积水动边界条件下滴灌土壤水分入渗研究(Ⅰ)——室内试验

Numerical simulation on water infiltration law of drip-irrigated soil under dynamic boundary condition of surface ponding(Ⅰ):Lab-experiment

为更好地指导滴灌工程实践,针对滴灌土壤表面积水的现象,系统研究了滴灌积水动边界条件下土壤水分入渗规律。通过室内试验,专门对积水条件下不同滴灌流量的滴灌湿润体、土壤水分入渗湿润锋和地表积水范围进行了试验分析,结果表明:积水动边界条件下,滴灌湿润体在灌水后很长一段时间内表现为一平卧的半椭球体。无论是水平湿润锋、垂直湿润锋以及湿润比,还是地表积水范围,都与入渗时间符合较好的幂函数关系。另外,无论滴头流量大小,湿润比随着灌水历时的增加都逐渐变小,但均大于1。滴头流量对地表积水范围的影响很大,地表积水稳定范围及其达到稳定的时间都随滴头流量的增加而增大。同时,地表积水稳定范围与滴头流量也能符合较好的幂函数关系。

To better guide the engineering practice of drip irrigation, the soil water infiltration law under the dynamic boundary condition of surface ponding induced by drip irrigation is systematically studied herein for the phenomenon of the surface pon- ding. Through the lab-experiment concerned, the wetted body of soil, wetting front of soil water infiltration and surface ponding area of the drip irrigation with various flow rates under the condition of surface ponding are tested and analyzed. The result shows that the drip irrigation wetting body looks like the pattern of a horizontal semi-ellipsoid within a long period after irrigation under the dynamic boundary condition of surface ponding. Furthermore, whether the horizontal wetting front, vertical wetting front and wetting ratio or the surface ponding area are all better coincided with the power function relationship with the infiltration time. Moreover, whether the emitter flow-rate is large or small, the wetting ratio is all along to be gradually decreased with the in- crease of the irrigation duration, but all are to be larger than 1. The emitter flow-rate has a great impact on the area of the surface ponding, and then both the surface ponding area and the time when it is stabilized are increased with the increment of the emitter flow-rate. Simultaneously, the stabilized area of the surface ponding and the emitter flow-rate can be better coincided with the power function relationship as well.