The Effection of the Annual Maximum Sediment Concentration Reducing on Sediment Variation in the Yellow River

The problem of sediment is a significant issue in river harnessing, which is more prominent in the Yellow River, affecting the strategic decision-making of the Yellow River and the success and benefits of the project. the data with systematic hydrological observation of 68 years from 1950 to 2017 in the Yellow River are used to study the process and characteristics of runoff and sediment variation in the Yellow River. The results show that the measured runoff in the current periodis reduced by 90% compared to the base period and the measured sediment discharge is reduced by 44%. The reduction of the measured sediment discharge is almost concentrated in the Midstream Toudaoguai - the Tongguan section, which accounted for 92% above Tongguan hydrologic station. The reduction of measured runoff is affected by both the upper and middle reaches of the Yellow River, and the reduction of midstream is greater than that of the upstream, which accounted for 42% and 58% respectively. Further analysis of the annual maximum sediment concentration of main tributaries are made, and the results display that the change of the annual maximum sediment concentration is consistent with the change of fractional vegetation cover. The annual maximum sediment concentration of the tributaries changed less before the year of 2000, which indicates that the water conservancy and water conservation engineering measures can reduce the sediment discharge rather than the erosion intensity of each river basin.. After the year of 2000, the annual maximum sediment concentration of the tributaries decreased significantly indicating that the method of increasing fractional vegetation coverage, as a erosion reduction pattern, can reduce the sediment discharge as well as the erosion intensity.