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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  • 2°C is the key target in global climate discussions, these COP conferences etcWe have 194 countries trying to get global agreement on this targetThe reason for 2Deg C is not to avoid CC impacts. We know that with 2deg we are going to have impacts .The reason is to avoid some of the catastrophic impacts – the global tipping points – destabilisation of the indian monsoon, collapse of the greenland or antarctic ice sheets etc… these will fundamentally transfrom the world in ways which will really threaten our ability as a species to surviveBut is 2Deg C realistic?
  • we know there is an approximately linear (Quasilinear) relationship between atmospheric CO2 and global temperature change
  • Two key features of the distribution: the mean around which the distribution is centered. The spread in the data – i.e. the range in variability of the parameter
  • Globally by 2050 mean annual temperatures will increase by 1.2-2.2 Deg CIn the LMB mean annual temperatures will increase by xxx Deg C
  • Maybe delete as this info is covered better in the next slide
  • Identify the major floodplains of the Mekong and show Cambodia/Delta floodplain to be the dominant one
  • Due to its size, the Mekong basin is compromised of highly variable terrain. Upland areas of the Annamites and northern Lao are extremely rugged with poor access. This means that hydroclimate conditions vary markedly over short distances while coverage of monitoring stations remains sparse (see Section In these areas localised high points, such as karst formations which rise rapidly, can occur in flatter valley terrain and cannot be accurately picked up by the Digital Elevation Model (DEM) used to define topography. The DEM will resolve the topography into an average elevation within the cell which will be higher than the valley level but lower than the local peak, which means that elevations for valley areas could be overestimated while the high point will be ignored. This issue is symptomatic for all hydrological modelling work in the Mekong Basin and can only be resolved through the development of higher resolution topographical data.Groundwater remains the most poorly monitored water resource in the Mekong basin, yet plays an important role in monthly, seasonal and inter-annual water storage. In some areas such as central Lao PDR, there is evidence suggesting that groundwater discharges back into streams during the dry season (table 3-1). Application to tropical climates: typically statistical downscaling uses multiple regression techniques which assume climate data is normally distributed. While this is generally the case for temperature data it may not the case for precipitation in monsoon.System feedback: changes in the hydroclimate will influence changes in other ecosystem components such as vegetation which could feedback to the hydroclimate by altering micro-climates, onset dates of seasonal rains, convection dynamics in the regional atmosphere or the persistence of dry spells. Statistical models fitted to observational data do not have the capacity to pick up on these important feedbacks.
  • 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
    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
    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
    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
    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
    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
    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
    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