Effects of large-scale hydropower reservoirs on sediment loads in Upper Yangtze River and its major tributaries
The mechanics of trapping sediments and detaining floods to reduce flood discharges and sediment-carrying capacity by large-scale reservoirs on main streams is illustrated. Three patterns of sediment yield variation with distance and time in the river channels below reservoirs under conditions of little, limited and large sediment recharge from the downstream watershed are shown in this paper. By analyses of runoff and sediment yield changes after construction of large-scale reservoirs on main streams, it is suggested that construction of those reservoirs was an important driving force of sediment yield reductions since 1990s in the Jinsha and Jialing Rivers and since 1980s in the Wujiang River as well as of sediment load fluctuation since 1970s in the Minjiang River. The annual sediment yield during the period of 1992 -2002 decreased by 28. 2% of the yield during the period of 1956 - 1992 and the reduction was mainly contributed by the sediment yield reductions of the Jialing and Jinsha Rivers since 1998. The annual sediment yield at Yichang station during the period of 2003 - 2007 decreased by 82. 2% of the yield during the period of 1992 - 2002 and the rapid reduction since 2003 was no doubt caused by the Three Gorges Reservoir.
国家科技期刊平台
NSTL
万方数据
维普
