Spatiotemporal Variability in the Effect of the Water Supply from the Three Gorges Reservoir on Dongting Lake During the Dry Season

To quantitatively calculate the spatiotemporal differences in the effect of the water supply from the Three Gorges Reservoir, three typical falling modes were proposed: falling in advance, uniform falling, and falling at a high water level. Based on a one-dimensional and two-dimensional model coupled hydrodynamic model, the spatial and temporal distributions of the Dongting Lake water level were compared with the ecological water level, which was assessed using a hydrological method, and the power generation of the Three Gorges Hydropower station under different scenarios was also analyzed. The results showed that the water supply effect of the falling in advance and falling at high water level scenarios on the Dongting Lake water level exhibited obvious spatial and temporal heterogeneity, but the effects were mainly concentrated in the northern part of eastern Dongting Lake, whereas limited effects were observed for the southern and western Dongting Lake. In scenario 1 (falling in advance), the water level at Chenglingji increased by 0.12 m on average and power generation was reduced by 0.30%. In scenario 3 (falling at a high water level), the water level at Chenglingji decreased by 0.09 m on average; and power generation increased by 0.28%.