中文摘要：

受长江上游干支流来水来沙减少、梯级水库蓄水拦沙等多方面因素影响,三峡水库坝下游水沙过程及河道演变发生了明显变化。采用数学模型作为研究手段,开展了三峡水库不同调控方式对坝下游河道演变影响的初步研究。结果表明：不同控泄流量对坝下游河道冲淤总量有一定影响,但影响程度有限,随着水库运用年限的增加,不同控泄方案间的差异有所减小;不同典型河段均表现为河槽冲刷下切、洲滩冲刷萎缩的演变趋势,且随着时间的延长,冲刷强度有所减小,河段的河势总体变化不大,平面形态及深泓摆动幅度较小;控泄洪峰流量减小后,河道演变的趋势变化不大,但大部分河段的河槽冲刷增大,表现为河槽冲深增加和槽宽增大。

英文摘要：

With the impact of the runoff and sediment transportation reduction from trunk stream and tributaries in upper rea- ches as well as the water storage and sediment blocked by upstream cascade reservoirs, the series of runoff and sediment transpor- tation and the evolution of river channel in the lower reaches of TGP dam have changed significantly. The effect of different regu- lation modes of the Three Gorges reservoir on the downstream river channel evolution .is studied by using the numerical model cal- culation. The results show that different discharge would affect the erosion and sediment deposit at a limited extent ; with the ac- cumulation of reservoir operation period, the difference among different discharge schemes would reduce; scouring is expected in all different sections of river channel and shrink is predicted for islands and beaches; however, the scouring would decrease, river regime tends to be stable and the thalweg swing scope become smaller with time; when the flood peak discharge is cut by the res- ervoir operation, the evolution trend of river channel tends to stable, while scouring increase in most parts of the channel appea- ring as the expansion and deepening of the channel.