中文摘要：

＂固定河段挖粗沙＂是水库可行的减淤方式之一。以三峡水库为例,利用水流泥沙数学模型研究挖粗沙后水库的减淤效果及过程。计算结果表明,在三峡回水末端设置约10km长度挖沙段进行挖粗沙（d〉0.1mm）,使水库百年淤积总量由177亿m3降至140亿m3左右。挖沙段集中拦截了入库的大部分粗沙,通过改变河道坡降、流速和挟沙力等水力条件,使库区淤积面与回水面同时降低,减淤效果延伸至整个水库,减淤效率很高。在库区设置固定河段持续清除粗沙是一种高效可靠的水库减淤方式。

英文摘要：

Coarse sediment dredging（CSD） at a fixed basin is an applicable measure of reservoir desiltation.This paper presents a study of CSD process and its effects to reduce deposition in the Three Gorge reservoir by applying a model of unsteady flow and sediment transport.Calculations reveal that by clearing away the coarse sediment from a dredging basin of 10 km long located at the reservoir＇s backwater end,the volume of deposits accumulated during 100 years will be reduced from 17×109 to 14×109m3.A detailed analysis shows that the dredged backwater reach could collect and hold up most of the inflow coarse sediment and the desiltation effect of dredging extends from the dredging location to the whole reservoir through an adjustment process of riverbed slope,flow velocity,sediment transport capacity and deposition distribution.Thus,CSD at a fixed basin is a reliable method of high efficiency in reducing reservoir deposition.