细沟侵蚀过程与细沟水流水力学参数的关系研究

利用供沙土槽和试验土槽的双土槽径流小区 ,定量研究了在不同降雨强度下上方来水来沙对陡坡地细沟侵蚀产沙过程和细沟水流水力学参数的影响及其细沟水流水力学特征参数与细沟侵蚀产沙量的关系。结果表明 :坡面细沟侵蚀过程以侵蚀—搬运过程为主 ,坡上方来沙不仅被径流全部搬运 ,且上方来水在坡下方引起了另外的侵蚀产沙量 ,其值随上方来水含沙量的减少和降雨强度的增加而增大。上方来水的汇入或降雨强度的增大可使细沟水流流态由层流转化为紊流。上方来水对细沟水流水力学参数 (流速、水力半径、雷诺数、弗劳德数和阻力系数 )有重要影响。定量分析了细沟水流水力学特征参数 (流速、雷诺数和阻力系数 )与上坡来水引起坡下方净侵蚀产沙量的关系 ,建立了净侵蚀产沙量与细沟水流流速、雷诺数和阻力系数统计模型。

Research on Rill Erosion Process and Rill Flow Hydraulics Parameters

A dual box system, consisting of a 2 m long feeder box and a 5 m long test box with 150 gradient was used to quantify effects of run on water and sediment on rill erosion process at down slope section and rill flow hydraulics parameters, as well as relationship of rill flow hydraulics parameters and sediment delivery by rill erosion. The results showed that detachment transport was dominated in rill erosion processes, runoff from up slope always caused additional sediment delivery in the rill box, the additional sediment delivery increased with a decrease of sediment concentration in runoff from the feeder box and an increase of rainfall intensity. Up slope runoff discharging into rill channel at down slope section or an increase of rainfall intensity resulted in that rill flow shifted from stratum flow into turbulent flow. Runoff from up slope had an important effect on rill flow hydraulics parameters, such as rill flow velocity, Reynolds number and Daycy weisbach coefficient. The relation between rill flow hydraulics parameters and additional sediment in rill channel caused by up slope runoff was analyzed. And a statistic model among the additional sediment in rill channel and relative increment of rill flow velocity and Reynolds number, as well as relative decrement of rill flow Daycy weisbach coefficient was established.