长江上游近期水沙变化特点及其趋势分析

Analysis of recent changing characteristics and tendency runoff and sediment transport in the upper reach of Yangtze River

对长江上游主要控制站水沙量进行了统计分析。近期长江上游水沙变化特点主要表现为:与1990年前相比,1991-2002年宜昌站年均减少沙量约1 3亿t;金沙江屏山站年均增加沙量约0 35亿t,其占宜昌站的百分数由51 8%增加到71 9%;嘉陵江北碚站年均减少沙量约0 985亿t,占宜昌站的百分数由25 7%减小至9 1%。采用滑动平均法以及Spearman秩次相关检验和线性回归检验等方法,对屏山、北碚和宜昌等3站水沙变化趋势进行了分析,分析结果表明:宜昌站径流量无趋势性变化,但输沙量有减小趋势;北碚站水沙减小趋势均较为明显;屏山站径流量无趋势变化,但输沙量有一定的增大趋势。另外还对影响长江上游水沙变化的降水量、水土保持措施、水库拦沙以及人类活动增沙等主要因素进行了分析。

This paper statistically analyses the runoff and sediment transport of the major stations in the upper reaches of Yangtze River. Compared with the annual runoff and sediment transport before 1990, there were three major changes of annual sediment transport in the term of 1991-2002: the Yichang station decreased about 1.3×10~8t; the Pingshan station at the Jinsha River increased about 0.35×10~8t, and the percentage (compared with Yichang station) also increased from 51.8% to 71.9%; and the Beibei station increased about 0.985×10~8t, and the percentage also decreased from 25.7% to 9.1%. Through several non-parameter statistical methods such as the moving average check, the Spearman order correlativity check and the linear regression check, the paper concludes that the trend of runoff evolvement at the Pingshan station is not distinct, and nor is that of the sediment transport increased; but trends of the runoff and sediment transport decreased are very distinct; the trend of runoff evolvement at the Yichang station is not distinct, and the trend of sediment transport increased is distinct. The major factors correlated with the runoff and sediment transport changes such as the rainfall, water-and-soil conservation measures, reservoir trap and artificial inducements of soil etc. are also introduced.