红壤丘陵区3种典型坡面排水沟的排水输沙特征

Characteristics of drainage and sediment transport for three typical ditches in red earth hilly area

以红壤丘陵区坡面排水沟为研究对象,通过对野外水泥沟、土沟、草沟3种不同下垫面坡面排水沟的挟沙水流放水试验,研究不同排水沟的排水输沙特征。结果表明:不同排水沟的产流开始时间、产流滞后时间从大到小依次为草沟、土沟、水泥沟,并且不同排水沟间有显著性差异;随着放水流量增大,排水沟产流开始时间均减小,但是产流滞后时间无显著变化;不同排水沟径流流速从大到小依次为水泥沟、土沟、草沟,水泥沟、土沟随着距沟顶距离增大径流流速先增大后趋于稳定,草沟随着距沟顶距离增大径流流速减小;从6L/min到12L/min流量放水,水泥沟、土沟、草沟平均径流流速增幅分别为14%、32%、40%;不同排水沟间排水量有显著性差异,排水速率从大到小依次为水泥沟、土沟、草沟,随着放水流量的增大,排水速率增大,排水流量过程均为先增大后趋于稳定;不同排水沟输沙量具有显著性差异,输沙量从大到小依次为水泥沟、土沟、草沟,随着放水流量增大,输沙量增大。红壤丘陵区坡面不同类型排水沟的排水输沙特征差异显著。

A field scouring experiment was conducted in red soil hilly region to study the characteristics of drainage and sediment transport of cement ditch, earth ditch and grass ditch. The results suggested the start time and cut-off time of runoff for different ditches were significantly different （P〈 0. 05）. The start time and cut-off time of runoff for three ditches decreased in an order of cement ditch, earth ditch and grass ditch. With the increase of the scour flow, the start time decreased, but the cut-off time showed no significant variation trend. Secondly, the descend order of the drainage velocity in different ditches was cement ditch, soil ditch and grass ditch. The drainage flow velocity of the cement ditch and the earth ditch increased at first and then tended to be stable with the increase of the distance from the slope section, but drainage velocity in grass ditch decreased. With the increase of scour flow from 6 L/min to 12 L/min, the average drainage velocity in cement ditch, soil ditch and grass ditch increased by 14%, 32% and 40%, respectively. Drainage per unit time in the cement ditch was highest, followed by the earth ditch, and the grass ditch was lowest. With the increasing of scour flow, total runoff increased. The runoff process firstly increased and then tended to be stable in all of ditches. Lastly, there are significant differences in sediment yields among different ditches. The sediment load decreased in an order of cement ditch, earth ditch and grass ditch. As scour flow increased, the sediment yields in all ditches increased. The drainage and sediment load of different ditches were significantly different in the red soil hilly region