上方来水来沙对浅沟侵蚀产沙及水动力参数的影响

Effects of up-slope runoff and sediment on ephemeral gully erosion sediment and hydraulic parameters

浅沟侵蚀是黄土高原重要的侵蚀类型,上方汇水对坡面浅沟侵蚀具有重要的影响。采用野外放水冲刷试验,定量分析26°坡耕地在上方来水量为5、10和15 L/m in时对坡下方浅沟侵蚀产沙及其水动力参数的影响。结果表明:上方来水的汇入使浅沟水流流速明显增大,雷诺数、弗劳德数、水流功率和剪切力分别增大33%～76%、21%～47%、29%～72%和18%～42%,阻力系数减少11%～13%,导致浅沟侵蚀产沙量明显增大;除流速和弗劳德数外,其余水动力参数随放水时间的延长呈递增趋势;上方来水使浅沟侵蚀产沙量相对增量与水流功率和剪切力相对增量均呈幂函数关系。

The ephemeral gully erosion was an important issue and had great distribution in the Loess Plateau.The runoff and sediment from up-slope had great impacts on slope soil erosion.In this paper,its effect on down-slope ephemeral gully erosion sediment yield and hydrodynamic parameters were analyzed by water discharge scouring experiments in fields,with the designed discharge 5 L/min,10 L/min and 15 L/min on the slope of 26°.The results indicated that the runoff from up-slope increased the flow velocity.The Reynolds number,Froude number,stream power and shearing force increased by 33%-76%,21%-47%,29%-72%,18%-42% respectively,and the Daycy-Weisbach coefficient decreased by 11%-13%,which caused the increasing sediment of the ephemeral gully erosion.Except the flow velocity and Froude number,the other hydrodynamic parameters increased over the water discharge scouring time.There was a power relationship between ephemeral gully relative increment sediment yield caused by up-slope runoff and relative increment of the stream power and shearing force.