中文摘要：

坡面细沟侵蚀速率和水动力学参数在坡面细沟发育过程中存在明显的时空变化。基于间歇性人工模拟降雨和三维激光扫描技术提取的高精度DEM,分析了黄土坡面细沟发育不同主导过程中细沟侵蚀和水动力学参数的时空分布规律。结果表明,细沟侵蚀速率和总侵蚀速率的最大值出现在以细沟沟底下切侵蚀为主的细沟发育活跃期,最小值出现在以沟头溯源侵蚀为主的细沟发育初期。细沟侵蚀速率与总侵蚀速率随降雨历时的变化皆呈先上升后趋于稳定,并在一定范围内波动的变化趋势,且总侵蚀速率早于细沟侵蚀速率达到稳定。细沟侵蚀量随单位斜坡长呈先上升后下降的抛物线形式分布,细沟侵蚀速率的最大值出现在坡面中下部。90 mm/h降雨强度下径流剪切力、径流功率和单位径流功率分别是60 mm/h降雨强度下的1.3、1.1、1.4倍。细沟间水流和细沟流的水动力学参数随降雨历时的增加呈不同的变化趋势。两种降雨强度下,径流剪切力、径流功率和单位径流功率随单位坡长的分布均呈波动上升趋势。单宽细沟侵蚀量与水动力学参数之间呈线性正相关关系,细沟发育初期坡面侵蚀发生的临界径流剪切力、临界径流功率和临界单位径流功率最大。

英文摘要：

Rill erosion rate and hydrodynamic parameters present evident spatial and temporal variation characteristics during rill development process on hillslopes. Based on 3D laser scanning technique（ LiDAR） and intermittent simulated rainfall experiments,high-precision DEMs were extracted. Temporal and spatial variations of rill erosion and hydrodynamic parameters at different rill development stages on loessial hillslope were analyzed. Results showed that the maximum values of rill erosion rate and hillslope erosion rate occurred at the rill deep cutting dominated stage,while the minimum values of them occurred at the rill headcut dominated stage. Rill erosion rates and hillslope erosion rates were increased at first and then tended to be steady and fluctuated in a certain range with rainfall duration. Hillslope erosion rates reached steady state earlier than rill erosion rates. Rill erosion rates and hillslope erosion rates under90 mm / h rainfall intensity reached steady states earlier than those under 60 mm / h rainfall intensity. Rill erosion rates were first increased and then decreased along hillslope and showed parabola trend. Themaximum values of rill erosion rate occurred at the hillslope lengths of 6 m and 7 m. Shear stress,stream power and unit stream power under 90 mm / h rainfall intensity were 1. 3,1. 1 and 1. 4 times as those under 60 mm / h rainfall intensity. Hydrodynamic parameters of overland flow and rill flow showed different variation trends with the increase of rainfall duration. Shear stress,stream power and unit stream power were increased with fluctuations of unit slope length under two rainfall intensities. It showed strong positive linear correlation between rill erosion per unit width and three hydrodynamic parameters. The critical values of shear stress,stream power and unit stream power reached the maximum values at initial phase of rill development.