模拟降雨下枯落物调控坡面产流产沙过程及特征研究

本研究采用模拟降雨实验的方法,研究了30、60和90 mm/h降雨强度下,5种枯落物覆盖坡面径流的水动力学特征,以期揭示枯落物覆盖条件对坡面产流产沙过程及其径流水动力学特征影响。研究结果表明:坡面平均产流率和产沙率随降雨强度增大而增大,随枯落物生物量增加而减小,并且与降雨强度和枯落物生物量之间均为指数函数关系;坡面流量-历时曲线稳定流量值主要受降雨强度的影响;产沙率-历时曲线稳定产沙率受降雨强度和枯落物生物量等多种因素的影响;枯落物覆盖对坡面径流水动力学特性有显著影响,相比于裸坡覆盖有50、100、150、200 g/m~2枯落物坡面径流平均流速相比裸坡减少率分别在17.7%、26.8%、37.9%、53.7%;雷诺数减少率分别在11.2%、18.7%、26.3%、33.4%左右;弗劳德数减少率在21.3%、30.3%、42.9%、61.2%左右,Darcy-Weisbach阻力系数增大了0.5~5.6倍;产沙率与Darcy-Weisbach阻力系数呈对数关系,与剪切力和径流功率呈线性关系,枯落物能显著增大径流临界剪切力和功率;产沙率(Dr)和各水动力学因子间有良好的相关关系,相关程度顺序为:RewVPFrft。

Runoff and sediment yield process and characteristics research on litter slopes in simulated rainfall

Litter is a key factor for determining erosion rates, to provide quantitative information for hydrological soil processes in litter covered slopes, different rainfall intensities(30, 60, 90 mm/h)were conducted under different litter coverage(0,50,100,150,200,250 g/m²)with the method of artificial rainfall in laboratory. The results show that runoff and sediment yield rates increase with increasing rainfall intensity and decrease with increasing litter coverage, the correlation relationships are exponential function; relatively stable runoff in runoff-duration curve is mainly affected by rainfall intensity; relatively stable sediment in sediment-duration curve are affected by rainfall intensity,litter and other factors; litter has significant influence on runoff dynamic characteristics, compared with the bare land, runoff velocity of slopes covered with 50, 100, 150 and 200 g/m² litter decreased by 17.7%, 26.8%, 37.9% and 26.8%, respectively, decrement of Reynolds number are 11.2%, 18.7%, 26.3% and 18.7%, and decrement of Froude number are 21.3%, 30.3%, 42.9% and 30.3%, respectively. Darcy-Weisbach resistance coefficient increase by 0.5-5.6 times; there is a logarithmic relationship between Darcy-Weisbach resistance coefficient and sediment yield rate, a linear relationship between runoff shear stress, runoff power and sediment yield rate. The correlation coefficients between sediment yield rate and hydrodynamic parameters decrease in the following order:Re> w> V> P> Fr> f> t.