Hydrological changes along the Jing River and its causal analysis

The hydrological response of rivers to upstream reservoir regulation is one of the increasingly important research issues of watershed management. In this study, a hydrodynamic coupling model was used to simulate water level and flow processes of the Jing river and diversion flow of three outlets before and after the operation of TGP (Three Gorges Projects). The results indicated that water level and flow of three diversion channels both decreased in flood and dry seasons: the compensation regulation of the TGP was significant to maintain the water level and flow of three diversion outlets in the Jing river, but it also increased zero-flow days in the diversion channels of the Yangtze River. The riverbed erosion of channels in the upper reaches as well as lower reaches caused hydraulic gradient varying so much that it can't be ignored in the water exchange process between the Yangtze and Jing river. This mechanism cooperates with the operation of TGP to change the natural process of the Yangtze-Jing river's hydrologic process. This work provides essential information for future water resources and environmental management of the river-lake system and facilitates the effective flow regulation of dams, which has significant implications not only for the Dongting river-lake system but also the similar lakes and rivers elsewhere.