Changes in the Hydrological Regime of Dongting Lake during the Refill Operation of the Three Gorges Reservoir

The Three Gorges Reservoir (TGR) plays an important role in water resource management, and its influence on the downstream flow has attracted much attention. In this work, Dongting Lake was selected as a case study to analyze the influence of the TGR on the hydrological regime. A one-dimensional and two-dimensional (1D and 2D) coupled hydrodynamic model based on Mike simulation modules (MIKE) was constructed for the Yangtze River and Dongting Lake to analyze the hydrological changes induced by the TGR. Hydrological data from 2015 to 2016 were chosen for calibration, and observed data from 2017 were used for validation of the model. The results show that the TGR operation reduced the Jingjiang River inflow and changed the speed of the outflow from Dongting Lake to the Yangtze River during the refill operation period. The methodology for analyzing the influence of the TGR on the hydrological regime using the 1D–2D coupled hydrodynamic model is generic and can thus provide technical support for optimally scheduling the TGR during refill operation.