The influence of human activity on variations in basin erosion and runoff-sediment relationship of the Yangtze River.

In this article, the effect of reservoir sediment retention is studied by introducing the incoming sediment coefficient, and sediment reduction by reservoir and soil-water conservation is quantitatively calculated in the Yangtze River. Results demonstrate that different human activities, including soil and water conservation, hydro-project construction and over construction, have different impact on the runoff and sediment variation. Moreover, sediment trapping by reservoirs is the main factor, soil and water conservation is an important factor and other human activities such as river sand mining and over construction are secondary factors for the variation of basin erosion and sediment transport in the Yangtze River. In addition, the total annual sediment reduction is 33.64 million tons in typical tributary of the upper Yangtze River, of which the contribution of the reservoir is 21.54 million tons, accounting for 64%, and the contribution of soil-water conservation is nearly 12.1 million tons accounting for 36%. [ABSTRACT FROM AUTHOR]