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

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

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

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

Water Consumptions DomesticIndustrialIrrigation Inter-basin transfer to Ta-Chin Total Water Requirement (MCM/year) , , , Percentage of Water Requirement 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

METHODOLOGY 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

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

Irrigation Water Requirement Upland Crops Calculation of Reference Crop Evapotranspiration (ET o ) Calculation of Actual Crop Evapotranspiration (ETc) Calculation of Effective Rainfall Calculation of Irrigation Requirement Penman-Monteith Method ET crop = K c. ET o USDA Soil Conservative Service Method IR Req = ET crop - P eff

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

Irrigation Water Requirement Data Requirement Rainfall

Irrigation Water Requirement Data Requirement Wet Season Crops Paddy = km 2 Sugarcane = km 2 Sweet corn = 67.7 km 2 Maize = km 2 Green bean = 11.7 km 2 Mango = km 2 Dry Season Crops Paddy = km 2 Sugarcane = km 2 Sweet corn = km 2 Maize = 9.1 km 2 Green bean = km 2 Asparagus = km 2 Cropping area

Irrigation Water Requirement Data Requirement Cropping Pattern

Reservoir Operation Simulation Vajiralongkorn damSrinagarind 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 Required inputs for the simulation: Inflows into reservoirs Reservoir characteristics Operation rule curves Basin water demand

Reservoir Operation Simulation Data Requirement Inflows into the reservoirs

Reservoir Operation Simulation Data Requirement Highest water level180m MSL Lowest water level159m MSL Tail water55.5m MSL Highest storage17,745MCM Lowest Storage10,265MCM Surface area418.8km 2 Annual evaporation351.1MCM Power Plant Installed capacity360MW Spillway TypeChute Crest elevation171m MSL Control gates3 radial gates Capacity2,420m 3 /s Highest water level155m MSL Lowest water level135m MSL Tail water87m MSL Highest storage8,860MCM Lowest Storage3,012MCM Surface area388km 2 Annual evaporation210MCM Power Plant Installed capacity300MW Spillway TypeChute Crest elevation146m MSL Control gates2 radial gates Capacity3,200m 3 /s Reservoir Characteristics Srinagarind ReservoirVajiralongkorn Reservoir

Reservoir Operation Simulation Data Requirement Existing Rule Curves and Water Level – Srinagarind Reservoir

Reservoir Operation Simulation Data Requirement Existing Rule Curves and Water Level – Vajiralongkorn Reservoir

RESULTS AND DISCUSSION Irrigation Requirements Upland Crops Lowland Paddy

RESULTS AND DISCUSSION Irrigation Requirements WetDryWetDryWetDryWetDry Volume (MCM) Total Relative change (%) Total Irrigation Requirement

RESULTS AND DISCUSSION Water Balance Situation Control PointsAvailable at CPShortage at CP WetDryWetDry VJK SNR GMKIP DIV to Ta-Chin Salinity Control Total Control PointsAvailable at CPShortage at CP WetDryWetDry VJK SNR GMKIP DIV to Ta-Chin Salinity Control Total Control PointsAvailable at CPShortage at CP WetDryWetDry VJK SNR GMKIP DIV to Ta-Chin Salinity Control Total Control PointsAvailable at CPShortage at CP WetDryWetDry VJK SNR GMKIP DIV to Ta-Chin Salinity Control Total Year 2005Year 2025 Year 2050Year 2095

RESULTS AND DISCUSSION Water Balance Situation Year 2005 Inflow and release

RESULTS AND DISCUSSION Water Balance Situation Year 2005 Water supply and requirement at each control point

RESULTS AND DISCUSSION Water Balance Situation Year 2025 Inflow and release

RESULTS AND DISCUSSION Water Balance Situation Year 2025 Water supply and requirement at each control point

RESULTS AND DISCUSSION Water Balance Situation Year 2050 Inflow and release

RESULTS AND DISCUSSION Water Balance Situation Year 2050 Water supply and requirement at each control point

RESULTS AND DISCUSSION Water Balance Situation Year 2095 Inflow and release

RESULTS AND DISCUSSION Water Balance Situation Year 2095 Water supply and requirement at each control point

RESULTS AND DISCUSSION Hydroelectric Power Production Vajiralongkorn Reservoir

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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