Abstract

The Wujiang River basin is one of the main sources of the incoming runoff and sediment in the Three Gorges Project reservoir. Great changes have taken place in the runoff and sediment characteristic in recent years in the basin. Compared with that before the year of 1979, the annual average runoff during the period from 1980 to 2004 at Wulong station changes little, while the suspended load discharge has decreased 11.40 million ton, by 25 percent. According to analysis result, the average decrease in annual sediment discharge is about 15.10 million tons at Wujiangdu station in the upper reaches of the Wujiang River, and 1.40 million tons in the section from Wujiangdu to Sinan, and the annual increase of incoming sediment discharge is about 5.00 million tons in the lower reaches of the Wujiang River; Since Wujiangdu hydro-plant completed, great changes in the relation between runoff and sediment at each station in the mainstream has happened, and the sediment discharge at the same runoff level have decreased sharply. The sediment detention of hydraulic structures is the main factor to the decrease of sediment discharge at Wulong station, and the average of annual detained sediment is about 15.00 million tons at the hydro-plants including Dongfeng and Puding and Wujiangdu in the upper reaches of the Wujiang River, as a result, the decrease of sediment discharge at Wulong station is about 10.30 million tons.

Keywords: Wujiang River basin, Runoff and sediment variation characteristic analysis, Quantitative analysis on contribution of influence factors