Research on the flow and sediment diversion in the three outlets along Jingjiang River in recent 50 years

The three outlets along the Jingjiang River are the waterways to link the Yangtze River and Dongting Lake.According to the measured data in the past 50 years,the change law of flow and sediment diversion through the three outlets and affecting factors are analyzed.The result shows that the variation rule of flow and sediment diversion through the three outlets is affected by the following four factors,sediment deposition in the channel of the three outlets,the river regime regulation at the entrance of the three outlets,riverbed scouring in the Jingjiang reach and the deposition and shrinkage of Dongting Lake.Since the 1950s,the diverted flow and sediment in the three outlets was obviously decreased.From 1956 to 1966,the flow and sediment diversion ratios are 29% and 35% respectively,whereas from 1999 to 2002,they are decreased to 14% and 16%,meanwhile the no-flow days increase accordingly.After the impoundment of the TGR,the flow and sediment diversion ratios are 12% and 18% respectively.Comparing with the period from 1981 to 2002,there is no obvious change of flow and sediment diversion in the three outlets,but no-flow days at Shadaoguan station of Songzi outlet increases.