ASSESSMENT OF WATER DEMAND AND SUPPLY UNDER FUTURE CLIMATIC CHANGE CONDITIONS

1. ASSESSMENT OF WATER DEMAND AND SUPPLY UNDER FUTURE CLIMATIC CHANGE CONDITIONS IN THE MAE KLONG RIVER BASIN, THAILAND Presented by Chollada Rojrungtavee Thesis Advisor: Dr. Mukand S. Babel FoS: Water Engineering and Management

2. INTRODUCTION • Climate change impacts on water resources • Hydrological uncertainties • Uncertainties in water availability and demand • Hydroelectric power production • Water quality • Habitats to living organisms • Objectives: • To estimate the current and future water demand of the main water consumption sector in Mae KIong River Basin under climate change conditions • To evaluate water balance situation and power production under climate change condition using reservoir operation

3. INTRODUCTION: Scopes of Study • Study Area • Mae Klong River Basin • Reservoirs • Srinagarind reservoir • Vajiralongkorn reservoir • Main Water Consumption Sector • Irrigation sector (GMKIP) • Inter-basin transfer sector • Salinity control sector • Years of Consideration • Base year 2005 • Future years 2025, 2050 and 2095

4. Greater Mae Klong Irrigation Project • Total area • 4,833.44 km2 • Provinces • Suphanburi • Nakornpathom • Karnchanaburi • Samutsakorn • Petchburi

5. Water Consumptions • Main water requirements • Irrigation • Inter-transfer to Ta-Chin River Basin • Domestic and industrial together is less than 2% • Salinity control requirement at estuary • 1,571 MCM/year

6. Study Area Identification Future Irrigation Water Requirements in the Greater Mae Klong Irrigation Project for 2025, 2050 and 2095 Future inflows into Vajiralongkorn and Srinagarind reservoirs for 2025, 2050 and 2095 Reservoir Operation Model (HEC-ResSim) Future water balance situation in Mae Klong River Basin METHODOLOGY

7. Irrigation Water Requirement • The estimation of irrigation water requirements is separated into two methods for upland crops and lowland paddy Irrigation Requirement Estimation Calculation of Reference Crop Evapotranspiration (ETo) Calculation of Effective Rainfall Penman-Monteith Method Upland Crops USDA Soil Conservative Service Method For Ptot < 250 mm: Peff = Ptot (125 – 0.2 Ptot)/125 For Ptot > 250 mm: Peff = 125 + 0.1 Ptot Lowland Paddy Rice Soil-Water Balance Method Inputs: Maximum and minimum temperature, relative humidity, sunshine hours and windspeed

8. Irrigation Water Requirement Upland Crops Calculation of Reference Crop Evapotranspiration (ETo) Calculation of Effective Rainfall Penman-Monteith Method USDA Soil Conservative Service Method Calculation of Actual Crop Evapotranspiration (ETc) ETcrop = Kc . ETo Calculation of Irrigation Requirement IRReq = ETcrop - Peff

9. Irrigation Water Requirement Lowland Paddy Irrigation Requirement IR = U + LP + WL + P – ER + S2 – S1 Where IR = irrigation requirement U = crop water requirement LP = land preparation WL = normal water level P = percolation ER = effective rainfall S1, S2 = storages

10. Irrigation Water RequirementData Requirement Rainfall

11. Irrigation Water RequirementData Requirement Wet Season Crops • Paddy = 1170.3 km2 • Sugarcane = 600.5 km2 • Sweet corn = 67.7 km2 • Maize = 179.4 km2 • Green bean = 11.7 km2 • Mango = 618.6 km2 Cropping area • Dry Season Crops • Paddy = 1208.7 km2 • Sugarcane = 100.3 km2 • Sweet corn = 263.3 km2 • Maize = 9.1 km2 • Green bean = 239.5 km2 • Asparagus = 151.9 km2

12. Irrigation Water RequirementData Requirement Cropping Pattern

13. Vajiralongkorn dam Srinagarind dam GMKIP Inter-basin transfer to Ta-Chin River Basin Salinity control Gulf of Thailand Figure 3.5 Configuration diagram for simulation of Mae Klong river basin – minor demand tributaries not included Reservoir Operation Simulation • Required inputs for the simulation: • Inflows into reservoirs • Reservoir characteristics • Operation rule curves • Basin water demand

14. Reservoir Operation SimulationData Requirement Inflows into the reservoirs

15. Reservoir Operation SimulationData Requirement Reservoir Characteristics Srinagarind Reservoir Vajiralongkorn Reservoir

16. Reservoir Operation SimulationData Requirement Existing Rule Curves and Water Level – Srinagarind Reservoir

17. Reservoir Operation SimulationData Requirement Existing Rule Curves and Water Level – Vajiralongkorn Reservoir

18. RESULTS AND DISCUSSIONIrrigation Requirements Upland Crops Lowland Paddy

19. RESULTS AND DISCUSSIONIrrigation Requirements Total Irrigation Requirement

20. RESULTS AND DISCUSSIONWater Balance Situation Year 2005 Year 2025 Year 2050 Year 2095

21. RESULTS AND DISCUSSIONWater Balance Situation • Year 2005 • Inflow and release

22. RESULTS AND DISCUSSIONWater Balance Situation • Year 2005 • Water supply and requirement at each control point

23. RESULTS AND DISCUSSIONHydroelectric Power Production Vajiralongkorn Reservoir

24. CONCLUSIONS AND RECOMMENDATIONS • CONCLUSIONS • Rainfall tends to increase in large amount in wet season, but dry season rainfall remains more or less similar to the present amount. • With climate change condition, the total irrigation requirements in Greater Mae Klong Irrigation Project decrease significantly during the wet season and some increment during the dry season • Large amount of water is available within the basin, but still small shortages occur for the dry season irrigation requirement and at the salinity control point • RECOMMENDATIONS • Proper water management measures should be proposed to allocate enough amount of water to each water demand points to avoid shortages • Further studies on estimating the impacts of climate change on inter-basin transfer and salinity control demands could be done and included in the reservoir operation • Land use and irrigation area changes could be considered for the future development in the basin • Operation rule curves could be considered for the changes over the next 100 years

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