三峡水库蓄水后长江上游水沙变化分析

An Analysis of Changing Characteristics of Runoff and Sediment Transport in Upper Changjiang River after the Impounding of Three Gorges Reservoir

根据三峡水库蓄水前后水沙资料,对长江上游水沙特性进行了分析,结果表明上游水文站近期年径流量变化不大,年输沙量有减小的趋势,三峡入库沙量持续减少,输沙量减少主要集中于汛期,其中北碚、屏山站年输沙量的减小是三峡入库沙量减小的主要原因;清溪场水文站受三峡水库回水影响,流量与含沙量相关关系在汛期时基本一致,枯期时含沙量减小,说明泥沙在上游落淤;上游主要水文站实测悬沙有变细的趋势,其中万县和宜昌站实测悬沙粒径减小幅度较大。

The trend of water flow and sediment change are analyzed based on the observed data of the hydrographic station before and after the impounding of Three Gorges Reservoir.It is shown that the trend of runoff evolvement in upper Changjiang River is not distinct,but the trend of sediment transport decrease is distinct.The incoming sediment of Three Gorges Reservoir decreases constantly and sediment reduction is mainly concentrated in flood seasons,while the reducing sediment of Beibei Station and Pingshan Station are the major reasons.The backwater of Three Gorges Reservoir influences the rating curves of Qinxichang Station,the correlation between water discharge and sand content in flood season is good while sand content decreases in dry seasons,it means that sedimentation occurs in upper Yangtze River.The particle size of suspend load in the main hydrographic stations in upper Changjiang River decreases while the measured suspended load particle size in Wanxian Station and Yichang Station decreases by a big margin.