Study On Joint Ecological Optimal Operation Of Longtan - Yantan Hydropower Station

Cascade hydropower stations can bring about safer flood protection, more power generation benefit and higher quality water supply, at the same time, its powerful ability of regulating runoff also makes unprecedented pressure on the natural ecosystem of the river. The fragmentation of rivers and the homogenization of runoff process have stress effect on the environment inevitably, such as to interfere with the original ecological processes in the basin and the habitat biology depending on in varying degrees.In order to use the water resources sustainably, we need to calculate the appropriate ecological water demand and flood pulse frequency for specific rivers, and choose one or several reservoirs who have enough regulating capability on the whole basin, considering the downstream ecological water demand, carry out united ecological operation research. So we can relieve or partly eliminate the negative impact on ecology because of damming activities.Based on this situation, this paper selects the Longtan-Yantan cascade reservoirs on the Hongshui river as the research object. Through the Mann-Kendall method and complex Morlet wavelet analysis method, the paper analyze the characteristic of river runoff on Hongshui river, and make sure the ecological stress starting from2004. We analyze the degree of runoff change after stress happened by RVA method, results show that the degree of hydrologic alteration about Hongshui river has reached58.47%, which belong to moderate change. Using the monthly minimum ecological flow and appropriate frequency flow, considering the four major Chinese carps special demand for the flood pulse, we carry out research on discharge process of cascade reservoirs from the ecological base flow and flood pulse. According to different ecological constraint conditions, the paper set up four kinds of scheduling scheme:the basic engineering constraints scheme, minimum ecological flow constraints scheme, appropriate frequency ecological flow constraints scheme, artificial peak-minimum ecological flow constraint scheme; Meanwhile according to different scale of flood peak, artificial peak scheme is subdivided into three kinds sub-program, we contrast and analyze the loss of power generation benefit because of ecological operation schemes. The result shows:setting higher ecological flows simply will reduce power generation benefit seriously, and there are not enough water and adjustment ability in dry year; The artificial peak-minimum ecological dispatching operation model can make up the downstream specific biology demand for water and form. The paper offers a new way for research on restoring the river ecological.