中文摘要：

三峡水库蓄水后，改变了下游来水来沙条件，河床演变也相应发生变化．长江中游窑监水道属典型的弯曲分汉河型，在分析三峡蓄水运用前后河床演变的基础上，采用二维水沙数学模型预测了三峡工程蓄水运用后20a河床演变趋势．计算表明，窑监河段主流仍保持在乌龟洲右汊，主支汊的河势没有发生变化，虽然整个河段呈冲刷趋势，但出浅碍航段航深随着枯水位降落有减小的趋势．在对历史演变分析及演变趋势预测的基础上，利用建立的数学模型研究了航道整治方案．

英文摘要：

Owing to the impoundment of the Three Gorges project （TGP）, water and sediment conditions, as well as the evolution process, in the downstream of the dam have been changed. The Yaojian reach in the middle Yangtze River is chosen as a typical example of meandering and bifurcated channels. A 2D flow-sediment mathematical model of the Yaojian reach is developed in the study. The bed erosion and deposition in the following 20 years after the impoundment of TGP are calculated and analyzed according to the historical data. The results show that the Yaojian reach will be scoured, and the main stream is still in the right branch. Although the main tendency is erosion, the low water level in bends will still decrease. Therefore, the navigation depth in the inlet of the right branch will also decrease. A series of projects such as groins and fishbone dams are going to be built to improve the navigation conditions. The 2D model is used to study the effect of these proposed projects.