中文摘要：

径流冲刷和分离土壤是土壤坡面侵蚀产沙的必要途径和重要过程，准确预测径流分离土壤过程对完善土壤侵蚀物理模型具有重要意义。利用变坡钢槽，在不同坡度（8．8％～46．6％）和流量（0．5～2．5Ls-1）组合下，研究了西南地区坡面土壤分离速率与坡度、流量以及水流剪切力、水流功率、单位水流功率的关系，对比了相同流量典型坡度组合下黄壤与黄土的分离速率差异。研究结果表明，西南地区黄壤坡面径流分离速率随坡度和流量的增大而增大；坡度和流量的多元回归分析结果能够很好地预测径流分离土壤的速率值（R2=0．9）。水流功率和单位水流功率与径流分离速率呈现较好的幂函数关系，决定系数比较接近（R2=0．83、0．79）；而水流剪切力预测黄壤分离速率较差（R2=0．18）。黄土坡面径流分离土壤的速率明显大于黄壤坡面，且二者分离速率差异随坡面冲刷流量的增大而增大。尽管坡度、流量、水流功率和单位水流功率均可以很好地预测径流分离土壤的速率，且回归方程形式与国内他人研究相差不大，但方程中表征土壤可蚀性的系数相差较大，体现了黄壤坡面侵蚀过程及其受径流影响作用的特殊性。

英文摘要：

Soil detachment is an unavoidable path and important process of slope soil erosion and sediment yield. Precise prediction of the process of soil detachment is of great significance to the consummation of a physical model for soil erosion. A runoff scouring experiment, designed to have a hydraulic flume, of which the slope gradient is adjustable with the range of 8.8% -46.6% , and various flows （0.5 -2.5 L s-1 ） was carried out to study relationships of soil detach- ment rate with slope, flow, shear stress, stream power and unit stream power on yellow soil slopes in Southwest regions, and difference between yellow soil and loess in soil detachment rate in the case of the same flow rate and typical slope of the regions. Results show that the soil detachment rate of yellow soil in the Southwest region increases with the flow and slope. Multiple regression analysis of the slopes and flows may be used to predict detachment rate of the soil very well （ R2 = 0.9）. Stream power and unit stream power both display good power function relationships with soil detachment rate of the yellow soil, with determination eoefficient（R2） being 0.83 and 0.79, respectively. However, flow shear stress is not a good factor to predict soil detachment rate （R2 = 0. 18）. In Loess, the soil detachment rate is obviously higher than in yellow soil, and the difference between the two soils in soil detachment rate widens with increasing slope scouring flow. Although flow, slope, stream power and unit stream power all can be used to predict soil detachment rate, and their regression equation differ slightly from those in other domestic researches, the coefficients that characterize soil erodibility in the equations differ sharply, which reflects the particularity of the soil erosion process of yellow soil being affected by runoff.