Fernandez, G. S. Michael, and S. K. Patwardhan. 2006. 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London: Earthscan Publishers. 37 Appendix Impact of a 10-year-return-period Cyclone in Bangladesh by 2050 This study also estimated the damage from a 10- assets, while losses refer to the potential flow of year-return-period cyclone and associated storm goods and services not provided and the surges by 2050. Exposure of critical impact increased costs of continuing essential services. elements using geographical overlays formed the The sections below estimate the potential human basis for estimating the potential damages and casualties and injuries from such a cyclone and losses for the baseline and climate-change their estimated economic damage, and the scenarios. The assessment also drew on potential damage to sectors that experienced projected annual growth in Bangladesh's coastal high monetary damage and losses from Cyclone population (1 percent) and GDP (6-8 percent) Sidr in 2007 (housing, education, agriculture, non- and the devastation (US$1.67 billion damages agricultural productivity, roads, power, and and losses) experienced in 2007 resulting from protective coastal infrastructure). Cyclone Sidr. Human casualties and injuries Based on major cyclone events from 1876 to 2009, it is estimated that a cyclone like Sidr (with In 2007, storm-surge inundation from Cyclone wind speed of 223 km per hour) has a 10-year Sidr affected some 3.45 million residents in return period. In calculating damages, the study Bangladesh's coastal areas. Cyclone shelters adjusted for the greater extent of storm-surge saved thousands of lives, yet 3,406 people died inundation (area with an inundation depth of 1 m and 55,282 more were injured, according to or more) from Cyclone Sidr, which was 8.7 post-disaster assessments. Focus-group percent more than the historical average interviews with affected residents revealed that a inundation area of a 10-year return cyclone in large proportion of the population was reluctant Bangladesh. It is estimated that future 10-year- to move to cyclone shelters, even during an return-period cyclones will cover 17 percent emergency. The primary reasons cited for this more vulnerable area than the current average. reluctance were distance from the homestead, All estimates were adjusted for 2009 price levels, difficult access to shelters, unwillingness to leave in accordance with the 18-percent increase in unprotected livestock behind, scarcity of the GDP deflator in 2007 and 2009. sanitation facilities, lack of user-friendly facilities for women, and overcrowding. Population and infrastructure at added Assuming that Bangladesh attains a risk of storm-surge inundation due to replacement fertility rate by 2021 and 1-percent climate change average annual growth in coastal population In this analysis, damages refer to the potential between 2001 and 2050, the number of people complete or partial destruction inflicted on exposed to the risk of storm-surge inundation 38 THE COST OF ADAPTING TO CLIMATE EXTREMES IN BANGLADESH from a 10-year-return-period cyclone by 2050 Bangladesh ($4.86) (Cropper and Sahin 2009). would total 5.34 million under the baseline This yields a total economic damage from scenario and 10.04 million with climate change. increased injury risk of US$0.352 million; Without improved infrastructure protection in a however, this estimate does not include any value changing climate, extrapolation with the ratios of of lost production and income from injury or the casualty (0.001) and injury (0.016) to exposure more subjective losses of well-being resulting experienced in 2007 indicates a risk by 2050 of from injury or incapacitation. 4,637 additional human casualties and 75,268 more injuries.1 Housing It is enormously difficult to attach a In 2007, the housing sector was hardest hit by monetary-equivalent value to these risks that can Cyclone Sidr. The types of houses damaged be combined with and compared to the risks of were predominantly semi-pucka, kacha, and financial damage and loss. The most appropriate jhupris.3 Analysis of Bangladesh's 2001 census measure of the benefit from reduced risk of data indicates that only 2.23 percent of rural fatality is the Value of Statistical Life (VSL), which households with an annual income of US$470 estimates the monetary equivalent of improved per capita (Tk. 2,750 per capita per month) or well-being for individuals from reduced risk of higher could afford a brick house with a concrete mortality. In reality, VSL should reflect the context roof (i.e., pucka house). But it is expected that, of the risk; for example, the risk of sudden fatality by 2050, the vast majority (about 98 percent) of from an accident would differ from that of households will live in brick houses, suggesting a reduced future life span from long-term pollutant significant reduction in housing damage but a exposure. substantial rise in household asset damage from cyclones over time (BBS 2007). This analysis used a VSL estimate of Tk. 15.5 million (about US$0.2 million) for Bangladesh.2 In a changing climate, it is projected that an Multiplying this figure by the expected value of additional 1.45 million houses (assuming an the increased number of lives at risk from a 10- average family size of 4.89) will be exposed to year-return-period cyclone in a changing climate significant damage from storm surges by 2050. A results in US$1.03 billion of additional economic 10-year-return-period cyclone, with a larger damage from greater fatality risk. extent of inundated area, would be expected to damage another 1.6 million houses. The assumed To calculate the economic damages from size of a standard house is 400 ft2, with 2,000 ft2 increased risk of injury, this study adopted a of brick wall surface and US$2,143 (Tk. 150,000) crude lower-bound estimate, based on the World of household assets. Assuming that half of all Health Organization figure for cost per walls and household assets were damaged, outpatient visit at a secondary hospital in replastering of houses would cost US$229 1 In the baseline scenario, by 2050 a 10-year-return-period cyclone would cause an estimated 5,274 casualties and 85,609 injuries; under the climate-change scenario, those estimates would rise to 9,911 and 160,877, respectively. 2 This estimate was computed by updating the central estimate of the VSL for the United States (US$7.4 million in 2006 dollars) available from the US Environmental Protection Agency with a price adjustment between 2006 and 2008 and a GDP differential between the United States and Bangladesh. 3 Semi-pucka houses have foundations made of earthern plinth or brick and concrete, bamboo-mat walls, and roofs made of CI sheet with timber framing. Kacha houses have foundations made of earthern plinth, bamboo walls made of organic materials, and thatched roofs made of straw and split bamboo. Jhupris houses have ceilings made of various inexpensive materials (e.g., straw, bamboo, grass, leaves, polythene, gunny bags). APPENDIX : TOWARD ADAPTATION AND INVESTMENT PLANNING 39 million (at Tk. 10 per square foot) and asset cyclone in the post-monsoon season than in damages about US$1.718 million. the pre-monsoon season (67 percent versus 33 percent). The resulting difference in risk exposure Education infrastructure for the three major rice crops was accounted for Given that, by 2050, an additional 7.08 million in the damage estimations. Assuming a 2.4- coastal residents would be exposed to storm percent annual growth rate for cereal surges caused by climate change, 456,690 production, observed during 2001-07, a 10-year- primary school students (2,283 primary schools) return-period cyclone would damage 50 percent and 312,957 secondary school students (2,086 of yield, resulting in US$788.83 million of secondary schools) would be at risk. Accounting additional damage caused by climate change by for the larger extent of inundation area from a 2050. 10-year-return-period cyclone, an additional In 2007, Cyclone Sidr caused damages and 4,840 primary and secondary schools would be losses of US$19.3 million and US$6.7 million to damaged. A standard school in Bangladesh is livestock and fisheries, respectively. Assuming about 160 m2 and its contents worth US$2,857 annual growth rates of 3 and 6 percent, (Tk. 200,000). Assuming that half of the school observed during 2001-07, the additional damage walls and contents would be damaged during from a 10-year-return-period cyclone with inundation, the estimated damage would total climate change would total about US$55.62 US$8.96 million, and the cost of making million and US$66.36 million, respectively. alternative arrangements during the repair of facilities would be US$0.82 million. Non-agricultural productivity Agriculture In 2007, Cyclone Sidr inflicted US$51.4 million in damages to Bangladesh's non-agricultural The study analysis computed the potential productive sectors, with storm-surge inundation damage and loss to crop production, livestock, covering 558,512 ha. That year, these sectors and fisheries. Cereal production was limited to (including small- and medium-sized enterprises, Table A-1 Cost (US$) to enhance height of coastal embankments Polder type Baseline scenario Added cost with climate change Sea-facing 317 million 389 million Interior 2.145 billion 503 million aman (monsoon), aus (pre-monsoon), and boro commerce, and tourism) accounted for more (post-monsoon) rice. With the expanded area of than four-fifths of the country's GDP (World storm-surge inundation expected with climate Bank 2009); by 2050, their share of GDP is likely change, these crops are expected to incur to grow by another 11 percent.4 In a changing significant damage (Table A-1). climate, a 10-year-return-period cyclone is Historical records show that Bangladesh is estimated to damage more than 1 million ha, about twice as likely to be hit by a tropical representing an additional potential damage of US$87.9 million. 4 Between 2007 and 2050, Bangladesh's GDP is expected to increase 21.48 times. 40 THE COST OF ADAPTING TO CLIMATE EXTREMES IN BANGLADESH Road infrastructure a similar per capita income, Bangladesh's power Past experience suggests that roads are partially infrastructure is expected to increase 5 times and damaged when the depth of surge inundation is its per capita power consumption 20 times by less than 1 m and fully damaged above 1 m. 2050. Based on the damages from Cyclone Sidr, Assuming a 25-percent growth in the country's combined with the projected growth in power road network from 2005 to 2050, the study infrastructure, potential damages under the analysis indicates that, under the baseline baseline scenario would cost US$239.1 million scenario, 3,998 km of roads would be exposed and US$449.3 million under the climate-change to an inundation depth of less than 1 m and scenario. The additional inundation damage from 8,972 km exposed to a depth above 1 m by a 10-year-return-period cyclone would total 2050. With climate change, those figures would US$60.2 million in a changing climate. rise to 10,466 and 10,553, respectively. Accounting for the larger extent of inundated Protective coastal infrastructure area from a 10-year- return-period cyclone, an Storm-surge over topping of polder additional 3,461 km of roads would be partially embankments, the key reason for polder damage, damaged and 2,205 km fully damaged under the causes rapid and deep scours to form on the climate-change scenario. Based on the post- country-side slope of the embankment; the assessment damages from Cyclone Sidr in 2007, process rapidly weakens the structure, leading to the additional damage to roads, bridges, culverts, its collapse. In 2007, Cyclone Sidr caused and related infrastructure in a changing climate US$70.3 million in damages to Bangladesh's would total US$239.5 million. coastal polders and related water regulators. A comparison of projected surge heights with Power infrastructure heights of existing polder embankments indicates Damage from Cyclone Sidr in 2007 to that, by 2050, an additional 15 polders will likely Bangladesh's coastal power sector totaled be overtopped by cyclonic storm surges in a US$8.2 million. Given the coastal area's projected changing climate, with an estimated additional population growth between 2007 and 2050 and US$17.3 million in damages. projected power consumption in countries with CHAPTER 5 : ADAPTATION COST: CYCLONES 41 Cost of added inundation from a 10-year-return-period cyclone Table A-2 Added potential damage and loss from an average cyclone-induced inundation in a changing climate by 2050 ($2009 prices) Infrastructure/ Damage estimate Loss estimate sector asset (million US$) (million US$) Housing 1,947.3 0.8 Education 9.0 835.4 Agriculture 75.4 1,084.0 Non-agricultural productivity 87.9 52.7 Roads 239.5 150.0 Power 60.2 Coastal protection 17.3 Total 2,436.6 2,122.9 Damage refers to partial or complete destruction of assets Loss refers to the loss in the flow of goods and services The total additional potential damage from a 10-year-return-period cyclone in a changing climate is estimated at US$2.44 billion, with US$2.12 billion in added potential losses (Table A2).