Study Of Three Gorges Reservoir Ecological Operation And Multi-objects Risk Analysis

While the water conservancy project has brought considerable economic benefits for the society,its damming up impact reduces the fluctuation feature of flood,having the unignorable influence on the river ecosystem.Reservoir ecological operation provides a way to mitigate that kind of influences.Reservoir ecological operation restores the natural hydrological regime to repair structure and function of ecosystem in the river upstream and downstream of dam by improving the operation mode of the reservoir and operation facilities reasonably,including river ecological water demand scheduling,simulating flood dispatching,ecological factors scheduling,the sediment control scheduling and prevention of water pollution scheduling,etc,which all are relatively advanced reservoir management methods.Besides,due to many uncertainties,as the important project to manage basin water resource,reservoir faced with all kinds of risks,needing risk analysis to better use water resource and bring benefit to our society.This text based on the improvement of desired flow conditions needed for the four major Chinese carps spawning downstream three Gorges of the Yangtze River,firstly carried out the research from the aspect of flood pulse impact on fish spawning activities,taking index analysis of measured flow data of the yichang gauging station downstream three gorges and doing Mann-Whitney non-parametric significance test to find the indicators that had significant changes such as the flood pulse fluctuation duration,established the reservoir ecological operation multi-objective optimization model to analyse the impact of flood pulse duration extension on power generation.The result showed that appropriate increase of flood fluctuation duration has little effect on power generation,which can be reference for the reservoir scheduling personnel to promote the spawning of four major Chinese carps during flood season.Secondly,this paper discussed the ecological velocity range for the four major Chinese carps during spawning period,combining with the measured profile data,put forward ecological hydraulic radius method based on triangular fuzzy number,calculated suitable ecological flow and its membership function for the growth of the four major Chinese carps.The result can be the flow reference for the three gorges reservoir ecological operation.At last,the paper used @RISK stochastic simulation software,combining with seasonal first-order autoregressive model,simulated the incoming runoff,and used the monte carlo risk analysis method to analyze the three gorges-gezhouba cascade reservoir scheduling flood control risks,and got the optimization solution according to the proposed several irrigation scheduling scheme with Genetic optimization applications,calculated the risk value and efficiency of the scheme to compare each scheme.