www.iwmi.orgWater for a food-secure worldCurrent and Future Variability in the Hydrological Regime of the Koshi Basin, Nep...
Basin CharacteristicsArea considered in this study is the Koshi Basinupstream of Chatara in the mountainousregion of easte...
www.iwmi.orgWater for a food-secure worldProjected Climate Data for Climate Change Study:Downscaled using MarkSim Weather ...
www.iwmi.orgWater for a food-secure worldResults: Spatial Distribution of Precipitation, Actual ET and Water Yield•Average...
www.iwmi.orgWater for a food-secure worldResults: Simulated Seasonal Flow ContributionSimulated seasonal flow contribution...
www.iwmi.orgWater for a food-secure worldPercent change in precipitation during the a)winter, b)pre-monsoon,c)monsoon and ...
www.iwmi.orgWater for a food-secure worldPercent change in flow volume during the a)winter, b)pre-monsoon,c)monsoon and d)...
Change in Monsoon RainfallSRES Family – A1BWRF-ECHAM5 WRF-GFDL-V2 WRF-HADCM3PRECIS-HadCM3Q0 RegCM4-ECHAM5 WRF-CCSM3
Change in Monsoon Max. TemperatureWRF-ECHAM5 WRF-GFDL-V2 WRF-HADCM3PRECIS-HadCM3Q0 RegCM4-ECHAM5 WRF-CCSM3SRES Family – A1B
www.iwmi.orgWater for a food-secure worldResults: Minimum, maximum and mean precipitation in the Central mountain regionof...
www.iwmi.orgWater for a food-secure world
www.iwmi.orgWater for a food-secure worldSummary of Results for the Koshi Basin• (i) Higher maximum precipitation during m...
www.iwmi.orgWater for a food-secure world• Understanding of and adapting to existing climate variability as well as thecha...
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Current and Future Variability in the Hydrological Regime of the Koshi Basin, Nepal

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Presented by Luna Bharati at the Global Water Systems Project: Water in the Anthropocene Conference May 21-24th in Bonn, Germany.

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Current and Future Variability in the Hydrological Regime of the Koshi Basin, Nepal

  1. 1. www.iwmi.orgWater for a food-secure worldCurrent and Future Variability in the Hydrological Regime of the Koshi Basin, NepalL. Bharati , P. Gurung and L. Maharjan
  2. 2. Basin CharacteristicsArea considered in this study is the Koshi Basinupstream of Chatara in the mountainousregion of eastern Nepal and southern Tibet(57,760 km2)The average elevation of the basin is 3,800 mbut varies from 110 m at Chatara to more than8,000 m in the Great Himalayan RangeThe basin can be divided into the Trans-mountain Region, Central Mountain Region,Eastern Mountain Region, Central Hill Regionand Eastern Hill Region!(!(!(!(!(!(!(!(!(!(!(!(!(!(!(!(!(!(!(!(!(!(!(!(#*#*#*#*#*#*#*#*#*#*#*#*#*#*#*43004000222322222221141914061404132513241307130313011220121312121206111511081103106210221006285885695690684681670652650647630620606668.5627.5604.5Ü0 50 10025 kmLegend#* Flow Station!( Climate StationRiversKoshi Basin BoundaryCountry BoundaryINDIACHINANEPALINDIAINDIA Ü186243514932175171678 73111810751245342713576265585615385560722371306153543669674466423559 644074701947434137687679287729203148 524963392225503346262421LEGENDCountry boarderSubbasinTrans-mountain regionCentral mountain regionEastern mountain regionCentral hill regionEastern hill region0 40 80 12020 kmÜStudy Area: Koshi River Basin
  3. 3. www.iwmi.orgWater for a food-secure worldProjected Climate Data for Climate Change Study:Downscaled using MarkSim Weather Generator (RCM)(http://gismap.ciat.cgiar.org/MarkSimGCM/)- Average of CNRM-CM3, CSIRO-Mk3.5, ECHam5, and MIROC3.2- AR4-SRES: BL, A2 and B1- Period: 2000s (1971-2000) for BL2030s (2016-2045) for A2 and B12050s (2036-2065) for A2 and B1- Variable: Rainfall, Temperature (Max & Min), Solar RadiationMethods: Input Data
  4. 4. www.iwmi.orgWater for a food-secure worldResults: Spatial Distribution of Precipitation, Actual ET and Water Yield•Average annual precipitation ishighest in the Central Mountain(1775 mm) and Eastern MountainRegions (1418 mm)•The lowest rainfall during both thedry and wet season is the Trans-mountain region (meanprecipitation was 113 mm duringthe dry season and 307mm duringthe wet season186243514932175171678 73111810751245342713576265585615385560722371306153543669674466423559 6440747019474341376831767928487729222046 52496339255033262421LEGENDPrecipitation (mm)294 - 350351 - 500501 - 10001001 - 15001501 - 20002001 - 25002501 - 30003001 - 35003501 - 40004001 - 450050 10025 kmÜ(a)186243514932175171678 73111810751245342713576265585615385560722371306153543669674466423559 6440747019474341376831767928487729222046 52496339255033262421LEGENDActual ET (mm)189 - 250251 - 300301 - 350351 - 400401 - 450451 - 600601 - 650651 - 700701 - 750751 - 8170 50 10025 kmÜ(a)186243514932175171678 73111810751245342713576265585615385560722371306153543669674466423559 6440747019474341376831767928487729222046 52496339255033262421LEGENDNet Water Yield (mm)23 - 5051 - 100101 - 500501 - 10001001 - 15001501 - 20002001 - 25002501 - 30003001 - 35003501 - 40000 50 10025 kmÜ(a)• ET is mainly related to precipitation aswell as land cover•During both the dry and wet seasons,average Actual ET is highest in the Centraland Eastern mountain region and lowest inthe Trans-mountain region• Water yield is highest also inthe mountain region and lowestin the Trans-mountains• Range is quite big with lowest of5mm during the dry season inTrans mountain region to 1629mm in the Central mountain zone
  5. 5. www.iwmi.orgWater for a food-secure worldResults: Simulated Seasonal Flow ContributionSimulated seasonal flow contribution in annual flow under current and future climateUnder 2030sProjectionUnder 2050sProjection
  6. 6. www.iwmi.orgWater for a food-secure worldPercent change in precipitation during the a)winter, b)pre-monsoon,c)monsoon and d)post-monsoon seasons under the A2 climateprojections for the 2030’s
  7. 7. www.iwmi.orgWater for a food-secure worldPercent change in flow volume during the a)winter, b)pre-monsoon,c)monsoon and d)post-monsoon seasons under the A2 climateprojections for the 2030’s
  8. 8. Change in Monsoon RainfallSRES Family – A1BWRF-ECHAM5 WRF-GFDL-V2 WRF-HADCM3PRECIS-HadCM3Q0 RegCM4-ECHAM5 WRF-CCSM3
  9. 9. Change in Monsoon Max. TemperatureWRF-ECHAM5 WRF-GFDL-V2 WRF-HADCM3PRECIS-HadCM3Q0 RegCM4-ECHAM5 WRF-CCSM3SRES Family – A1B
  10. 10. www.iwmi.orgWater for a food-secure worldResults: Minimum, maximum and mean precipitation in the Central mountain regionof the Koshi Basin for observed, baseline, A2 and B1 projections for the 2030’s and2050’s
  11. 11. www.iwmi.orgWater for a food-secure world
  12. 12. www.iwmi.orgWater for a food-secure worldSummary of Results for the Koshi Basin• (i) Higher maximum precipitation during monsoon and post-monsoon and lower maximumprecipitation during winter (in A2 and B1 scenarios)• (ii) Increase in precipitation and flows in the Trans Mountain region during all the seasonsexcept for flows during the monsoon under the B1 scenario• (iii) Increase in post-monsoon precipitation and routed flow volumes in the whole basin(under A2 and B1 scenarios)• (iv) Decrease in winter precipitation and routed flow volumes in all the regions except theTrans Mountain• (v) Increase in the frequency of high flow peaks and decrease in the base flow portion ofrunoff.
  13. 13. www.iwmi.orgWater for a food-secure world• Understanding of and adapting to existing climate variability as well as thechanges in variability is critical for adaptation to future climates• There is still high level of uncertainty in future Climate Change projections• Instead of planning for certain trends, adaptation strategies need to plan forfuture uncertainty…– Will future climate lead to exposer that is outside the boundaries ofpast data ranges– increased frequency of extreme events such as both high-flows and low-flows– Investments in systems which reduce risk such as storage development,crop insurance schemes might be more effectiveConclusions

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