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Mekong ARCC Climate Change and Hydrology Modeling Methods and Results

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At the Interim Results Workshop, the Modeling Team presented the climate change and hydrological modeling results for the LMB. The modeling team consists of Mr. Tarek Ketelsen, Mr. Jorma Koponen, Mr. Jeremy Carew-Reid, Mr. Simon Tilleard, Mr. Mai Ky Vinh, and Mr. To Quang Toan.

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Mekong ARCC Climate Change and Hydrology Modeling Methods and Results

  1. 1. Climate andhydrological change:methods and results Tarek Ketelsen Jorma Koponen Jeremy Carew-Reid Simon Tilleard Mai Ky Vinh To Quang ToanICEM – International Centre for Climate Change Impacts and Adaptation Study Environmental Management Interim Results workshop 31 October – 1 November 2012
  2. 2. Contents1. Climate change and the Mekong Basin2. Overview of the methodology3. Basin-wide findings4. Challenges & limitations 2
  3. 3. CLIMATE CHANGE & THEMEKONG BASIN 3
  4. 4. Hydroclimate features of the Mekong Basin40,00035,000 KRATIE30,000 PAKSE25,00020,000 TAN CHAU15,000 VIENTIANE10,000 CHIANG SAEN 5,000 CHAU DOC 0 1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 4
  5. 5. Climate changes Hydrological changes Agricultural Ecological zones zones Species “zones” Commercial Subsistence Aqua- Traditional Live- Crop wild NTFPs Wild fish Wildlife crops crops culture crops stock relatives catch Climate Adaptation options changes Hydrological changes Agricultural Ecological zones zones Species “zones”Commercial Subsistence Aqua- Traditional Live- Crop wild NTFPs Wild fish Wildlife crops crops culture crops stock relatives catch Adaptation options
  6. 6. ARCC time-slices • ARCC Vulnerability Projections centered on 2050 (2045-2069) – 2050 allows for identification of the CC trends to be established with confidence – show us what direction we are moving, helping to set adaptation response • ARCC will also consider 2030 and Global 2 C 6
  7. 7. 2 C – a compromise with nature to avoid catastrophic climate change> 2 C → + 2 to 7m SLR>300yrs> 3-5 C → +5 m SLR > 2 C → ????>300yrs 7 Source: Adapted from (Schellnhuber, 2012and Lenton et al 2008)
  8. 8. Global CC projectionsB1• Population peaking at 9bil. and declining after 2050• Reductions in material intensity• Aggressive transition to clean & resource efficient technologies• Emphasis on globally connected economies• Over last decade rates of C0₂ emissions have exceeded even the most extreme scenarios – 2008 emissions +37% above 1990 levels – 2010 emissions +5% above 2008 8 – Increased mean global temperatures by 0.8 C Source: IPCC, 2007
  9. 9. Emission thresholds• Budget of 750Gt C0₂ remaining before we reach 2°C• Global emissions for all GHGs need to peak by 2015-2020• 5-9% annual emissions reduction rate • 25-40% emissions reduction of developed countries by 2020 • 50% global emissions reduction by 2050 Source: WBGU Special Report 2009• Unlikely that climate change can be limited to 2 C• Vulnerability assessments need to project beyond 2 C to understand the trends 9• By 2050, the Mekong Basin is beyond 2 C
  10. 10. METHODOLOGY 10
  11. 11. Assessment steps MEKONG HYDROCLIMATE MEKONG SYSTEMS BASELINES BASELINEHydrological Floodplain Crop Yield Crop suitability modelling modelling modelling modelling CHARACTERISATION OF EXPOSURE CHARACTERISATION OF SENSITIVITY 11 MEKONG SYSTEM CAM ASSESSMENT
  12. 12. Projections of future emissions and global GHG concentrations IPCC EMISSION SCENARIOS A1 B1 A2 B2Hydroclimate Projections of future atmospheric climate, atmospheric & ocean dynamicsassessment process BCCR- GCMs – GLOBAL CIRCULATION MODELS CCSM3 CGCM3.1 CGCM3.1 CNRM- CSIRO - ECHMA5/ ECHO-G BCM2.0 (T47) (T63) CM3 MK3.0 MPI-OM FGOALS- GFDL- GFDL- GISS- GISS-EH GISS-ER INM- IPSL-CM4 G1.0 CM2.0 CM2.1 AOM CM3.0 MICROC3. MICROC3.2 MRI- PCM UKMO- UKMO- 2 (hires) (medres) CGCM2.3. HADCM3 HADGEM 2 1 Downscaled projections of future climate at the basin-level CLIMATE DOWNSCALING DYNAMICAL STATISTICAL PATTERN (PRECIS) PRECIS Vietnam 2009 Mekong Basin 2009 Southeast (WeADAPT) (Cai et al, 2008) Asia 2003 (SEASTART) Prediction of future hydrological regime HYDROLOGICAL MODELLING VMOD VMOD MRC DSS VMOD SLURP CSIRO Songkhram Mekong Delta Mekong Mekong Mekong Mekong 2004 2008 Basin 2010 Basin 2011 Basin 2011* Basin 2009 (Aalto Uni & (Aalto Uni & (MRC & (Aalto Uni & (QUEST) 12 (18 sub- SEASTART) SEASTART) IWMI) ICEM) (no Mekong basins) floodplain)
  13. 13. Key steps 1. Projections of future emissions• Quantification of future climate change threats• Links changes in global 2. Projections of future atmospheric systems to regional and and ocean dynamics local areas of interest• Based on best available 3. Downscaling projections to the Mekong Basin science 4. Predicting future changes in the basin hydrological regime 5. Predicting future changes in the Delta floodplain environment & project site 13
  14. 14. 1. IPCC Emissions ScenarioA1B• world of rapid economic growth• introduction of more efficient technologies 14• global population peaking by 2050 (9bil.)• a balance between fossil intensive and non-fossil energy sources Source: CSIRO, 2009
  15. 15. 1. IPCC Scenarios – new developmentsIPCC AR5 (2014)• SRES scenarios will be replaced with a set of Resource Concentration Pathways (RCPs) – a set of scenarios relating to radiative forcing and GHG concentrations in the atmosphere – not directly linked to any socio-economic futures• Can be linked to IPCC scenarios 15 Source: Moss et al, 2012
  16. 16. 2. Global Circulation Models• Two earlier studies (Cao et al, 2009; Eastham et al, 2008) reviewed the performance of 17/24 IPCC AR4 GCMs for suitability to the Mekong region• In general, models perform better for temperature than precipitation• 6 were chosen based on their ability to replicate daily historical temperature and rainfall data Climate model CO2 Scenario Abbreviation Data period Model resolution (degrees) CCCMA_CGCM3.1 A1b, B1 ccA, ccB 1850-2300 3.75° x 3.75° CNRM_CM3 A1b, B1 cnA, cnB 1860-2299 2.8° x 2.8° GISS_AOM A1b, B1 giA, giB 1850-2100 3° x 4° MIROC3.2Hires A1b, B1 miA, miB 1900-2100 1.1° x 1.1° MPI_ECHAM5 A1b, B1 mpA, mpB 1860-2200 1.9° x 1.9° NCAR_CCSM3 A1b, B1 ncA, ncB 1870-2099 1.4° x 1.4° 16
  17. 17. 3. Statistical Climate DownscalingPurpose: reduce the geographical scope so that resolution can be improved  Assumes local climate is conditioned by large-scale (global) climate  does not try to understand physical causality  GCM output is compared to observed information for a reference period to calculate period factors  Period factors are then used to adjust GCM time-series  Downscaling undertaken for 166 temperature & precipitation stations 17
  18. 18. 4. Basin wide hydrological modelling• VMod model• 15 years of custom development for the Mekong• area-based distribution of hydro-meteorological impacts of climate change• Computes water balance for grid cells (5x5km)• Baseline:1981 – 2005• Future CC: 2045 - 2069• Can predict changes in: – Rainfall – Runoff – Flows – Infiltration – evapotranspiration 18
  19. 19. 5. Flood modelling• MIKE-11• Uses Vmod to establish boundary conditions• Divides the floodplain into zones (>120 in the delta)• Calculates small area water balances – 25,900 water level points – 18,500 flow points• Quantifies the changes in depth and duration of flooding due to changes in upstream hydrology and sea level riseFlooding Assessment scenarios• Average Flood + 0.3m SLR• 1 in 100yr Flood + 0.3m SLR 19• 1 in 100yr Flood + 0.3m SLR + Cyclone event
  20. 20. MAIN FINDINGS 20
  21. 21. CC assessment parameters• Max/min daily Temperature• Seasonal rainfall• Timing of the monsoon• Peak rainfall events• Erosion potential• Drought• Storms & cyclones• Soil water availability• River flow• Hydro-biological seasons• Flooding (depth & duration) 21
  22. 22. Interpreting Climate Change: Shifts & variability1. Shift in the Mean2. Historic variability 13. future variability  3–2= variability4. Climate experienced in baseline but no longer experienced with CC5. Climate common in baseline but less frequent with CC 36. Climate becoming more frequent with CC 27. New climate never before experienced 4 5 6 7 22
  23. 23. CHANGES IN TEMPERATURE 23
  24. 24. Max temperature Annual + 5-7% + 10-15% 24
  25. 25. Max temperature Dry Season + 10-13% 25
  26. 26. Max Temperature Wet + 14-19% 26
  27. 27. Min. temperature Annual + 10-30% 27
  28. 28. CHANGES IN RAINFALL 28
  29. 29. Mean Annual precipitation change + 10-18%• Text 29
  30. 30. Mean Wet Season precipitation change• Text + 11-14% 30
  31. 31. Mean Dry Season precipitation change + 15-23%• Text - 3-10% 31
  32. 32. Change in Monsoon timing 1 • Monthly rainfall >200mm 3 2 41. Chiang Rai 62. Sakon Nakhon3. Khammoun 7 54. Champassak5. Mondolkiri6. Gia Lai7. Kampong Thom8. Kien Giang 8 32
  33. 33. CHANGES INSTORMS, DROUGHTS &EXTREME EVENTS 33
  34. 34. Change in peak precipitation + 16-21% 34
  35. 35. Change in peak runoff &erosion potential + 40 ++% 35 +
  36. 36. Agricultural Drought Rainfall < 0.5* PETIncrease in areas experience >6months drought - 3 -25% +10-100% 36
  37. 37. Change in Storm Events Baseline summary (1956-2009) Date Intensity Frequency Landfall June Japan, Korea, China + + Eastern Seaboard July China, Northern Vietnam ++ + & Lao PDR 25% Aug – +++ +++ Northern & central Vietnam & Lao PDR – Sep occasionally Thailand 15% Oct – ++ ++ Central Vietnam, Southern Lao & Nov Cambodia Dec Southern Vietnam + + 41% With CC: 19% • Frequency will not change • Become more intense • Unclear whether trajectories will change 37
  38. 38. CHANGES IN DRY SEASONSOIL & SURFACE WATER 38
  39. 39. Subsurface Soil WaterAvailability Dry Season + 10-60% - 10-35% 39
  40. 40. Surface Soil WaterAvailability Dry Season + 5-30% - 15-30% 40
  41. 41. Change in Dry SeasonSurface Water Availability + 18 -25% - 4- 6.5% 41
  42. 42. CHANGES IN HYDROLOGY,FLOWS & FLOODING 42
  43. 43. % change in seasonal discharge + 20-40% Peak water level increase (m) + 20-40% 43DRY SEASON WET SEASON WET SEASON
  44. 44. Change in Mekong River Hydrology1 2 3 4 5 44
  45. 45. Hydro-biologicalSeasonal Shifts Source: MRC, 2009 45
  46. 46. Hydro-biologicalSeasonal ShiftsONSET• Wet season: 1-2 weeks earlier• Dry season: 1-3 weeks later• Transition Season: <1 week earlierDURATION• Wet season: 2-4weeks longer• Dry season: 1-2 weeks shorter• Transition Season: 1-2 weeks shorter 46
  47. 47. YR 2000 FloodDepths & extent
  48. 48. 2050 Flood Depth & extent• 1 in 100yr + 0.3m SLR 48
  49. 49. Duration of flood greater than 0.5 m depth
  50. 50. Duration of floodgreater than 1m depth 50
  51. 51. CHALLENGES & LIMITATIONS 51
  52. 52. Key challenges for climate change modelling1. Topographical complexity of the basin2. Variability in Mekong hydroclimate & selection of appropriate baseline3. Non-stationarity in hydroclimate conditions4. Understanding of Ground water interactions5. Application of statistical downscaling in tropical climates (validity of the normal distribution assumption)6. Accounting for system feedback – projecting changes in the stability of the Monsoon – Incorporating ENSO phenomena 52 Source: MRC, 2011
  53. 53. • Thank you! 53

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