中文摘要：

降雨产流阈值是受雨下垫面能够产流的最小降雨量值，是产流产沙规律研究的重要参数。采用室外人工模拟降雨试验，用传统直线回归法推求了4种下垫面条件下坡面降雨产流阈值，并综合考虑了其他因素对降雨产流阈值的影响，建立了一种多参数非线性降雨产流阈值模型。结果表明：传统直线回归法得到的4种不同调控措施下坡面的降雨产流阈值分别为：裸坡9．4mm、黑麦草23．6mm、苜蓿15．8mm和春小麦19．5mm。结合直线回归法并充分考虑降雨强度、植被覆盖度和前期土壤含水量3个因素对降雨产流阈值的影响，通过多元回归分析建立了一种多参数非线性降雨产流阈值模型，由该模型得到的4种不同调控措施下坡面的降雨产流阈值分别为：裸坡13．4mm、黑麦草23．7mm、苜蓿18．8mm和春小麦19．7mm。用实测数据对模型进行检验，计算值与实测值吻合程度较高，证实了该多参数非线性模型的适合性与可行性。

英文摘要：

Rainfall-runoff threshold is the minimum rainfall producing surface runoff and it is an important parameter for the research of runoff and sediment yield law. In this paper, the field artificial rainfall simulation experiments were carried out, and the rainfall threshold for different vegetation covers was obtained using the traditional regression method. Moreover, a nonlinear multi-parameter rainfall-runoff threshold model was established to analyze the effects of other factors on rainfall-runoff threshold. The results indicated that the rainfall-runoff thresholds of four different control measurements （bare slope, ryegrass slope, purple medic slope, and spring wheat slope） determined by the traditional linear regression method were 9.4, 23.6, 15.8 and 19.5 mm, respectively. Considering the effects of rainfall intensity, vegetation coverage and antecedent soil water content on the rainfall-runoff threshold, a nonlinear multi-parameter rainfall-runoff threshold model was established by using multiple regression analysis. By this model, the rainfall-runoff thresholds of the four different control measurements mentioned above （bare slope,ryegrass slope,purple medic slope, and spring wheat slope） were obtained as 13.4, 23.7, 18.8 and 19.7 mm, respectively. The nonlinear multi-parameter rainfall-runoff threshold model was tested by measured slope runoff data, and the results show that the calculated and measured thresholds match well, which proves that it is feasible to apply the nonlinear multi-parameter rainfallrunoff threshold model to ascertain the rainfall-runoff threshold.