Analysis of runoff variation characteristics in Yishuhe River Basin

Yishuhe River Basin is located in the northeast of the Yishusi River Basin, with the watershed area of about 18200 km(2). It is necessary to analyze the variety characteristics of runoff in Yishuhe River Basin, and it will provide technical support for flood control and drought relief. Based on the past continuous 60 years' data of runoff measured at 2 hydrometric stations and precipitation at 23 precipitation stations in Yishuhe River Basin, this study analyzed the monthly and annual variation characteristics of the runoff in Yishuhe River Basin using some indexes and methods such as complete regulation coefficient and nonuniformity coefficient, concentration ratio, concentration period, Man-Kendall trend test and mutation detection, and so on. The research results indicate that the distribution of annual runoff in Yishuhe River Basin is uneven, the monthly maximum precipitation occurs in August generally, and the continuous four months' runoff even accounts for 80% of that of the year. The annual runoff shows a decreasing trend with time at Linyi station in Yihe River and Daguanzhuang station in Shuhe River, and the tendency of runoff reduction is significant in Yihe River with an abrupt point happening in 1966 and 2013.