Climate risks and adaptation in Asian coastal megacities: A synthesis

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mercial and industrial establishments, and majorpublic infrastructure). Flow damage included loss ofincome and increased morbidity, which are primarilylinked to the duration of a flood. The damageestimates were based on data extrapolated to theKMC population in 2050. The analysis assumed noadditional investments in flood protection measuresthat may be implemented in the future to lowerflood damage. Inflation also was not considered,and all estimates used 2009 prices. Damage assessmentswere estimated for the 100 year flood returnperiod and the A1FI climate change scenario todetermine the additional damage caused by climatechange effects.Adaptation analysisFinally, a separate analysis was done to examineadaptation measures in KMC that can alleviatesome of the problems posed by flooding. Theanalysis mainly focused on gains from the completede-siltation of trunk sewers by modeling floodingunder a completely de-silted trunk sewer scenario.The study also examined other proposals to buildnew sewers and upgrade sewers in vulnerable areas,as well as institutional changes that can help copewith future flood damage.Main FindingsThe most vulnerable wards to climate change. Thestudy identified the most vulnerable wards to climatechange—namely, wards14, 57, 58, 63, 66, 67,74, 80, and 108. Six wards (14, 57, 58, 66, 67, and108) in the eastern part of the city and ward 80 arevulnerable because of inadequate infrastructure,unplanned land use, and poor socioeconomic andenvironmental conditions. Infrastructural problemsare getting worse with increased building activity,as these areas have become attractive to developersafter becoming part of KMC.The other two wards—63 and 74—are highlyvulnerable due to their topography. In these wardsthe capacity of the sewerage system has not keptpace with changes in population. These have beenfurther aggravated by inadequate maintenance,as well as the siltation of the existing trunk sewersystems, which have considerably reduced their carryingcapacity. While the sewer networks in KMCunder such partially silted condition still providereasonable hydraulic capacity for carrying the dryweather flow, they are inadequate for carrying stormweather flow, even with normal precipitation duringthe rainy season.Additional losses likely to occur due to climatechange. Damage from a 100-year flood will increaseby about $800 million—to more than $6.8 billion in2050—due to climate change (A1FI scenario). Theimpacts by sector (in Indian rupees at 2009 prices)are shown in the chart below. Local currency wasconverted to dollars using the purchasing powerparity index for India of 2.88 (IMF 2009). The largestdamage components—under both the 100-yearreturn period flood and the A1FI climate changescenario—are for residential property and buildingsand health care. Commerce, industry, and otherinfrastructure like roads and transport services alsoTotal losses in major sectors in KMC (Rs million in 2050)40,00035,00030,00025,00020,00015,00010,0005,0000ResidentialbuildingResidentialpropertyResidentialincome lossCommerce Industry Healthcare Roads Transport ElectricityCurrent climate 100 year floodA1F1 climate 100 year flood88 | Climate Risks and Adaptation in Asian Coastal Megacities: A Synthesis Report
sustain significant damage. Due to data constraints,some impacts could not be quantified in this analysis,so the estimates provided are likely to understatethe overall impact of climate change.Investing in de-silting of trunk sewers willreduce the area and population affected by floods.The study looked at the impact of investing inde-silting trunk sewers both in the town andsuburban systems of KMC. The business as usualscenario considers an average 30 percent silting intrunk sewers. The adaptation scenario considersinvesting in de-silting and reducing it to zero. Thefindings indicate that this simple investment canreduce the area affected by a flood by 4 per centand the population affected by floods by at least5 percent.Adaptation MeasuresThe current adaptation deficit. Climate change islikely to intensify urban flooding through a combinationof more intense local precipitation, riverineflooding in the Hooghly, and coastal storm surgesA major cause of such periodic flooding during therainy season is the city’s current adaptation deficit,including deficiencies in physical infrastructure,problems with land use, and socioeconomic andenvironmental factors.Adaptation strategy. The city needs a comprehensiveand effective strategy that invests inboth soft and hard infrastructure to tackle floodingproblems in Kolkata. The goal of the strategy is to (a)reduce the percentage of people affected by floodingand sewage-related diseases in KMC, and (b)target the most vulnerable areas. The strategy shouldinclude preparedness both before and during theevent, as well as post-event rehabilitation strategies.Investing in hard infrastructure. Investing inhard infrastructure should take into account thefollowing:■■The strategy needs to follow a comprehensiveapproach to planning that recognizes drainagesystem complexity and interconnectivity of its elementssuch as storm water drainage, water supply,wastewater, water pollution control, waterreuse, soil erosion, and solid waste management.■■■■The strategy should protect major urban services,including roads, traffic, water supply, electricity,and telecommunications. It should recognizethe importance of open space and green areas asan integral part of city development.The strategy should spell out the climate risksand mitigating factors needed in operationalplans for key relevant agencies.Investing in soft infrastructure. To ensure longtermfinancial, institutional, and environmentalsustainability, the adaptation strategy should alsoinclude:■■■■■■■■■■■■■■Strengthening disaster management andpreparedness for both pre- and post-disastersituations.Enforcing land use and building codes to reduceobstruction and encroachment of floodplainsand environmentally sensitive areas such ascanal banks and wetlands and to prevent conversionof green spaces and natural areas thatcan act as retaining zones during flooding.Introducing sustainable financing—emphasizingboth cost reduction and cost recovery—forinfrastructure investment and maintenance.Increasing the budget for sewerage anddrainage maintenance and the allocation ofmoney for silt removal and mechanical sewercleaning.Adopting flood insurance that incorporates suitableincentives for adaptation and minimizesflood damage.Strengthening the regulatory and enforcementprocess, including improving institutional managementand accountability.Enforcing pollution management frameworks,including introduction of incentivesand disincentives to ensure compliance withregulations.The government of West Bengal has alreadystarted investing in adaptation. Among the suggestedadaptation measures, a number of projectsare either currently under way or are plannedfor future implementation in KMA under theJawaharlal Nehru National Urban Renewal Mission(JNNURM) and the KEIP scheme funded byVulnerability of Kolkata Metropolitan Area to increased Precipitation in a Changing Climate | 89
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© 2010 The International Bank for
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Figure 4.6 Damage Costs Associated
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AcknowledgmentsThis synthesis repor
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Executive SummaryIntroduction and R
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For each city, complex hydrometeoro
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infrastructure but a high emission
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these include strategies that focus
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policy implications have broader re
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2Methodologies forDownscaling, Hydr
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Table 2.1 ■ Climate Change Foreca
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Return periods considered 18In this
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Figure 2.2 ■ Manila Rainfall-Runo
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Figure 2.3 ■ Estimation of Damage
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sion and distribution lines, and en
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Figure 2.5 ■ Possible Relationshi
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prices and the same prices are appl
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3Estimating Flood Impactsand Vulner
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Table 3.2 ■ Bangkok Monthly Avera
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Estimation of storm surge in the ca
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Climate Change Impact and Adaptatio
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Figure 3.5a ■ Affected Condensed
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Manila’s current climate—Tropic
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Table 3.6 ■ Manila Climate Change
Page 57 and 58: Figure 3.10 ■ Areas of High Popul
Page 59 and 60: is also a key economic and financia
Page 61 and 62: Box 3.3 ■ HCMC in 2050Future land
Page 63 and 64: original swamp land on which the ci
Page 65 and 66: from 68 percent to 71 percent; that
Page 67 and 68: Table 3.15 ■ Districts Affected b
Page 69 and 70: Table 3.16 ■ Effects of Flooding
Page 71 and 72: 4Assessing Damage Costsand Prioriti
Page 73 and 74: Table 4.2 ■ Summary of Flood and
Page 75 and 76: uilt outside the cities and are not
Page 77 and 78: ■■■■■■For the eastern p
Page 79 and 80: Table 4.6 ■ Flood Damage Costs Wi
Page 81 and 82: Table 4.8 ■ Flood Damage Costs in
Page 83 and 84: Figure 4.5 ■ Loss Exceedance Curv
Page 85 and 86: Box 4.3 ■ Increased Time Costs an
Page 87 and 88: Table 4.11 ■ Adaptation Investmen
Page 89 and 90: Marikina River areas through a dam,
Page 91 and 92: Table 4.14 ■ Present Value of the
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Page 95 and 96: 5Conclusions andPolicy Implications
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Page 101 and 102: BibliographyAllen, M. R., and W. J.
Page 103: Reduction: Inventory and Prospect.
Page 106 and 107: a paper commissioned by JICA (Sugiy
Page 110 and 111: ADB. The selection and prioritizati
Page 113 and 114: AnnexCAdaptation to IncreasedFloodi
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Climate risks and adaptation in Asian coastal megacities: A synthesis

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