中文摘要：

土壤侵蚀过程受控于侵蚀外营力和土壤抗侵蚀性能,深入理解坡面流水动力学特性及其侵蚀动力是研究土壤侵蚀动力学机制的基础。利用可变坡土槽,通过不同雨强（60、90和120 mm/h）和径流冲刷（10、15和20 L/min）组合模拟试验,研究了第四纪黏土红壤坡面水流的水动力学特征参数及其与土壤侵蚀量间的关系。结果显示：降雨和径流冲刷影响了坡面产流产沙过程和坡面流水力学特性,其中平均流速v、平均水深h、雷诺数Re和水流功率ω均随降雨强度和上方来水流量的增加而增大,相对水深曼宁糙率n/h则减小,其水力学他参数（弗如德数Fr、阻力系数f和水流剪切力τ）变化规律不明显。坡面水流平均速度取值范围为0.21-0.45 m/s,平均水深取值范围为5.6-9.4 mm,在试验条件下红壤坡面侵蚀水流流态大部分均处于＂紊流-急流区＂。不论从径流角度看或是从泥沙角度分析,由相对水深和曼宁糙率系数两种水动力因子共同组成的复合水动力特征参数-相对水深曼宁糙率,是表征不同上方来水流量和降雨强度条件下第四纪粘土红壤坡面侵蚀特征的水动力参数。

英文摘要：

The processes of soil erosion may be determined by two aspects： the erosive agents and resistance to erosion, and it is necessary to study flow hydraulics to understand mechanisms of water erosion and to predict soil loss. A series of experiments were conducted to assess the difference of flow hydraulics under the coexisting conditions of rainfall and inflow and to understand the relationship between flow hydraulics and soil erosion amount. A soil pan（3.0 m long, 0.5 m wide and 0.35 m depth and with an adjustable slope gradient of 0o-30o） was subjected to designed rainfall intensity（60mm·h-1, 90 mm·h-1 and 120 mm·h-1） and inflow rates（10 L·min-1, 15 L·min-1 and 20 L·min-1）. Our results suggested that both rainfall intensity and inflow rate played important roles in runoff formation, soil erosion and hydraulic characteristics.The average flow velocity（V）, the mean flow depth（h） and Reynolds number（Re） and the stream power（w） increased with rainfall intensity and inflow rate, and the rate of Manning roughness coefficient to mean flow depth（n/h） showed opposite trends. There were no obvious trend for the other flow hydraulics. The average flow velocity ranged from 0.21 m·s-1 to0.45 m·s-1 and the mean flow depth from 5.6 mm to 9.4 mm. Overland flow regimes existing in the slope were almost considered as turbulent and supercritical. The results indicated that the parameter of Manning roughness coefficient to mean flow depth was probably a better hydraulic parameter to predict sediment load and runoff rate in hillslope erosion processes of red soil under the coexisting conditions of rainfall and runoff.