Hydrological Response and Ecological Flow Optimization in Water Diversion Area of Inter-Basin Water Diversion Project

Abstract To quantify the impact of inter-basin water transfer project on hydrological and ecological environment of downstream river, taking Hanjiang-to-Weihe inter-basin water transfer project in the initial operation period for example, hydrological response and ecological flow optimization in water diversion area after water transfer are discussed in this paper. Firstly, Multi-year reservoir operation model of "Sanhekou" is established by MIKE BASIN. Hydrological indicators system construct by Indicators of Hydrologic Alteration (IHA) and Range of Variability Approach (RVA). Then, verify change degree of hydrologic response before and after the reservoir is built. Moreover, 33 hydrological indicators in IHA consist of five groups to quantitatively evaluate the change degree of hydrological indicators. Finally, seven schemes of different ecological flow processes are set, and the optimal scheme is recommended by AHP. Considering ecological flow management, propose improvement measures from both engineering and non-engineering aspects. The results show that: (1) MIKE BASIN simulation results and design results have a high degree of fit, which verifies rationality of the model; (2) The overall hydrological change of the river is 72.91%, and hydrological response of the river lead to highly change; (3) Scheme 6 reduces overall change degree of hydrology to (56.63%) middle change under premise of less impact on economic benefits, recommended Scheme 6 as the optimal scheme. The research results not only provide important guidance and reference for maintenance and protection of ecological functions of rivers, but also the actual operation of reservoirs.