三峡水库蓄水前后大通水文站水沙特性变化

近年来,受人类活动和气候变化等因素的影响,长江流域的来水来沙特性发生了一些变化。以大通水文站为例,选取1986~2012年的实测水沙资料,分析了水沙关系特性及悬沙中值粒径、悬沙颗粒组成变化规律。结果表明,月均流量与输沙率变化过程具有良好的一致性,且存在着输沙率峰值超前或滞后于流量峰值的现象;三峡水库蓄水后,大通水文站的水文泥沙特性发生了明显变化,洪季泥沙中值粒径大于枯季,汛初流量增大阶段泥沙粗于汛末流量减小阶段,多年平均中值粒径基本不变,但泥沙有逐年变粗的趋势。

Variation on Characteristics of Runoff and Sediment Discharge of Datong Hydrological Station before and after Impoundment of Three Gorges Reservoir

In recent years, characteristics of runoff and sediment discharge of the Yangtze River Basin have been changed because of many factors, such as human activity and climate change etc. Selecting the measured hydrological data of Datong Hydrologic Station from 1986 to 2012, the relationship between runoff and sediment discharge and the change rules of suspended sediment median particle and variation of particle composition are analyzed. The results show that the changing process has a good consistency of monthly mean runoff and sediment discharge, and it exists the phenomenon of sediment peak lead or lag the runoff peak; after impoundment of Three Gorges Reservoir, it changed obviously of the characteristics of runoff and sediment discharge; median particle in lood season is larger than that in dry season; sediment during the stage of runoff raising (initial flood stage) is thicker than that during the stage of runoff decreasing (final flood stage); although the multi-year mean median particle has not changed basically, it appears the tendency that sediment is thicker year by year.