Research on calculation methods of instream ecological flows

In this paper, through review analyses of the existing methods calculating instream ecological flow, the monthly minimum flow calculation method and monthly frequency calculation method were applied to the Yi-Luo River, located in Northern China; what´s more, some proposals were made to improve ecological flow calculation for rivers of middle-size in Northern China: the variable continuous period method and the monthly second-minimum flow method to calculate the minimum ecological flow; the monthly second-maximum flow method and the upper bound reference method to calculate the maximum ecological flow, and the synthesis method of monthly frequency calculation to determine the optimal ecological flow. Results show that the ecological flow calculated by these improved methods is favorable to the ecological protection of rivers; the output will be helpful for water resource protection and river management.