裸露岩石对喀斯特坡地水土流失及水动力特征的影响

Effects of Exposed Rock on Soil and Water Loss and Hydrodynamic Characteristics of Karst Slope Land

[目的]裸露岩石如何影响坡地产流产沙及水动力特征尚需进一步深入研究。[方法]通过室内模拟试验,设置不同岩石裸露率(0,10%,30%,50%,70%)的坡地,开展不同雨强(30,60,90 mm/h)条件下的人工模拟降雨试验,旨在探究雨强与裸露岩石对坡地产流产沙及水动力特征的影响。[结果]坡地地表产流产沙随雨强增大呈增大趋势,而随岩石裸露率的增加呈减小趋势。在不同雨强条件下,0岩石裸露率坡地与10%岩石裸露率坡地的产流产沙差异多呈不显著(p>0.05),而与其他岩石裸露率坡地之间呈显著差异(p<0.05)。低岩石裸露率坡地(10%)与高岩石裸露率坡地(50%及以上)间产流产沙差异显著(p<0.05)。流速(V)、水深(h)、雷诺数(Re)、弗罗德数(Fr)、水流剪切力(τ)及水流功率(w)随雨强增大呈增大趋势,阻力系数(f)随雨强增大呈减小趋势。流速(V)、弗罗德数(Fr)随着岩石裸露率增加呈减小趋势,而水深(h)、阻力系数(f)随着岩石裸露率增加呈增大趋势,雷诺数(Re)、水流剪切力(τ)与水流功率(w)在不同雨强下变化规律有差异。水动力参数变化在不同坡地间具有一定差异性。产沙与水动力参数数量关系以指数函数拟合效果最好,流速(V)(R^(2)=0.819,p<0.05)、水流剪切力(τ)(R^(2)=0.858,p<0.05)及水流功率(w)(R^(2)=0.890,p<0.05)预测坡地产沙效果较好,其中水流功率(w)为最佳预测参数。[结论]研究结果进一步丰富了岩溶坡地土壤侵蚀理论,并可为建立适合于岩石裸露坡地的水蚀预测模型提供参考。

[Objective]The effects of exposed rocks on the runoff,sediment yield,and hydrodynamic characteristics of slope land needs further study.[Methods]Through the laboratory simulation test,the slope lands with different rock exposure rates(0,10%,30%,50%,70%)were set,and the artificial simulation rainfall test under different rainfall intensities(30,60,90 mm/h)was carried out,in order to explore the impact of rainfall intensity and exposed rocks on runoff,sediment yield and hydrodynamic characteristics of slope land.[Results]The surface runoff and sediment yield of slope land increased with the increased of rainfall intensity,and decreased with the increase of rock exposure rate.Under varying rainfall intensities,the runoff and sediment yield of slopes with 0 and 10%rock exposure rates slope land were not significantly difference in most cases(p>0.05),but the slope with a 0 rock exposure rate was significantly difference from other slopes with rock exposure(p<0.05).There was a significant difference in runoff and sediment yield between lands with low rock exposure rates(10%)and lands with high rock exposure rate(50%or more)(p<0.05).Flow velocity(V),Flow depth(h),Reynolds number(Re),Froude number(Fr),Water flow shear stress(τ)and Flow power(w)increased with the increased of rainfall intensity,the Friction coefficient(f)decreased with the increase of rainfall intensity.The Flow velocity(V),and Froude number(Fr)decreased with the increased of rock exposure rate,while the Flow depth(h)and Friction coefficient(f)increased with the increase of rock exposure rate,and the change regulation of Reynolds number(Re),Water flow shear stress(τ)and Flow power(w)were disparate in different rainfall intensity.Moreover,there were certain differences in hydrodynamic parameters among different slope lands.The quantitative relationship between sediment yield and hydrodynamic parameters was best fitted by Exponential function,Flow velocity(V),(R^(2)=0.819,p<0.05),Water flow shear stress(τ)(R^(2)=0.858,p<0.05)and Flow power(w)(R^(2)=0.890,p<0.05)had better prediction effects on sediment yield of slope land,and Flow power(w)was the best prediction parameter.[Conclusion]The development of this study has further enriched the theory of soil erosion in karst areas,and can provide reference for the establishment of water erosion prediction model suitable for exposed rock slope land.