中文摘要：

通过对野外凸型复合坡面进行3种流量（14L/min,18L/min,22L/min）、3种植被覆盖度（剪草裸坡,30%,70%）和2种坡长组合（上坡长5m,下坡长3m;上坡长8m,下坡长5m）的冲刷试验,对坡长和植被对黄土凸型复合坡面的产流产沙特性进行了深入研究。结果表明,（1）剪草裸坡时,在流量为14L/min时,产流量随坡长的增大而减小,产沙量随坡长的增大而增大;在流量为18L/min和22L/min时,产流产沙量均随坡长的增大而增大。当植被覆盖度为30%时,在各流量下,产流产沙量均随坡长的增大而增大;当植被覆盖度为70%时,在流量为14L/min和18L/min时,产流产沙量随坡长的增大而增大,在流量为22L/min时,产流量随坡长的增大反而减小,产沙量随坡长的增大仍呈增大趋势。（2）剪草裸坡时,在流量为14L/min时,复合坡面的产流速率随坡长的增大呈递减趋势,产沙速率随坡长的增大却呈递增的趋势,在流量为18L/min和22L/min时,复合坡面的产流产沙速率均随坡长的增大而增大。当植被覆盖度为30%和70%时,在各冲刷流量下,复合坡面的产流产沙速率均随坡长的增大而增大。（3）不同植被覆盖度、不同冲刷流量和不同坡长组合的复合坡面,累积产沙量和累积产流量间呈递增的函数关系,但函数表达式不统一,即复合坡面的累积产沙量与累积产流量之间的关系不仅与坡长、植被覆盖有关,而且还与冲刷流量有关。

英文摘要：

The effect of slope length and vegetation cover on runoff and sediment yield process in the loess convex composite slopes was studied by scouring experiments with 3vegetation coverage degrees（bare slope with mowing,30% and 70%）,3water inflow rates（14L/min,18L/min and 22L/min）,2slope length combinations（5muphill＋3mdownhill,and 8 muphill＋5 mdownhill）.The results showed that：（1）In bare slope with mowing,when the flow rate was 14L/min,runoff yield decreased,while sediment yield increased,with the increase of slope length.When the flow rates were 18L/min and 22L/min,the runoff and sediment yield all increased with the increase of slope length.When the vegetation coverage was 30%,runoff and sediment yield increased with the increase of slope length under all inflow rates.When the vegetation coverage was 70% and flow rates were 14 L/min and 18 L/min,runoff and sediment yield increased with the increase of slope length.When the inflow rate was 22L/min,runoff yield decreased,while sediment yield increased,with the increase of slope length.（2）In bare slope with mowing,when inflow rate was 14L/min,the runoff yield rate decreased,while sediment yield rate increased,with the increase of slope length.When the flow rates were 18L/min and 22L/min,runoff and sediment yield rate increased with the increase of slope length.When the vegetation coverages were 30% and 70%,under all inflow rates,runoff and sediment yield rate all increased with the increase of slope length.（3）In composite slopes with different vegetation cover,different inflow rate and different combinations of slope length,cumulative runoff and sediment yield showed an increasing function relation.But the function expressions were not uniform under different inflow rates,which indicated that the relationship between cumulative runoff and sediment yield not only related to the slope length and vegetation cover,but also related to the inflow rate.