| Water resources and the series of functions they provide can promote social and economic growth,protect the health of the ecological environment,and benefit the sustainable development of man and nature.However,the development and utilization of water resources by humans in recent decades has changed the natural flow patterns of rivers.The contradiction between water use inside and outside the river has increased sharply,and the amount of water resources in the river and the habitat of aquatic animals and plants have been continuously compressed.This paper relies on the National Natural Science Foundation of China "Research on Fish Ecological Flow Based on the Response Mechanism of Ecology-Habitat-Flow Temporal and Spatial Grouping"(51809239)to evaluate the overall form of ecological flow and its guarantee rate,taking the main stream of the Huai River from Lutaizi to Huainan as study area.The main research results are as follows:(1)Ecology-Habitat-Flow spatiotemporal grouping response mechanism and model construction.Based on the theory of habitat simulation,through the key habitat factors involved in fish ecological process,the response relationship between flow and fish ecological process is studied,and the ecological-habitat-flow grouping response mechanism is revealed.Then analyze the impact of habitat factors on the ecological process of fishes,such as hydrological situation,geographic characteristics,hydraulic conditions,and water environmental quality.Based on the time-space grouping response mechanism of ecology-habitat-flow,a modular simulation model of ecology-habitat-flow is constructed,and suitable overall form of ecological flow(quantity,process and characteristics)corresponding to different stages of fish ecological process are recommended.(2)Establishment of an evaluation system for the overall form of ecological flow guarantee rate.Based on the long series of historical runoff data,combined with the flow duration curve,the relative duration of the ecological flow in the historical runoff sequence is calculated;the connotation of the value,process,and characteristics of the ecological flow is clarified,based on the ecological-habitat-flow modular simulation model.The overall form of ecological flow,an evaluation system for the overall form of ecological flow has been established.Based on the historical flow series and the typical annual flow process,assess the degree of assurance of mid-,long-term and short-term ecological flow.(3)Case analysis and main results.Apply the above method model to the section from Lutaizi to Huainan on the main stream of the Huai River,with the four major home fish as the research target.The results show that during the study period,in addition to the high concentration of chemical oxygen demand,which will have a certain impact on the growth and reproduction of fish,the rest of the water quality needs of the domestic fish in each period of their life history can be met;and the upstream date of domestic fish should not be greater than The flow process of 893m3/s,the spawning and breeding period should have a water stimulus greater than 654m3/s,the juvenile fish feed period should have a high flow greater than 899m3/s at least once,and the ecological needs during the wintering period can be met.The guarantee rates of ecological flow in the flood season and non-flood season of Lutaizi Section from 1956 to 2018 were 91%and 89%,respectively;the guarantee rates of the overall form of ecological flow in wet years,normal years,and dry years were 76%,79%,and 71%respectively.The inter-annual differences in runoff should be adjusted in conjunction with ecological regulation,so as to meet the water demand of the ecosystem as high as possible,so as to ensure the healthy operation of the ecosystem. |
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