Alterations in the Water-Level Regime of Tonle Sap Lake

The Tonle Sap Lake (TSL), located in southwestern Mekong Basin, is the largest freshwater lake in Southeast Asia. The water-level regime of the TSL has been changing over the last few decades due to the rapid development of water infrastructures and climate change in the Mekong Basin. This paper makes efforts to quantify the water-level regime alterations of the TSL by analyzing the pre- and post-1991 historical data of daily water levels from Kompong Luong Station. The method of modified indicators of hydrologic alteration was utilized, and the TSL's hydrological behavior was explored further by focusing on the redistribution of hydrology and unfavorable disturbances. The results reveal that the coefficients of variation of most indicators in recent years increase compared with the preimpact years from 1960 to 1990. This demonstrates that the Mekong Basin and TSL are experiencing an increasingly unstable and varied hydrological cycle, which is more susceptible to interference with increased frequency and degree. Moreover, the system may have suffered more unfavorable human interference in dry years and in the dry season. It is expected that the findings in this paper will contribute to the protective development and adaptive management of the Mekong Basin and the TSL in the future.