长江上游水流挟沙力与含沙量比值的变化规律北大核心CSCD

水流挟沙能力与含沙量的相对大小是判断河床冲淤的主要指标。本文基于长江上游主要干支流控制性水文站2010—2020年实测水沙资料,采用张瑞瑾水流挟沙力公式,分别计算了各站的水流挟沙力,在此基础上分析了水流挟沙力与含沙量比值(S^(*)/S)的变化规律。结果表明:除部分位于库区水文站小流量时S*/S小于1外,其余S^(*)/S均大于1,表明长江上游河道总体呈不饱和输沙状态;除金沙江向家坝站外,其余各站S^(*)/S随流量均呈先增加后减少的趋势,存在一个极大值点;2013年以后长江干流朱沱站和寸滩站同一流量条件下S^(*)/S较2013年前偏大,而沱江富顺站和涪江小河坝站2013年以后同一流量条件下S^(*)/S较2013年前偏小。研究成果对认识山区河流输沙特性、提升河道冲淤演变的预测能力等具有一定的参考价值。

Comparison of sediment carrying capacity to sediment concentration in upper reaches of Yangtze River

The ratio of the sediment carrying capacity (S*) of a river flow to its local sediment concentration (S) serves as a direct indicator of topographic change in riverbed. We have collected the field data of the upper Yangtze measured at its major hydrological stations in 2010-2020, and conducted an analysis of the ratio S*/S. The results show that with a few exceptions, the carrying capacity generally exceeded local sediment concentration, and S*/S presented a first-increase-then-decrease pattern of variation with flow discharge. This pattern is closely related to upstream dam operation and earthquakes－e.g., impoundment of the Xiluodu and Xiangjiaba reservoirs since 2013 led to an increase in S*/S at the same flow discharge, while a decrease in S*/S has been observed at the Xiaoheba and Fushun stations in recent years due to the gradually reducing effect of earthquakes. The findings in this study provide a new insight for understanding sediment transport and promoting channel regulation in mountainous rivers.