Abstract:In the past 50 years, the sediment yields of the Loess Plateau have changed significantly, due to both natural and human factors. This study analyzes the temporal and spatial variability of sediment yields of the Loess Plateau, and estimates the effect of precipitation variability on sediment yield using the annual sediment yield. Data were collected from 115 hydrological and 276 meteorological stations. The 10 main tributaries of Middle Yellow River show that the annual sediment discharge has decrease over the past 50 years, especially since 1980s. Two periods were compared: one prior to the implementation of soil conservation methods (1956-1969), and one post-implementation (1970-1989). The sediment yield decreased by 44.3%; there are also significant spatial differences between the periods. The most significant decrease was observed the Middle and Lower Wudinghe River, and in the north central Shanxi Province, where sediment yield decreased by more than 40%. A similar pattern of decline was evident for precipitation records; therefore, precipitation variation might play an important role in the decrease in the sediment mobilization from the landscape, and hence, the decrease in sediment yields. However, human activities such as soil conservation and water diversion contributed significantly more to this decline in the sediment yield than the precipitation. It is estimated that 61%-90% of the decrease in sediment yield can be attributed to human activities.