草本植物对土质路面径流水动力学特征及水沙过程的影响

Influence of herbaceous plants on runoff hydraulic characteristics and sediment generation on terrene roads

通过室内人工模拟降雨,研究了草本植物不同覆盖度土质路面的径流水动力学特征以及路面的产流产沙过程。结果表明,路面径流的弗劳德数和雷诺数属层流的急流范畴,并且二者与径流流速及过水断面单位能量相同,均随草本植物覆盖度的增大而减小。而Darcy-weisbach阻力系数以及曼宁糙率系数则均随覆盖度的增大而增大。在不同覆盖度土质路面上,径流量随径流时间急剧增大后趋于稳定,且二者符合移轴双曲线关系,而输沙率则经历了先增大后减小的过程。随着植被覆盖度的增大,土质道路的水分入渗率逐渐增大,而径流量、输沙率及含沙率均逐渐减小。该研究表明土质路面种植的草本植物具有较好的水土保持功能,为阐明草本植物与土壤侵蚀的关系提供了理论依据。

Indoor rainfall simulation was employed to investigate the hydraulic characteristics of runoff, and runoff generation and sediment generation processes on terrene roads with different coverage degrees of herbaceous plants. The study indicated that on the roads the Froude numbers and Reynolds numbers of runoff fell into the category of supercritical flow of laminar flow. Their unit energies were consistent with the runoff velocity and water-carrying section, which were decreased with the increasing of the coverage degrees of herbaceous plants. The Manning roughness coefficients and the Darcy-weisbach friction coefficients increased as the coverage degrees increased. On the terrene roads with different coverage degrees, the amounts of runoff initially increased sharply and then stabilized with runoff-lasting time. Both the amounts of runoff and the runoff-lasting time were following an offset hyperbola, whereas the sediment yield rates initially increased and then declined. With the increasing of coverage degrees, the infiltration rates of water into the terrene roads gradually increased and the amounts of runoff, sediment yield rates and sediment concentration all gradually decreased. The study revealed that on terrene roads herbaceous plants could play a favorable role in soil and water conservation and provided a theoretical basis for understanding the relations between herbaceous plants and soil erosion.