A thesis final report submitted in partial fulfillment of requirements for the Degree of Master of Engineering

Thesis (M.Eng.) - Asian Institute of Technology, 2008

Climate change and its effects have become more concerning to many countries all over the globe, contributing to uncertainties in water availability and demand. The studies of changes on water balance situation due to the change in climate are necessary to estimate its impact. The study was confined to Mae Klong River Basin, Thailand to assess the water balance situation by comparing water required and water supplied in the present and future under climate change conditions using reservoir operation model. The irrigation water requirements were estimated using two models of CROPWAT, recommended by FAO and the soil-water balance for upland crops and lowland paddy, respectively. Future climatic data used were precipitation, temperature, relative humidity, sunshine hours and wind speed, all predicted from climate model of ECHAM4 under A2 scenario. The results show some significant reduction in crop water requirement in the future periods, especially in the wet season. The estimated total irrigation requirements were 2,235.08 MCM/year for the base year 2005 and reduced to 1,975.78 MCM/year, 2024.66 MCM/year and 1,897.80 MCM/year for 2025, 2050 and 2095, respectively. Reservoir operations were simulated for Srinagarind and Vajiralongkorn dams on a daily basis to study the effects of changes in irrigation water demands on the water balance situation in the river basin. The results show some small shortages during both wet and dry season for the irrigation and salinity control requirements for some particular months with low flows. In year 2005, 155.49 MCM in wet season and 298.33 MCM in dry season were not satisfied. For the future year periods, the total shortages are 105.60 MCM, 97.25 MCM and 12.01 MCM in wet season for 2025, 2050 and 2095, respectively and 164.43 MCM, 140.06 MCM and 150.05 MCM in dry season for 2025, 2050 and 2095, respectively.