上方来水来沙对细沟水流水力学参数的影响

利用供沙土槽和细沟土槽双土槽径流小区系统 ,定量分析了粘黄土陡坡地在 5 0、90和 1 30mm h降雨强度下上方来水来沙对坡下方细沟水流水力学参数变化的影响。结果表明 ,上方来水的汇入和降雨强度的增大 ,可使细沟水流流态由层流转变为紊流。上方来水来沙使细沟水流的流速、雷诺数、弗罗得数明显增大 ,而阻力系数明显减少 ,从而导致细沟侵蚀产沙量增大。定量分析了细沟水流流速、雷诺数和阻力系数与上坡来水引起坡下方净细沟侵蚀产沙量的关系 ,建立了一定条件下净细沟侵蚀产沙量与流速相对增量、雷诺数相对增量和阻力系数相对减量的数学统计模型

Effects of Up-Slope Runoff and Sediment on Rill Hydraulic Parameters

A dual-box system,consisting of a feeder box,located at up-slope,and a test box,located at down-slope was used to quantify impacts of runoff and sediment from up-slope on rill hydraulic parameters under different rainfall intensities of 50,90 and 130 mm/h.The results showed that up-slope runoff discharging into rill channel at down-shope section or an increase of rainfall intensities resulted in that rill flow shifted from stratum flow into turbulent flow.Runoff and sediment from up-slope caused a great increase of rill flow velocity and Reynolds number,and an obvious decrease of rill flow Daycy-weisbach coefficient.For these reasons,up-slope runoff discharging into rill channel at down-slope section caused a great increase of sediment delivery by rill flow.Meanwhile,the relation between rill flow velocity,Reynolds number and Daycy-weisbach coefficient,and net rill erosion amount caused by up-slope runoff was analyzed,respectively.A statistical model among the net rill erosion amount caused by up-slope runoff and relative increment of rill flow velocity,Reynolds number,and relative decrement of Daycy-weisbach coefficient was established.