降雨集流渗灌系统室内模拟土壤水分运动研究

为解决宁南山区旱地经济林干旱缺水的现状及小降雨(4~16 mm)无法入渗到根系(20~40 cm)分布范围,设计了一种降雨集流渗灌装置,通过室内土箱试验,以降雨量作为控制因子,研究不同雨量条件下径向和垂向土壤水分的运动特征。结果表明:随雨量增加累计入渗量逐渐增大,入渗速率逐渐减小;不同雨量条件下土壤含水率增量在垂向0~40 cm范围内随土层深度的增加呈先增加后减小的趋势,径向沿距渗灌器距离的增加逐渐减小;灌水结束24 h后土壤水分高含水率区主要分布在垂向20~40 cm和径向0~20 cm,湿润体大致呈半椭球体;集流渗灌器明显提升了小降雨的利用,使经济林主要根系分布范围(20~60 cm)内,土壤含水率明显增加,有利于缓解经济林生育期缺水,促进其生长,该研究结果可为集流渗灌器在田间推广应用提供可靠的数据支撑。

基于平原区野外观测的土壤水分特征曲线推求与应用

为研究湿润平原区非饱和带土壤水分特征曲线以及土壤水分运动规律,探究其对区域水循环过程的影响,本研究在我国太湖流域平原区金坛野外试验基地进行了降雨量、蒸发量、土壤含水量、水势、地下水埋深等连续监测。基于水文数据深入分析了土壤水动态变化,结果表明地表以下0~0.4 m深度的土层是土壤水分变化最频繁剧烈的地带。采用VG模型反演出基于野外实测数据的土壤水分特征曲线(SWCC)参数并与实验室得到结果相对比,并利用反演得到的土壤水分特征曲线对典型降水事件进行数值模拟。研究表明基于野外数据的土壤水运动模拟效果更优,较好地验证了野外观测曲线模型的精度与可靠性,为太湖流域平原区土壤水运动和产流计算提供了可靠的理论依据。

Numerical Simulation of Preferential Flow of Contaminants in Soil

A simple modeling approach was suggested to simulate preferential transport of water and contaminants in soil. After saturated hydraulic conductivity was interpolated by means of Krige interpolation method or scaling method, and then zoned, the locations where saturated hydraulic conductivity was larger represented regions where preferential flow occurred, because heterogeneity of soil, one of the mechanisms resulting in preferential flow, could be reflected through the difference in saturated hydraulic conductivity. The modeling approach was validated through numerical simulation of contaminant transport in a two-dimensional hypothetical soil profile. The results of the numerical simulation showed that the approach suggested in this study was feasible.