Analysis on characteristics of runoff and sediment of Zhangjiashan hydrological station and case study for Jinghe river

For reasonable evaluation and use of water resources of sediment-laden river, based on precipitation, runoff, sediment discharge and concentration data of Zhangjiashan Hydrological Station from 1956 to 2009, this paper analyses the variations of runoff and sediment of Zhangjiashan Station. The average characteristic value for many years of each series show that uniformity coefficient of sediment discharge is the largest, sediment discharge in July and August accounts for 81% of the annual total; Precipitation, runoff mainly concentrate in July and September. Statistics of annual average eigenvalue for sub-periods of precipitation, runoff, sediment discharge and concentration are given. The first three items are all in a decreasing trend, the average for sub-periods of sediment concentration fluctuates. Mann-kendall rank correlation test results show that test U-values of annual precipitation, runoff and sediment discharge are −2.39, −4.45, −3.36, all greater than 0.05 confidence level, which indicates that each has significant decrease trend. Period mean of sediment transport modulus reduces, period mean of incoming sediment coefficient increases. Grey correlation analysis and double cumulative curve show runoff and sediment discharge, precipitation all have good correlations, the association degree of the runoff and sediment load is 0.64, slightly larger than that of the runoff and precipitation of 0.62. Finally, this paper discusses the sediment gate project of the headworks in Jinghui irrigation district. The conclusion is that the reasonable limit of sediment is 15%, and the suitable sand excretion flow is 200 m3/s. The results can provide a reference for water project design of headworks of Jinghui irrigation district.