THE IMPACT OF CLIMATE CHANGE ON GROUNDWATER RESOURCES SYSTEM UNDER CONJUNCTIVE USE IN THE UPPER CENTRAL PLAIN

Abstract

The Upper Central Plain Basin of Thailand has high potential for social and economic development. It is also high-volume source of agricultural products, especially rice. However, in the drought year, water storage in the dams is inadequate to allocate for agriculture, and caused water deficit in many irrigation projects. Farmers need to find extra source of water by pumping the groundwater. This area is also affected from climate change phenomena, which cause significant decrease of the water storage in the dam and may cause further shortage in the future. The objective of this study is to characterize of groundwater system under conjunctive use, to analyze the impact of climate change, and to propose adaptation measures under climate change to alleviate drought in the future. Based on the analysis of groundwater systems in the present period, it was found that significant factors affecting groundwater storage are land recharge and groundwater pumping. The study developed the climate-soil based recharge formula that described the relationship between land recharge and rainfall, climate condition parameters and produced groundwater pumping potential map which classify the study area into 3 zones: low potential, intermediate potential and high potential for future pumping planning. The study of climate change impact concludes that the average demand, surface water supply and groundwater pumping will increase. The conjunctive use ratio in wet season, in near future will be the same as present, while it will decrease 14.29% in the far future. In dry season, the ratio will increase 23.08% and 45.83%, respectively. The conjunctive use ratio in annual, will increase 6.59% and 6.18%, respectively. The two proposed adaptation measures will reduce drought risk under climate change in the near future and far future.