Climate risks and adaptation in Asian coastal megacities: A synthesis

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sion and distribution lines, and energy distributioncenters depends on whether these facilities are inthe flood-affected area of each city. If they are, thenthe extent of damage is estimated and replacementand repair costs are used to value these damagesbased on cost information available with governmentdepartments. In most cases, electric utilitieshave strict rules for cutting electricity during certaintypes of floods. This leads to revenue losses, whichwere estimated in the Bangkok case study. In termsof direct costs, future power generation plants forBangkok and Samut Prakarn are planned outsidethe cities and there will be no direct impact. TheManila study did not estimate energy-related costs.As with the case of the energy sector, costs towater and sanitation systems are evaluated only ifit is established that there is a likelihood of flooddamage to specific subcomponents such as waterintake facilities, pumping stations, water treatmentplants, main lines to storage tanks, storage tanks,distribution networks, and so on. In the case ofBangkok, it is assumed that water supply will becomedysfunctional if water floods reach 2 metersabove the ground surface. This will disrupt waterservices to the area and result in revenue losses tothe utilities as well as other costs, including healthcosts. The calculation of sales loss for the water supplysystem due to flood damages in Bangkok wasestimated as follows:Water supply sales loss = No. affected usersx water demand per user x water sales ratex flood durationThe data for this estimation came from the five-yearrecord of the Metropolitan Waterworks Authority,which indicates water sales for a residential unit are0.48 m 3 per day per household and water revenue is2.06 baht per m 3 . Water sales for a nonresidential unitare 3.71 m 3 per day per customer and water revenueis 2.83 baht per m 3 . In the Bangkok study, direct damageto the water supply and sanitary infrastructureis not assessed since they are protected from theworst possible flood in the future. The calculationof income losses to sanitation service providersbecause of the shutdown of sanitation services wassimilarly undertaken. The Manila study did not findmajor costs associated with the water delivery sectorbecause of the position of the pipes and extentof pressure in them.Estimating income lossesAs previously noted, each city estimates the populationlikely to be affected by 2050 floods. Wherepossible, survey data and other secondary sourceswere used to identify the characteristics of the affectedpopulation, particularly to examine whetherfloods will affect the poorest communities.Income losses to the commercial sectorIn order to estimate income losses from floods, theManila and Bangkok case studies examined lossesto firms and individuals. During the duration of theflood, income losses are borne by the private commercialsector because of a halt in their activities.Since it is difficult to directly estimate these costswithout detailed production information, whereavailable, national statistics on income per day associatedwith different kinds of commercial structureswere used.The Bangkok study identified the number ofbuildings in flood-affected areas and then, basedon the duration of the flood, estimated the rate ofdamage to these buildings. To obtain business losses,the Bangkok case study then identified the averageincome per day from commercial establishmentsbased on business surveys. The loss in value addedper day (net income) was adjusted due to savings inbusiness expenditure when an operation is closeddown. The net commercial income was estimatedto be THB 4930 ($149) per establishment per day.A similar accounting was used to estimate averageincome to industrial establishments. These averagevalues are multiplied by the number of days of floodingand the number of buildings affected by floods toestimate income losses from commerce and industry.The Manila case study took a similar approach.The analysis was based on a 2008 survey on businessincome losses to flood-affected firms. The studyused data on sales losses as a substitute for incomeor profit data, which were unavailable. Buildingsthat were affected by floods were categorized accordingto different commercial activities; each floorwas assumed to host one firm. By multiplying the16 | Climate Risks and Adaptation in Asian Coastal Megacities: A Synthesis Report
sales loss data (categorized by type of economicactivity) by the number of affected buildings in eacheconomic category, the study established the valueof income losses to the commercial sector.Estimation of income losses for poor andnon-poor householdsHouseholds who work in flood-affected areas maylose income during the duration of the flood. Ageneral assumption made in the Bangkok case isthat salaried workers will not see income lossesfrom floods. However, the informal sector needsfurther accounting. In Bangkok, the low-incomehousing developments, called condensed housing,in flooded areas are identified and—based onestimates of household size—the number of dailywage earners in this area is estimated. Then basedon the daily wage rate, the income loss to poor andnon-poor households is calculated.The Manila case study examines income lossesto workers in the formal and informal sectors. Becauseof lack of data on number of households, thecase study, like Bangkok, relied on the number ofbuildings affected by floods. Non-poor residentswere assumed to occupy residential buildings at therate of 1.5 households per building. This allowed theManila study to estimate the total number of nonpoorresident households in flood-affected “formal”residential buildings. The total number of affectedhouseholds was multiplied by the average incomeper household (based on government statistics) toobtain income losses to the formal sector.To establish losses to the poor, the Manila studyfirst estimated the number of informal structuresaffected by floods. It was assumed that at least twohouseholds live in each structure. Thus, the totalnumber of affected households was estimated.Again, using government statistics on the povertylevel per day of PHP 266 per household, the totallosses to the informal sector was then established.Limited analysis of health impacts in thecity studiesAn important question concerns the impact of floodson public health. Each city is different and has healthimpact data based on previous experience with floodsand expert advice. The main diseases associated withfloods are diarrhea, conjunctivitis, athlete’s foot,malaria, cholera, and typhoid. Ideally, we wouldrequire information on different outbreaks and costper episode per person for specific diseases in orderto value health impacts. However, this is difficultto obtain and some approximations are made. TheBangkok study makes an attempt to examine healthcosts associated with floods. In this case study, thenumber of individuals affected by floods is estimatedand multiplied by the average per person health costsassociated with hospital admissions. This is clearly afirst approximation for what might be the real costson health from flooding. However, lack of data, anddifficulties in establishing dose-response informationrelated to different flood-related diseases, leadto this more simplistic analyses. The Manila studydoes not estimate the health costs from floods eventhough it makes an attempt to estimate some of thehealth impacts of flooding. A more detailed analysisof health impacts needs to be carried out as a followupto this study.Assessment of Damage Costsin the HCMC StudyThe HCMC study used a macro-approach to assessdamage costs. Two different methods were used tocalculate the cost of climate change at an aggregatemacro-level: (1) cost estimates using land values; and(2) cost estimates based on aggregate GDP loss. Themethodology applied in each of these approachesand the results obtained are described below.The land value approachEconomically speaking, the value of any asset isthe sum of the value it is expected to generate overtime, discounted to reflect people’s preferences forconsumption in the present. The same is true forland. In principle, the current value of the land stockin HCMC is the value of future production that canbe expected to be generated with this asset. Landvalue can be a particularly good guide to the cost ofclimate change as land values capitalize most valuesthat need to be captured in any assessment of cost(such as roads, railways, water supply systems,Methodologies for Downscaling, Hydrological Mapping, and Assessing Damage Costs | 17
Page 4 and 5: © 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 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 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
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
Page 108 and 109:
mercial and industrial establishmen
Page 110 and 111:
ADB. The selection and prioritizati
Page 113 and 114:
AnnexCAdaptation to IncreasedFloodi
Page 115:
of people and institutions to manag
Page 120:
THE WORLD BANK1818 H Street, NWWash
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Climate risks and adaptation in Asian coastal megacities: A synthesis

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