Before 2000, the value of the matching index of maximum flow increased slightly; however, due to the regulation of the TGD on the peak discharge, the index decreased significantly after 2003 (Fig. 5a). In addition, the value matching index of maximum flow increased before 2003, and the indexes were basically greater than 1.5, which shows that the flow discharge meets the eco-environmental water demand. However, after 2003, the value of the matching index of the minimum flow increased significantly because of the regulation of the TGD on the runoff process. The values of this index for the Shashi and Jianli hydrological stations are twice as large as they were before 2003 (Fig. 5b), showing that dam construction has certain benefits for the ecological connection of the channels downstream of the reservoir.