太行山区侧柏林地人工降雨下的入渗特性

Infiltration Characteristics under Simulated Rainfall over Platycladus Orientalis Land in Taihang Mountainous Region

对降雨入渗的研究是揭示华北地区水源地来水量变化研究的基础。运用人工模拟降雨,在2个2m2的径流小区(编号为P1、P2,坡度分别为19.6°,11.7°)上研究了太行山区侧柏林地的入渗特性,分析了雨强、土壤前期含水量和坡度对入渗的影响。结果表明:(1)入渗过程经历了供水控制阶段和剖面控制阶段,在供水控制阶段,降雨全部入渗,雨强越大,初始入渗率越大;在剖面控制阶段,表观入渗率逐渐降低并直至稳定,而P2小区的首场降雨中表观入渗率却呈现出"先降低后升高"的特点且供水控制阶段时间更短;(2)雨强越大,初始入渗率越大。在P1小区,表观稳定入渗率随雨强增大而增大,这一现象并没有在P2小区出现;(3)土壤前期含水量越大,供水控制阶段的时间越短;对比场次降雨下的土壤负压势变化表明湿润锋运动速度随土壤前期含水量的增加而增快;(4)坡度较大的P1小区(19.6°),其平均表观稳定入渗率较大(0.57mm/min),P2小区(11.7°)的平均表观稳定入渗率较小(0.35mm/min)。

The paper has applied simulated rainfall over two runoff plots to investigate the infiltration characteristics under Platycladus orientalis,which can provide a theoretical basis for the variation of mountain inflow flowed to the north China plain.The two runoff plots have a identical area of 2 m^2,numbered P1 and P2,which have slope gradients of 19.6°and 11.7°respectively.Results indicated that：（1） Infiltration rates experienced two stages：supply control stage and profile control stage.Infiltration rates declined and reached to a steady stage during the course of profile control stage.The infiltration process of the first rainfall event on P2 plot presented a course of ＂decrease-increase＂ ;（2） The initial infiltration rate increased with increasing rainfall intensity.On the P2 plot,apparent steady infiltration rate of each rainfall event was not a fixed value which was affected by rainfall intensity,while apparent steady infiltration rate decreased with rainfall events on P1 plot;（3） Antecedent soil moisture influenced the movement of wet front noticeably：the greater antecedent soil moisture,the faster wet front moved;（4） The influence of slope gradient on infiltration was that mean apparent infiltration rate was larger and the infiltration rate reached to steady state faster when slope gradient was larger.The research is a preliminary study of water transformation in Taihang mountainous region.