Climate risks and adaptation in Asian coastal megacities: A synthesis

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Table 3.9 ■ Affected Length of Road by Inundation DepthRoad Length by Inundation Depth (kms)8–20 cm 21–50 cm Above 50 cmFlood Scenario (Ex)Major Minor Major Minor Major MinorTotalStatus Quo 4.5 3.9 22.1 23.8 31.9 39.8 125.9B1 5.4 9.7 13.6 15.1 47.9 55.6 147.3A1FI 5.3 6.9 14.6 18.2 53.6 60.3 158.98–20 cmRoad Length by Inundation Depth (kms)21–50 cm Above 50 cmFlood Scenario (BAU)Major Minor Major Minor Major MinorTotalStatus Quo 3.78 4.33 6.40 10.45 7.45 13.42 45.82B1 7.24 8.15 9.54 15.73 12.07 20.82 73.55A1FI 9.45 9.05 12.62 16.28 14.97 25.63 87.99Source: Muto et al. (2010).Impact of existing flood-related events onthe poor 37In Metro Manila, there is a strong link betweenwhere the urban poor reside and their vulnerabilityto flooding. Interviews with 300 poor households(in 14 communities in three river basins) to assessthe impact of floods (conducted as part of theManila study) show that they primarily live inenvironmentally fragile, low-lying areas and/orswamps or wetlands that are highly vulnerable tostorm and tidal surges. Households interviewedhave a median monthly income of about 44 pesos/day (less than $1/day). Further, most of them livein slum or squatter settlements and do not havetenure security or access to basic services such asclean water, electricity, sanitation, and drainage.About two-thirds reported suffering regular lossesdue to typhoons, floods, and storm surges. Twentysevenpercent of the households interviewed havesubstandard latrines (dug latrines) or none at all(and use neighbor’s latrine or direct to the river/sea). Those who do have toilets complained abouttoilets overflowing and garbage being carried duringfloods contributing to waterborne diseases.About 65 percent of the households buy water fromneighbors or suppliers. During floods, householdexpenditures on water and transportation increase.Coping strategies include addition of stilts oradditional levels by households to escape risingflood waters, use of styrofoam boats, installationof pumps or “bombastic” to help drain flood water(done in some municipalities by the mayor).The survey details many of the public healthhazards associated with flooding . However, for someof the respondents, the consciousness of health risksposed by flooding is not very high. They say “Hindika naman namamatay dahil sa baha!” (You do notdie from floods or rising waters here!). For example,the risk of catching an infection like the deadly effectsof rat’s urine (i.e., leptospirosis) is not high intheir consciousness. Following Typhoon “Ondoy”in September 2009, however, there was an epidemicof leptospirosis that infected over 2,000 people, withover 160 people dying and many requiring dialysis.Estimating Climate-relatedImpacts in Ho Chi Minh City,VietnamHCMC is a tropical coastal city located on theestuary of the Saigon–Dong Nai River system ofVietnam. While not a capital city, Ho Chi Minh City37A detailed analysis of the impact of future flooding on thepoor was not undertaken as part of the Manila study andneeds to be carried out as a follow-up to this report.38 | Climate Risks and Adaptation in Asian Coastal Megacities: A Synthesis Report
is also a key economic and financial center and acore part of the Southern Economic Focal region inVietnam. The city’s official population is estimatedto be about 6.4 million people. The actual currentpopulation, which includes temporary and unregisteredmigrants, is estimated to be 7–8 million. Thepopulation of HCMC has been growing at a rateof 2.4 percent per year, which is a faster rate thananywhere else in the country. The city accounted forover 23 percent of the country’s GDP in 2006 (ADB2010). Rapid economic growth—11.3 percent annuallybetween 2000 and 2007—has been the centraldriver behind the city’s expansion, as the increasingnumber and magnitude of income earning opportunitiesattract migrants from throughout Vietnam.Key economic growth sectors include industrialand service sectors, which have grown at a rate of11.9 percent and 11.1 percent annually respectivelyTable 3.10 ■ HCMC District PovertyRates, 2003Urban districtsRural districtsPoverty RatePoverty RateDistrict(%) District(%)District 1 2.4 Cu Chi 6.9District 2 4.5 Hoc Mon 6.9District 3 2.8 Binh Chanh 4.4District 4 5.6 Nha Be 12.9District 5 3.8 Can Gio 23.4District 6 5.5District 7 3.0District 8 7.4District 9 5.0District 10 3.0District 11 4.6District 12 6.3Go Vap 6.9Tan Binh 5.5Binh Thanh 5.0Phu Nhuan 3.7Thu Duc 7.8HCMC average poverty rate 5.4Source: Inter-ministerial Poverty Mapping Task Force, 2003, cited in ADB (2010).between 2000 and 2007. During the same period, agricultureand related activities have grown relativelyslowly at a rate of 4.8 percent annually (ADB 2010).Nature of poverty in HCMCIn 2006, HCMC had an overall poverty rate of 0.5percent (GSO Vietnam 2006). 38 While this rate is thelowest in the country, the absolute number of poorin the city is still high at between 30,000 and 40,000persons. In addition, the number of households livingin inadequate housing and poor environmentalconditions is likely to be much higher than the officialpoverty rate suggests. If unregistered migrantsare primarily poor, then the poverty rate would alsobe higher due to the large numbers of migrants missingfrom official statistics. Spatially disaggregateddata for the city shows that there is significant variationin poverty levels in different parts of HCMC.In general, rural districts have higher poverty levelscompared to more urban districts. The highest povertylevels are in the relatively sparsely populatedrural districts of Can Gio and Nha Be to the southof the city toward the coast. These are also the twodistricts that are the most prone to flooding in thecity (Table 3.10).Climate and precipitation in the Dong NaiRiver BasinHCMC has a tropical monsoon climate with pronouncedwet and dry season variations in precipitation.There is a large variation in monthly precipitation,but relatively constant daily temperatures withan annual average in the range of 26–27 o C and avariation between months in the range of 4° to 5 o C.As shown in Table 3.11, precipitation is highest inthe months from May to November, accounting for90 percent of the annual rainfall. Typhoon eventscan pass over HCMC. The dry season runs fromDecember to April and can cause drought conditionsregularly. Extreme droughts have occurred in1993, 1998, and 2002.38This is calculated on the basis of the expenditure typicallyrequired to meet a minimum daily calorific requirementof 1,700 Kcals. A number of qualifications need to be made,as the official figure does not include migrants.Estimating Flood Impacts and Vulnerabilities in Coastal Cities | 39
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© 2010 The International Bank for
Page 7 and 8: Figure 4.6 Damage Costs Associated
Page 9: AcknowledgmentsThis synthesis repor
Page 13 and 14: Executive SummaryIntroduction and R
Page 15 and 16: For each city, complex hydrometeoro
Page 17 and 18: infrastructure but a high emission
Page 19: these include strategies that focus
Page 23 and 24: policy implications have broader re
Page 25: 2Methodologies forDownscaling, Hydr
Page 28 and 29: Table 2.1 ■ Climate Change Foreca
Page 30 and 31: Return periods considered 18In this
Page 32 and 33: Figure 2.2 ■ Manila Rainfall-Runo
Page 34 and 35: Figure 2.3 ■ Estimation of Damage
Page 36 and 37: sion and distribution lines, and en
Page 38 and 39: Figure 2.5 ■ Possible Relationshi
Page 40 and 41: prices and the same prices are appl
Page 43 and 44: 3Estimating Flood Impactsand Vulner
Page 45 and 46: Table 3.2 ■ Bangkok Monthly Avera
Page 47 and 48: Estimation of storm surge in the ca
Page 49 and 50: Climate Change Impact and Adaptatio
Page 51 and 52: Figure 3.5a ■ Affected Condensed
Page 53 and 54: Manila’s current climate—Tropic
Page 55 and 56: Table 3.6 ■ Manila Climate Change
Page 57: Figure 3.10 ■ Areas of High Popul
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
Page 93 and 94: of reducing vulnerability of the po
Page 95 and 96: 5Conclusions andPolicy Implications
Page 97 and 98: open land use is expected to be flo
Page 99 and 100: hydrometeorological data, yielding
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
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mercial and industrial establishmen
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ADB. The selection and prioritizati
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AnnexCAdaptation to IncreasedFloodi
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of people and institutions to manag
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THE WORLD BANK1818 H Street, NWWash
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Climate risks and adaptation in Asian coastal megacities: A synthesis

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