乌江流域水沙变化特性及其原因分析

Analysis on variation characteristics and influencing factors of runoff and sediment in the Wujiang River basin

乌江流域是三峡入库水沙来源之一,近年来水沙特性发生了明显变化。1980-2004年与1979年前相比,武隆站年均径流量变化不大,但悬移质输沙量减少了1 140万t,减幅35%。乌江渡电站建成后,乌江干流各站水沙关系均发生显著变化,同径流量下输沙量大幅度减小。水利工程拦沙是武隆站输沙量减少的主要因素,乌江上游东风、普定和乌江渡等电站年均拦沙量为1 500万t左右,导致武隆站输沙量减小约1 030万t。随着乌江干流大型水电站的陆续兴建,流域输沙量在未来一段时期将进一步减小。

The Wujiang River basin is one of the main sources of the incoming runoff and sediment to the Three Gorges Reservoir. Great changes have taken place in the runoff and sediment characteristics in recent years in the basin. Compared with that before the year of 1979, the annual-averaged runoff during the period from 1980 to 2004 at Wulong station changes little, while the suspended load has decreased by 11.40 million tons or 35 % . Since Wujiangdu hydro-power station completed, great changes in the relation between runoff and sediment at each station in the mainstream have happened, and the sediment load at the same runoff level has decreased sharply. The sediment detention by hydraulic structures is the main factor to the decrease of sediment load at Wulong station. The annum average sediment detained by the hydro-projects including Dongfeng and Puding and Wujiangdu in the upper reach of the Wujiang River is about 15.00 million tons. The decrease of sediment load at Wulong station is about 10.30 million tons. With the construction of large-scale hydro-projects in the mainstream of Wujiang River, the sediment load in the basin will decrease obviously in the future.