Impact on Dongting Lake channel caused by the change of flow and sediment environment after Three Gorges Project impoundment
摘要
The change of river-lake relation is one of the most important factors affecting the flow and sediment environment in the Dongting Lake area. This has a great influence on the safety and development of lake shipping. On the basis of the hydrological and topographical field data,this paper studies the variation in the characteristics of the water-silt environment and then analyzes its influence on the lake channel. The following results were observed that after the project impoundment: ① The mean monthly discharge in dry seasons tends to decrease,the siltation in the lake area slows down and even scours,the low water level at the lake outlet rises to a certain extent,the water surface gradient in the lake tends to decrease; ② The decrease of incoming sediment causes the channel incision,and the rise of low water level at the lake outlet increases the channel water level,the channel is therefore deepened. The river-lake relation is overall positive factor for the lake channel and the benefits for the Xiangjiang channel are more than that for the Kaihu channel.