Distribution and Variation Characteristics of Ultimate Sediment Concentration in the Tributaries of the Middle Yellow River

In this paper, the ultimate sediment concentration in the control area of a hydrological station was defined as the maximum sediment concentration measured by the station in typical tributaries of the middle Yellow River, which reflects the erosion capacity of the control area. The distribution and variation characteristics of annual maximum sediment concentration in typical tributaries of the middle Yellow River are analyzed. The measured maximum sediment concentration in the tributaries of the middle Yellow River is approximately within the range of 700~1500kg/m³, and the annual maximum sediment concentrations in different tributaries are different, with a trend of gradual decrease from north to south. During the natural period (1950-1979), the annual maximum sediment concentration of the same tributary did not change much. In the 1980s and 1990s, the annual maximum sediment concentration of each tributary decreased, but not by much. Since 2000, the annual maximum sand concentration in each tributary has decreased significantly. The preliminary analysis shows that: in 1980s and 1990s, the decrease of annual maximum sand concentration is mainly due to the function of silt dam; since 2000, it is mainly due to the significant improvement of surface vegetation in the basin, and the weakening of slope erosion and the weakening of gully erosion caused by the decrease of gully flow.