关键词: 采砂; 河床演变; 水沙条件; 趋势预测; 湘江;

Abstract: Based on the analysis of the characteristics of water and sediment from the upstream and recent evolution of the channel in the typical sand mining area of the main stream of the Xiangjiang River, we forecast the evolution trend of the channel and preliminarily analyze the influence of sand mining activities on the river regime, flood control and waterway, and finally put forward some suggestions.The results show that the average annual runoff(1950～2015) of Xiangtan gauging station was 65.8 billion m3,and the runoff in 2016～2018 decreased as a whole.Over the years(1953～2018),the annual average suspended sediment transport increased and decreased sometimes, but decreased significantly in recent years.In 2017,the median particle size of suspended sediment and bed sediment in the typical cross section of the local river reach in the mining area increased in varying degrees.Recently(from March 2003 to November 2017),in the analyzed river reach, except for the local shoreline, the horizontal position of thalweg line was relatively stable, and the beach and deep groove changed during the different years, showing cumulative erosion.Affected by sand mining, the water and sediment balance of the original river channel was destroyed, and the thalweg of the channel moved to the left.It is predicted that channel is less likely to swing to the right bank, and the river regime and plane shape of the reach will be relatively stable in the future.At present, the channel evolution of the local reach of sand mining is still in the process of adjustment and change, which has not yet had obvious adverse impact on flood control and waterway.The research results are of great significance to the revision of Xiangjiang River sand mining planning and the strengthening of sand mining management in the future.

Key words: sand mining; river bed evolution; flow and sediment condition; trend prediction; Xiangjiang River;