细沟侵蚀可蚀性参数及土壤临界抗剪应力的有理(实验)求解方法

Rational Computational Method of Soil Erodibility and Critical Shear Stress from Experimental Data

利用室内细沟侵蚀模拟试验结果 ,把细沟可蚀性参数和土壤临界抗剪应力的研究与侵蚀的过程结合起来 ,通过对土壤水蚀预报模型WEEP中控制土壤侵蚀的水动力学模型进行理论分析 ,导出了由实验直接计算得到细沟侵蚀可蚀性参数Kr 值及土壤临界抗剪切应力τc的方法 .由推导得到的计算方法与计算公式 ,求得了不同工况下细沟侵蚀可蚀性参数及相应的临界抗剪切应力值 .结果表明 ,对于同一种土壤 ,在不同的水动力学条件下 ,计算得到的细沟侵蚀可蚀性参数基本是一致的 .对于实验所用的黄绵土 ,计算得到的细沟可蚀性参数Kr 均值为( 0 32 4± 0 0 0 3)kg·N-1·s-1.临界抗剪切应力τc 随坡度的增大有增大的趋势 .不同水动力条件下回归系数值均大于 0 71 .提出的计算细沟侵蚀可蚀性参数Kr 值及土壤临界抗剪切应力τc的方法 ,将有助于建立和完善土壤侵蚀预报过程模型 .

With the analysis of the Water Erosion Prediction Project(WEEP), simulated rill experiment in laboratory was conducted to determine the soil erodibility parameter K r and critical shear stress τ c. The result shows that soil erodibility parameter K r is the same for a same experimental soil with similar soil physical conditions under different slope gradients. Soil erodibility parameter K r of used silt-clay soil (Loess soil) is (0.324±0.003) kg·N -1 ·s -1 on the average. Critical shear stress τ c tends to increase with the slope gradient, for 3.198 N·m -2 ,3.976 N·m -2 ,4.043 N·m -2 ,4.165 N·m -2 ,4.870 N·m -2 under 5°,10°,15°,20°,25°respectively. The coefficients of determination R 2 are more than 71% under different hydraulic conditions. The paper advances a rational method to calculate quantitatively the soil erodibility parameter K r and critical shear stress τ c, which is helpful for developing and perfecting the soil erosion prediction model.