Flow Budget Change of Groundwater System under Climate Change in the Upper Central Plain, Thailand
The Upper Central Plain of Thailand, where farmers depended on both surface water and groundwater. Water allocated from the Bhumibol and Sirikit Dams are limited and caused water shortage in the dry years. Most farmers turn to use groundwater to supplement irrigation water in the dry years. This study aims to understand the flow budget change of groundwater under climate change scenario. The conjunctive use ratio of surface- as well as groundwater were investigated by field surveys and groundwater flow modeling, using the MODFLOW model to simulate the groundwater movement over the 10 years . The study used the bias-corrected MRI-GCM data to project the future climate conditions (during 2015 -2029 and 2075 - 2089) and assess the impact on flow budget change of groundwater system. The conjunctive use ratio were analyzed from surface water use and flow budget of groundwater system in term of water demand, rainfall, reservoir storage, groundwater recharge, groundwater storage, groundwater pumping. The study shows the flow budget change and conjunctive use ratio of each season and water year in the past and in the future under climate change scenarios.