Study On The Estimation And Regulation Of Ecological Flow In The Main Stream Of Qingjiang River

With the expansion of population and increasing social demands,the increasing exploitation of natural resources by human society has led to the weakening of the overall ecological function of rivers and the reduction of biodiversity.As an important tributary of the Yangtze River in Hubei Province,second only to the Han River,the Qingjiang River has long had a high degree of hydraulic development and is one of the first key river and lake ecological flow management targets of the Ministry of Water Resources.Issues such as how to determine the appropriate amount of water required by the ecosystem,and how to compensate and mitigate the adverse effects of reservoirs,dams and other water projects on the ecosystem need to be studied in depth.For this reason This paper analyzes the changes of hydrological situation in the main stream of Qingjiang River on the basis of summarizing the progress of domestic and international research on ecological flow and ecological scheduling,reasonably determines the ecological flow threshold range of each river section in the main stream of Qingjiang River,and proposes a scientific ecological scheduling scheme,and the main conclusions of the paper are as follows:(1)The hydrological changes in the main stream of Qingjiang River were analyzed.Based on the IHA software platform,33 hydrological change indicators and their hydrological change degree were analyzed at the Gao Bazhou hydrological station using the range of variation method to determine the change degree of hydrological situation at different construction stages.The results show that the water construction has a significant impact on the rate and frequency of flow change and the annual average extreme flow,and the reservoir storage and replenishment effect is obvious.(2)The ecological flow process line containing the upper and lower tolerance limits and the upper and lower appropriate flow limits was proposed,and the ecological flow thresholds of typical cross-sections were determined scientifically and reasonably.The ecological flow rate was calculated using the flow rate method with reference to the life habits of the fish,and the appropriate ecological flow rate range of the typical section was determined.Based on Shelford’s Law of Tolerance,the minimum ecological flow rate is proposed as the minimum ecological flow rate,the maximum ecological flow rate is proposed as the maximum ecological flow rate,and the upper and lower ecological flow rates are proposed as the threshold ecological flow rate indicators,and the ecological flow process line reflecting the dynamic changes of ecological flow rate is drawn to scientifically determine the threshold ecological flow rate range.(3)The ecological flow surplus and deficit of the Qingjiang River basin was analyzed.Based on the historical flow results of typical cross-sections,typical representative years reflecting the characteristics of abundance,flatness and depletion were identified.Based on the ecological flow process line,the ecological flow surplus and deficit analysis was carried out to determine the typical months with ecological deficits under different level years.(4)The ecological scheduling measures for the main stream of Qingjiang River were scientifically proposed.With the goal of no ecological flow deficit,the ecological water replenishment scheduling plan is formulated according to the flow process under three different levels of years: abundant,flat and dry,so as to replenish ecological water through reservoir scheduling and guarantee the basic survival and spawning and nursery water needs of downstream fish.