MODELING A RIVER-LAKE INTERACTION SYSTEM IN THE TONLE SAP LAKE AREA

Mekong River-Tonle Sap Lake is a typical river-lake interaction system in a monsoon area. The Tonle Sap Lake (TSL) is the largest freshwater lake in Southeast Asia, and is an important component in lower Mekong River (MR) Basin. Water resource managers are highly concerned about the potential impact of climate change on the MR-TSL hydrological system in the future. Thus, it is necessary to develop a numerical model which can simulate MR-TSL interaction system for the assessment of potential impact of natural climatic variations on hydrological cycle in this area. The main objective of this study was to model a river-lake interaction system for water resource assessment in TSL area. The distinctive feature of this study is to develop an integrated River Lake Water Exchange (RLWE) model and couple it to a grid based distributed hydrological model (YHyM) for MR-TSL system. Using the coupled model, discharge contribution to TSL from tributaries, lake water volume, water exchange between the MR and TSL, and consumptive water use in TSL area were simulated. The potential impact of climate change on TSL hydrological system was also assessed through the application of the coupled model. Several future scenarios were analyzed, and predictions of water budgets within the interaction system under different scenarios were made.