Abstract

The Jingjiang Reach of the Yangtze River is located the lower 100 km of the Three Gorges Project. From view of flood control, it is the most dangerous reach along the Yangtze River. Many shoals distribute on Jiangjiang Reach and they evolve acutely. Evolvement of shoals affects river thalweg tendency towards of downstream, river evolvement and river renovation on Jingjiang Reach in a certain extent in the past fifty years. The change of the main shoals is the concerned focus for sediment experts after impounding water of the Three Gorges Reservoir. Based on the field data in the past fifty years, this paper analyses the relationship between area, length of three typical Shoals and the suspended sediment load concentration, duration of flood, water surface slope and human activities. It indicates that evolvement of the three typical shoals is interrelated nearly with the suspended sediment concentration, duration of flood, water surface slope, riverbed composition and the different shoal has different correlativity. This paper gives the relation formulas for two different typical Shoals and also predicts evolvement tendency of the three shoals after impounding water of the Three Gorges Reservoir according as the correlativity. The conclusions of this paper can provide scientific basis for river evolvement, flood control and river renovation on Jingjiang Reach.

Keywords: study, evolvement, mechanism, shoal, Jingjiang Reach