Research On Ecological Water Level Of Open Lakes: a Case Study Of Poyang Lake

Poyang Lake is the largest freshwater lakes in China and the one of the two largest natural lakes which still has hydrologic connection with the Yangtze River. Poyang Lake also has many international important wetlands and many wild animals perching and multiplying. Studying the cological water level of Poyang Lake has significant scientific meaning for its protection. In this study, six methods including the frequency curve, Qp, natural water level data, annual guarantee rate-setting, lake morphology analysis method and functional method were used to calculate the ecological water level of Poyang Lake. The results showed that the ecological water level from the lowest to the highest were natural water level data method, Qp method, frequency curve method, functional method, annual guarantee rate-setting method, lake morphology analysis method, respectively. Through analyzing the intension and calculation principle of current ecological water level calculation methods, all those results could not meet the ecological requirement of the Poyang Lake, because of the complex hydrological processes of Poyang Lake. It was thought that the health water level of Poyang Lake would be a process curve instead of a stable line.