降雨条件下秸秆覆盖坡面流水动力过程研究

The Flow Velocity of Loess Slope with Straw Mulching under Rainfall Conditions

降雨条件下径流流速对坡面水文和侵蚀过程具有重要影响,是水文和侵蚀模型研究中的重要参数之一。本文采用电解质示踪法,在不同降雨强度、秸秆覆盖量和坡长条件下,测量坡面流平均流速,流速变化范围为0.016~0.108 m/s。试验结果表明,降雨强度和秸秆覆盖量对坡面流流速均有显著影响,流速随降雨强度的增加而增加,且随秸秆覆盖量的增加而减小。径流流速沿坡长呈增加趋势,但增加的速率不断减小,最终达到稳定流速,随着降雨强度和秸秆覆盖量的增加,覆盖坡面流流速达到稳定流速的距离逐渐减小。研究揭示了降雨条件下覆盖坡面流流速的变化规律,可为秸秆覆盖坡面土壤侵蚀机理及相关研究提供基础。

Flow velocity is of great significance to understanding the process of inter-rill erosion and hydrology on a hill slope under rainfall conditions,which is an important parameter for hydrology and soil erosion modeling.A solute centroid method is employed to measure the velocity distribution of sheet flow based on solute transport process,to understand the influence of straw mulching on flow velocity.The measurements are made at slope lengths of 3,5,6 and 7 m under rainfall intensities of 80,120 and 160 mm/h,straw mulching quantities of 2 and 8 t/hm^(2),and slope gradient of 10°.The measurements clearly indicate that flow velocity is significantly affected by rainfall intensity and straw mulching quantity.In this paper,the velocity of sheet flow ranges from 0.016 to 0.108 m/s,increases with rainfall intensity,and decreases with straw mulching quantity.Flow velocity increases with the slope length,while the increase rate slows down before approaching a steady velocity.The distance for sheet flow velocity to reach its maximum becomes shorter under greater rainfall intensity and straw mulching quantity.This paper helps understand the hillslope hydrodynamics along the mulched slope under rainfall conditions.