ABSTRACT

The number of reservoirs worldwide increases annually, and there are growing concerns regarding their potential effects on runoff and baseflow. In this study, the impact of the recently constructed Chaersen Reservoir on downstream baseflow recession is analysed using the pre–post comparison method. Additionally, the potential causes of these effects are investigated. Reservoir construction is found to cause the baseflow at the recession stage to increase by a relatively constant value (approximately 1 m³/s), which makes the log(−dQ/dt) vs. log(Q) points at the low-flow stage shift to the right. This eventually results in a decrease of ~70% in recession coefficient a and an increase of ~27% in coefficient b. Consequently, the master recession curve and storage–discharge curve deviate significantly from those before construction. Finally, a baseflow recession analysis strategy suitable for a basin with reservoirs is proposed; it ensures that recession coefficients (a, b) agree well with practical values.