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采用绝对/相对保水减沙比指标来反映降雨径流的调控利用效果,绝对保水减沙比指标反映流域经过调控后所保有的降水资源量与侵蚀产沙量的比值;相对保水减沙比指标反映流域经过调控后拦截单位泥沙所减少的地表径流量。选取黄土高原多沙粗沙区7个主要支流,以1960-2009年为研究时段,对其保水减沙效应进行了评价。结果表明:1960-1999年间各流域内绝对/相对保水减沙比指标波动变化幅度较大,但在2000-2009年间,各个支流绝对/相对保水减沙比指标分别急剧增加和下降,表明国家退耕还林(草)工程实施成效显著。保水减沙比指标不仅可作为评价流域降雨径流调控利用效果的有效指标,而且还可作为流域水土保持与生态建设效果评价的一个综合性指标。
The absolute / relative index of water and sediment reduction reflects the effect of regulation and utilization of rainfall and runoff. The absolute index of water and sediment transport reflects the ratio of the amount of precipitation and the amount of erosion and sediment retained by the basin after regulation and control. The index of relative water and sediment transport reflects After regulation, the river basin intercepts the sediment reduction of surface runoff. Seven major tributaries of the sandy loess plateau in the Loess Plateau were selected, and the effects of water and sediment reduction were evaluated from 1960 to 2009 as the study period. The results show that the index of absolute / relative water and sediment transport in the watershed varies greatly between 1960 and 1999, but the index of absolute / relative water and sediment transport (SST) of each branch sharply increases and decreases from 2000 to 2009, respectively. Forest (grass) project implementation achieved remarkable results. Water and sediment index can not only be used as an effective index to evaluate the effects of rainfall and runoff regulation but also serve as a comprehensive index to evaluate the effect of soil and water conservation and ecological construction in the basin.