Impacts of Upstream Reservoirs on Flow Pattern Changes at the Kratie Hydrological Station, Mekong River Basin

This study utilized the innovative trend analysis method, the Pettitt test, and reservoir development data to investigate the effects of upstream reservoir development on the flow regime at the Kratie hydrological station in Phom Penh, Cambodia. Kratie hydrological station serves as the outflow of the Mekong Basin (MKD) before it flows into the Mekong Delta (MKD). The Pettitt test identified changes in the statistical characteristics of the mean water level time series in 1994, and for the minimum and maximum water levels, the changes were detected in 1999. The change point occurred sooner compared with the dam boom time in 2010. From 1973 to 2018, the minimum and mean water levels increased by 3.95 cm/yr and 2.16 cm/yr, respectively, and the maximum water level slightly decreased by −0.04 cm/yr. In the subperiod from 2000 to 2022, the minimum water level trend in increased slower than the full period from 1973 to 2022 and the maximum water level decreased slower than the full period from 1973 to 2022. The result showed that the driest time shifted one month sooner to compared with the pre-dam period.