坡面径流调控薄层水流水力学特性试验

为澄清复杂地表的水流运动过程、水流水力学参数受流量及地表状况的影响，该研究采用野外标准径流小区实地放水冲刷试验，研究了鱼鳞坑、苜蓿草地、秸秆覆盖不同径流调控措施的坡面薄层水流水动力学特性的变化规律，包括水流流速、水深、流态、阻力系数。研究结果表明：坡面薄层水流的平均流速与水深主要受流量控制，其二者之间呈现幂函数关系；地表状况与流量大小直接影响着坡面流态，对于裸地与鱼鳞坑坡面，流量较小时属于层流与缓流，在流量达到3.0 m3/h时，属于过渡流、紊流和急流；而苜蓿草地、秸秆覆盖坡面均属于层流和缓流；并提出复杂坡面的阻力系数由颗粒阻力、形态阻力、波阻力叠加而成，其大小主要受地表状况影响；阻力系数与土壤侵蚀率呈现良好对数关系。总之，坡面采取径流调控措施后，其地表抗侵蚀力和泥沙搬运的能力明显强于裸地，径流流速明显降低，水流流态明显平缓，水流受阻力显著增加。研究结果对于揭示不同径流调控措施对坡面拦泥蓄水、减流减沙及侵蚀动力学机制有着重要的理论基础和实践指导意义。

Hydraulic characteristics of sheet flow with slope runoff regulation

In order to clarify the process of runoff movement under the complex surface conditions and the effect of flow and surface conditions on hydraulics parameters, the authors studied the hydraulic properties of shallow flow with different runoff by use of the field scouring experiments in the standard plots in this study. Thereinto, regulating measurers included the treatments of fish-scale pit, alfalfa grass, straw mulch and control, and hydraulic properties included flow velocity, flow depth, flow regimes and the resistance coefficient. The results indicated that the mean flow velocity and depth were mainly controlled by the slope runoff discharge, and there was also a power function relationship among mean velocity, depth and discharge. The slope flow regime was directly influenced by surface conditions and flow discharge. For the naked slope plot (control) and fish-scale pit plot, flow regimes were laminar flow and subcritical flow under the lesser discharge, and transitional flow under the discharge of 3.0 m3/h. For alfalfa grass plot and straw mulch plot, flow regimes were laminar flow and subcritical flow. The resistance coefficient on complex slope consists of granule resistance, configuration resistance and wave resistance and it was mainly influenced by the surface conditions. In a word, the capability of resisting soil erosion and sediment movement was stronger than the control whatever on grass and straw mulch slope or on the slope with fish-scale pits. At the same time, the measured slope had a function of slower runoff velocity and higher flow resistance.