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  • Coastal Cities and Adaptation to Climate Change: Bangkok StudyChanchai VitoolpanyakijDirectorDepartment of Drainage and SewerageBangkok Metropolitan Administration

  • Climate forcing on BangkokTemperature changesRainfall changes (local & upper catchment)Sea level riseAltered frequency of extreme events (storm surge)Compounding factorsFlat topographyLand subsidence

  • Local and global temperatureThere is a robust linear relationship between local temperature increase and global mean temperature increasevertical axis Bangkok mean temperature changehorizontal axis - global mean temperature changeSERS (Special Report on Emissions Scenarios) Red - A1B, blue - B1solid black line - least-square fit to all data pointsSource: Study on Climate Impact Adaptation and Mitigation in Asian coastal mega cities: Interim Report, JBIC, 2008

  • Local temperature trendsAnnual mean (1961-2007) minimum and maximum temperatures in Bangkok is risingOverall, Thailands temperature rise show similar trend during the same period

  • Sea level riseSea level rise (Increased coastal erosion, inundation of coastal wetlands, Increased risk of flooding and storm damage)Upper Gulf of Thailand (includes Bangkok) - most vulnerable to sea-level rise in ThailandSource: Tidal record analysis by the consultant. Yearly averaged values are shown here

  • Extreme eventsStorm surges and typhoons are not uncommonMost recent - typhoon LINDA (1997)caused strong winds and heavy rainfallsignificant wave height of 3-4 m was measuredAltered frequency of extreme weather events (Increased waves and surges, Altered cyclone zones)Storm surge

  • A gloomy future!IPCC SERS (Special Report on Emissions Scenarios) Case

    Source: Study on Climate Impact Adaptation and Mitigation in Asian coastal mega cities: Interim Report, JBIC, 2008Strom surge: 61 cm

  • Altered flood risks..Floods due to altered extreme precipitation from the upstream, and in the Bangkok area and tide are crucial for Bangkok

  • Future floodsMax depth (30-yr return period)2008 conditionMax depth (30-yr return period)2050 A1FI + Sea level rise + Land subsidence + Storm surge condition

  • Structural measures (1995 to present)Dike along both sides of the Chao Phraya RiverKings Dike to protect BMA east side Dike to protect BMA west sideDike to protect BMA east side expansion (under construction)Dike to protect Suwanaphum International AirportImprove Pumping System+2.50 to +3.00 m.MSL+3.60 m.MSLBangkokExisting and planned flood protection systems will not have enough capacity to cope with the climate change of A1FI scenario at the return period higher than 10 years

  • Structural measures earlier proposalLarge storage dam in the upper basinBarrage at the river mouthDiversion channelCoastal erosion protection the shoreline on the west of the Chao Phraya River has been eroded about 5 to 10 m per year

  • Structural measures current proposalDikes, pumps, and drainage canal improvementDike crest elevations in the future include land subsidence of 0.20 m and free board of 0.30 mThree new pumping stations at Klong Khun Rat Phinit Chai, Phasi Charoen and Sanam Chai (capacities of 100, 400 and 200 m3/sec for flood at 30-year return period)Improvement of drainage canals

  • Maximum future inundationInundated area - reduced from 744.34 to 362.14 km2 or decreased 382 km2 or 51 .35%.Without proposed structural adaptationWith proposed structural adaptation

  • Coastal erosion protection current proposalPursue shoreline protection of the western area of the Chao Phraya River (along the shoreline of Bang Khun Thien) as proposed by BMA (2007)Shoreline of the eastern area of the Chao Phraya River, raise the crest of the proposed rock-pile embankments along all the length of the embankments.The total estimated costs are 35,228 million baht to protect the against a 30-yr return period flood of the futureNon structural measures (next presentation)

  • Thank you

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