Estimation of Flow of Three Diversions in the Jingjiang River After the Operation of the Three Gorges Reservoir

According to the field data in the last 50 years,reasons for the changes in the flow of the three diversions were analyzed.During 1955—1990,the flow of the three diversions reduced because of the water level drop in the Jingjiang river and the deposition of the three outlets;while during 1999—2004,the three diversions changed little because the water level in the Jingjiang river and the deposition of the three outlets both changed little.After the operation of the three Gorges reser-voir,the sediment discharge of the Yangtze main stream has greatly decreased.Measured data were used to predict the changes of water level in the Jingjiang river if the Three Gorges reservoir is operated for 20 years.Based on this,we esti-mated the scour depth in the three outlets and the changes of the flow of the three diversions if the Three Gorges reservoir is operated for 20 years.Results show that the decrease of medium and high water level is finite in the Jingjiang river,while the riverbed elevation of the three outlets drop largely.So the diversion ratios will not be reduced.