河龙区间近期人类活动减水减沙贡献率分析

分析了河龙区间1997—2006年人类活动对减水减沙的贡献率,探讨了不同流域减沙效益与流域面积的尺度关系。结果表明:①河龙区间近期坡面措施减水减沙贡献率分别为30.2%和54.5%,淤地坝减水减沙贡献率分别为18.0%和27.8%,水利措施减水减沙贡献率分别为46.3%和20.9%,人为新增水土流失减水减沙贡献率分别为-1.8%和-9.7%,封禁治理减水减沙贡献率分别为1.1%和2.2%。②河龙区间近期水利措施减水贡献率最大且不同年代变化不大,坡面措施减沙贡献率最大且上升趋势明显,淤地坝减水减沙贡献率下降趋势明显。水保措施减沙贡献率普遍大于减水贡献率。近期河龙区间水土保持减水减沙的措施主体和构成发生重大变化,林地减水减沙贡献率最大。③随着流域尺度的增大,河龙区间水利水保综合治理的减沙效益呈减小趋势。

Analysis on Contribution Rate of Water and Sediment Reduction by Human Activities at Hekouzhen -Longmen Section in Last Years

The paper analyzed the contribution rate of the human activities effect on river water and sediment reduction of the Hekouzhen-Longmen section from 1997 to 2006 and approached to the sediment reduction benefits in different watersheds and the scale relationship of different drainage areas.The results show that a) the contribution rates of slope measures on water and sediment reduction are 30.2% and 54.5%,the contribution rates of dam are 18.0% and 27.8%,the contribution rates of water conservancy measures are 46.3% and 20.9%,artificially added contribution rates of soil erosion are-1.8% and-9.7% and the contribution rates of new added banning management are 1.1% and 2.2% respectively.b) The maximum contribution measures to reduce water and sediment are water conservancy measures and the trends keep relatively stable in different years and the contribution rate of slope measures is the maximum for sediment reduction and keeps an evident upward trend in different years.The contribution rates of dam decline significantly.The contribution rates of sand and water conservation measures on sediment reduction are generally higher than the contribution on water reduction.The subjects and constitution of soil and water conservation measures in Hekouzhen-Longmen section have changed significantly and forest measures has the greatest contribution to water and sediment reduction.c) With the increases of the basin scale,the sediment reduction benefits of water and soil conservation comprehensive measures tend to decrease.