Analysis on decrease trend of water diversion quantity of four outlets of the Jingjiang River

The water diversion variation of 4 outlets of the Jingjiang River will directly influence the relation of the Yangtze Rive and the Dongting Lake.According to historical data and the measured data,the water diversion variation of 4 outlets of the Jingjiang River is analyzed.The analysis results show the water diversion quantity of 4 outlets decreases all the the time,at present,the diversion discharge is only 13% of the Yangtze River′s discharge.The main causes of water diversion decrease are :① due to sediment silting,the diversion river stretches more longer;② due to river channel silting,the river cross-section area reduces;③ due to river cut-off of the Lower Jingjiang River,the discharge of the Yangtze River increases;④ due to TGP impoundment and operation,the flood peak of the Yangtze River is cut off.The water diversion quantity of 4 outlets will decrease further,this will result in quick change of the River and the Lake relation,and then disturbing the layout of flood control system,influencing the planning and design of comprehensive harnessing of the River,the Lake,and the river channel.For these reasons,it is suggested that to strengthening prototype observation and scientific research,finding out the basic law and the inevitable tendency of water diversion evolution to provide reliable data for new planning of the River and the Lake regulation.