Integrated Modeling of Water Supply and Demand Under Climate Change Impacts and Management Options in Tributary Basin of Tonle Sap Lake, Cambodia

Abstract

An integrated modeling approach analyzing water demand and supply balances under management options in a river basin is essential for the management and adaptive measures of water resources in the future. This study evaluated the impacts of climate change on the hydrological regime by predicting the change in both monthly and seasonal streamflow, and identified water supply and demand relations under supply management options and environmental flow maintenance. To reach a better understanding of the consequences of possible climate change scenarios and adaptive management options on water supply, an integrated modeling approach was conducted by using the soil and water assessment tool (SWAT) and water evaluation and planning model (WEAP). Future scenarios were developed for the future period: 2060s (2051–2070), using an ensemble of three general circulation model (GCM) simulations: GFDL-CM3, GISS-E2-R-CC, and IPSL-CM5A-MR, driven by the climate projection for representative concentration pathways (RCPs): 6.0 (medium emission scenario). The results indicated that, firstly, the future streamflow will decrease, resulting in a decline of future water availability. Secondly, water supply under natural flow conditions would support 46,167 ha of irrigation schemes and the water shortages will be more noticeable when environmental flow maintenance was considered. The study concludes that reservoir construction would be necessary for agriculture mitigation and adaptation to climate change. Furthermore, the water resources management options considering both supply and demand management are more effective and useful than supply management only, particularly in dealing with climate change impacts.