黄河中游水保前后河流含沙量变化

Sediment Concentration Variation in the Tributaires of the Middle Yellow River

以黄河中游河口—龙门区间的主要支流为例,利用其近30年的水文测验资料,采用方差分析,对不同流域地貌条件下的河流水保前后含沙量的变化情况进行了分析.分析结果表明,黄土丘陵区河流含沙量受水土保持的影响显著,反映水保前后含沙量变化的特征值F与流域水保面积有着良好的线性关系,利用这一关系可以推求出黄土丘陵区河流水保面积达到流域水土流失面积20%以上时,河流含沙量会显著减少.对于流域内同时存在沙砾丘陵区与黄土丘陵区的河流,水土保持对河流含沙量的影响不大.

Not only sediment in rivers but also discharge are reduced due to soil conservation. In order to compare the effect of soil conservation on soil erosion and the effect on discharge, using measured data in nearly 30 years, We ananlyzed the sediment concentration variation in the main tributaries in the Middle Yellow River with anova. It is revealed that sediment concentration of the tributaires in the loess hilly area is affected by soil conservation obviously. The facotr F in anova, which reflected the character of sediment concentration variation before and after soil conservation, is related to the soil conservation area closely. With this relation, the critical soil conservation area is deduced to be 20% of the soil erosion area in the basin. However, such relation does not exist in the rivers passing through both loess and sand-gravle hilly area. This may be due to the coupling relation between erosion in loess hilly area and sand-gravel hilly area, which can counteract the effect of soil conservation.