砒砂岩坡面侵蚀产沙规律及多元回归估算模型研究

Study on the Pattern of Erosion and Sediment Yield and Multiple Regression Estimation Model of Pisha Sandstone Slope

[目的]揭示砒砂岩坡面侵蚀产沙规律并初步建立侵蚀产沙估测模型,为创新砒砂岩区水土流失综合治理新措施提供参考。[方法]利用室内人工模拟降雨试验,依据18个工况的试验数据,定量研究了不同降雨强度、植被覆盖度和坡度3个因素对砒砂岩坡面降雨侵蚀产沙量的影响规律,并通过多元非线性回归方程建立了坡面侵蚀产沙预测模型。[结果](1)砒砂岩坡面产沙规律曲线均属于平缓型,每分钟产沙量随降雨历时呈现逐渐增大并直至稳定。(2)坡面产沙量受降雨强度的影响最为强烈,植被其次,坡度最小,且降雨强度对植被的减沙效益具有一定的影响,随着降雨强度的增加,低覆盖度的植被减沙效益降低。(3)产沙量同降雨强度呈幂函数关系,而同坡度和植被覆盖度在一定范围内呈线性关系。[结论]通过多元非线性回归方程所建立的侵蚀产沙估算方程的拟合相关系数(R^(2))可达到0.980,可以有效反映坡面侵蚀产沙量与各个影响因素的相互关系,具有较高的适用性。

[Objective]The aims of this study are to explore the pattern of erosion on Pisha sandstone slope and establish the estimation model,and to provide reference for innovating the new measures of soil erosion control in Pisha sandstone area.[Methods]The effects of rainfall intensity(20,50 and 80 mm/h),vegetation coverage(10%,30%and 50%)and slope(20°,30°and 40°)on sediment yield pattern were examined,and an estimation model of erosion and sediment yield on slope was established through multiple nonlinear regression equation.[Results]The sediment yield curve of the Pisha sandstone slope appeared a gentle growth,and the sediment yield in per minute increased gradually with the duration of rainfall and then became stable.Among the factors,the sediment yield was most strongly affected by rainfall intensity,followed by vegetation,and the smallest effect factor is slope.Additionally,the sediment reduction efficiency of vegetation was also affected by rainfall intensity.As rainfall intensity increased,the sediment reduction efficiency of vegetation with low coverage decreased.The sediment yield had a power function relationship with rainfall intensity,while it had a linear relationship with slope gradient and vegetation coverage within a certain range.A multivariate nonlinear regression model for erosion and sediment yield of Pisha sandstone slope was established.[Conclusion]The fitting correlation coefficient R^(2) of the established erosion and sediment yield estimation equation reaches 0.980 under the specific conditions of the standard plot,which can effectively reflect the relationship between slope erosion and sediment yield and various influencing factors,and the estimation model has high applicability.