河流输沙量变化的主要驱动因素

Key drivers of changes in sediment loads of rivers

鉴于河流输沙量的大小和变化对河流系统的功能发挥具有重要意义,且河流输沙量的变化受多种因素驱动,在总结近些年我国河流输沙量变化研究的基础上,分析河流输沙量变化的主要驱动因素。认为我国主要河流除松花江多年水沙量无明显趋势性变化外,其他河流的年输沙量均呈明显下降趋势,主要河流总入海输沙量从1955—1968年的20.3亿t/a降至1997—2010年的5.0亿t/a。研究表明:大坝建设、水土保持措施、流域扰动、河道采砂和气候变化等是输沙量变化的主要驱动因素;长江流域修建大量水库是长江入海沙量降低的主要驱动因素;水土保持措施是黄河入海沙量大幅降低的主要驱动因素之一;流域扰动为澜沧江清盛站输沙量的降低幅度远低于嘎旧站的原因;农业增产减沙可能是淮河入海沙量降低的主要驱动因素;珠江输沙量的降低受到河道采砂的影响;海河流域气候变化是海河诸河输沙量大幅降低的主要驱动因素之一。

The magnitude and variation of the sediment loads transported by rivers are of important significance to the functioning of river system, and changes in sediment loads of rivers are driven by numerous factors. In this paper, key drivers of changes in sediment loads of rivers in China are analyzed by reviewing recent publications of studies on changes in sediment loads. It can be concluded that nearly all of the major rivers in China exhibit an apparent decline in annual sediment loads except for the Songhua River, which presents no clear tendency of changes in runoff and sediment loads. The total annual sediment loads of major rivers transported to the coasts in China decreased from 2. 03 billion t/ a during the period of 1955 to 1968 to 0.50 billion t/a during the period of 1997 to 2010. The primary drivers of changes in the sediment loads of rivers are dam construction, soil and water conservation measure, catchment disturbance, sand mining and climate change. Case studies for rivers in China show the following： construction of a large number of reservoirs in the Yangtze River basin is the primary driver of the reduction of the sediment load of the Yangtze River; soil and water conservation measure is one of the key drivers of the sharp decline in the sediment load of the Yellow River; the catchment disturbance explains why the reduction of the sediment load of ChiangSaen Station was much lower than that of Gajiu Station on the Lancang-Mekong River; the decreasing sediment load resulting from the growth of agricultural production may be the main driver of the sediment reduction of the Huaihe River; the decrease in the sediment load of the Pearl River was influenced by sand mining activities; and climate change in the Haihe River Basin is one of the key drivers of the great reduction of the sediment load of the Haihe River.