Research On The Influence Of Cascade Hydropower Development On The Eco-hydrological Regimes Of The Yangtze River

With the rapid development of national economy,the demand for power industry and demand have increased sharply,so the contradiction between supply and demand of water resources has been further intensified.The water supply of reservoir project is the effective measure to alleviate the contradiction between supply and demand of water resources.The construction of Cascade reservoirs have a significant impact on the global water environmental system,especially changed the physical features of rivers and hydrological regime,and caused the degeneration of ecological system,and the risk of speciesdegeneration or extinction.This thesis is provided by the surface of the State Natural Science Fundprojects named ?Research on the accumulation effect and regulation mechanism of important fish habitat in middle reaches of Yangtze Rivers?.The change of the eco-hydrological regimes were analyzed about cascade hydropower project on Yangtze Rivers,generated the recommended environment with ecological target and critical period and the parameters of environmentflow.At last restoration of important biological measure were put forward.The research results mainly include the following aspects:(1)Described the concept and theory of environmental flow and cumulative effectof hydropower cascade development,expounded connection between ecological system of river and hydrologybased on river ecological system theory,summarized the characteristics and calculation methods of environmental flow,and set up the cumulative effect theory framework of the hydropower cascade development.Furthermore cumulative impact of hydropower cascade development was analyzed for biological and non-biological.(2)Tendency and mutability of the daily runoff data was analyzed with the method included mann kendall method,the cumulative departure method slide test and T test,which from hydrologic station including Pin shan,Cun tan,Yi chang,Han kou,Da tong in Yangtze Rives.The hydrological change degree for five group hydrological index and integral degree would be calculated by IHA method and RVA method.At last the impact of cascade hydropower development on biodiversity would be test with SI index method.(3)Non-parametric method was analyzed the runoff changes of hydrological station in Yangtze Rivers.And calculate the environmental flow index by IHA-EFCS method for meeting ecological needs.Generate the recommended environment flow with ecological target and critical period and the parameters of environment flow by HEC-RPT.(4)Taking biological conservation measures from the perspective of engineering,non-engineering and management measures.The engineering measures include the construction of integrated fishing facilities,habitat protection measures and the construction of stratified water intake.The non-engineering measures include artificial proliferation,real-time monitoring and evaluation.Management measures include adaptive management of environment flow,ecological operation,fishery measures and legislation.These measures can weaken or eliminate the environment impact brought by the hydropower cascade development and prevent the river ecosystem degradation and benefit management of water resources.