应用文献［１］关于不同地貌类型及不同水保措施条件下黄河干支流中泥沙粒径分布的研究结果,可以对相应条件下的减沙效益进行有效的分析。利用文献［１］模型,本文不仅探讨了在给定地貌类型条件下各类水保措施实施前后流域汇入黄河干支流的泥沙总量的变化,而且还在扣除降雨变化的影响之后,预测了各类组合条件下非均匀泥沙中减沙效果最佳的粒径级和相应粒径级泥沙的减沙量,预测结果得到了黄河干支流各站所有实测资料的验证。文中还简要讨论了人类活动（主要是开矿）对减沙效益的影响。

Following the companion paper on the laws of sediment size distribution which account for the effects of the measures of water and soil conservation as well as the geomorphologic factors, this paper further deals with the sediment reduction effect of conservation measures in different catchments. Not only is the total reduction load inflowing into rivers (including tributaries and the main stream) due to the measures of water and soil conservation discussed,but also the grading portions of reduced sediment load are predicted and verified by the measured data. The grain size corresponding to the maximum reduction of sediment yield in the non uniform suspended sediment particles is accurately predicted by the model, which is of great importance in the benefit analysis of the measures of water and soil conservation in various catchments.