Abstract

This paper analyzes the change rules of flow and sediment diversion through three outlets along Jingjiang river into Dongting lake in the past 50 years, and studies their decline reasons from various aspects of Dongting lake’s evolution, systematic cut-offs of lower Jingjiang river and impoundment of Gezhouba and Three Gorges reservoirs as well as water level rising at Chenglingji hydrometric station etc. Result indicates that the regulation of change in relationship between Yangtze river and Dongting lake and the sediment deposition in floodway channels of three outlets are the primary causes of decline in river networks at south bank of Jingjiang river; cut-offs of lower Jingjiang river, reduction in area and volume of Dongting lake as well as the impoundment of Gezhouba and Three Gorges reservoirs speed up its decline process.

Keywords: river networks at south bank of Jingjiang river, river evolution, decline mechanism