Analysis of Scouring and Silting Changes in the Middle and Lower Reaches of the Yangtze River after the Three Gorges Project Operation

Abstract

The annual runoff of the middle and lower reaches of the Yangtze River has little change before and after the Three Gorges Project is put into operation, but the annual distribution of runoff has changed, and the sediment discharge of the reach has fallen in a cliff-like manner. The application of the Three Gorges Project has changed the scouring and silting situation of the main stream and the two lakes, making them change from silting to scouring direction, causing the water level of the rivers and lakes to drop. The changes of scouring and silting conditions, flow velocity, water depth and water level have a certain impact on the survival and reproduction of the four major domestic fish, porpoise and waterfowl. In order to protect the fragile aquatic ecosystem from the adverse effects of the operation of the Three Gorges Project, this paper puts forward three suggestions, namely, the delimitation of protected areas of top priority, the spatial management and control of river and lake shorelines, and the ecological scheduling, which is of great significance to the scientific decision-making of the water administrative department in the process of protection of the Yangtze River.