刚性植被覆盖与生长方向对坡面径流分离能力的影响

Impact of Rigid Vegetation Coverage and Growth Orientation on Slope Runoff Detachment Capacity

摘要:

为探讨刚性植被茎秆覆盖度及生长方向对坡面径流分离能力（RDC）的影响，通过不同坡度（5°～20°）、覆盖度（0～15.89%）及两种植被生长方向（垂直于坡面（BS）和垂直于水平面（BH））的组合进行模拟试验。结果表明，坡度显著影响RDC分布范围（p<0.05），且该影响在BH条件下更明显。BS条件下RDC均值为裸坡的2.05～2.51倍，BH条件下为1.53～2.03倍。径流分离能力相对变化率小于0仅在植被数量N=95时出现（-6.87%～-0.51%），而N=187和N=286时分别为17.95%～88.49%和66.44%～156.57%。剪切力和水流功率为影响RDC的关键水力参数，BS条件下剪切力（相关系数为0.89）和水流功率（相关系数为0.82）与RDC显著正相关，BH条件下流速对RDC（相关系数为0.64）影响较强，阻力系数（相关系数为-0.11）影响较弱。SPSS回归分析表明剪切力和水流功率为预测RDC的关键参数，模型精度较高（R2=0.98、纳什效率系数为0.98）。

Abstract:

Aiming to investigate the effects of rigid vegetation stem coverage and growth orientation on the runoff detachment capacity (RDC) of slopes, a series of simulated experiments were conducted under different combinations of slope gradients (5°~20°), coverage levels (0~15.89%), and two vegetation growth orientations (perpendicular to the slope surface (BS) and perpendicular to the horizontal plane (BH)). The results showed that slope gradient significantly influenced the distribution range of RDC (p<0.05), with this effect being more pronounced under the BH condition. Under the BS condition, the mean RDC was 2.05~2.51 times that of bare slopes, while under the BH condition, it was 1.53~2.03 times. A relative change rate of RDC less than 0 was observed only when the vegetation coverage was N=95 (ranging from -6.87% to -0.51%), whereas for N=187 and N=286, the relative change rates were 17.95%~88.49% and 66.44%~156.57%, respectively. Shear stress and stream power were identified as the key hydraulic parameters influencing RDC. Under the BS condition, shear stress (correlation coefficient: 0.89) and stream power (correlation coefficient: 0.82) were significantly positively correlated with RDC, while under the BH condition, flow velocity (correlation coefficient: 0.64) had strong influence, and the resistance coefficient (correlation coefficient: -0.11) had weak effect. SPSS regression analysis indicated that shear stress and stream power were the critical parameters for predicting RDC, with the model demonstrating high-accuracy (R2=0.98, Nash efficiency coefficient=0.98).