不同斥水程度黏壤土一维入渗特性试验研究

Experiment on one-dimensional infiltration characteristics of clay loam soil with different water repellency

采用人工配置的5种斥水程度等级的黏壤土,通过室内一维积水入渗试验,探究了斥水程度对黏壤土湿润锋运移、累积入渗量、入渗率、土壤剖面含水率以及水分再分布的影响,分析了不同斥水程度土壤入渗条件下入渗模型的适用性.结果表明:随着斥水程度增大,土壤入渗率变慢,湿润锋运移相同距离所需要的时间显著增加,其中运移到40cm时,强斥水土壤比亲水土壤的运移时间增加了63%;随着斥水程度增大,累积入渗量减小,入渗结束时强斥水土壤比亲水土壤的累积入渗量减小了27%;土壤的入渗率也随着斥水程度增大而逐渐减小,强斥水土壤的稳定入渗率为亲水土壤的37%;随着斥水程度增大,土壤剖面含水率减小,且经过相同时间的水分再分布,土壤剖面含水率的变化量也随之减小;幂函数可以很好地模拟湿润锋运移距离和累积入渗量随时间的变化过程;对弱斥水土壤而言,Philip模型和Kostiakov模型对入渗率与时间的关系有较高的拟合度,而强斥水土壤则Kostiakov模型更为适用.研究可为斥水土壤的入渗提供理论基础.

To explore the effect of water repellency on the infiltration characteristics of clay loam,indoor water infiltration experiment was conducted.There were five kinds of clay loam with different water repellency degrees.The investigated soil water infiltration characteristics included wetting front,infiltration rate,cumulative infiltration,soil moisture and water redistribution.The applicability of three soil infiltration empirical models under different water repellency conditions was analyzed.The results show that the soil infiltration rate is reduced,and the time required for wetting front migration is increased significantly with increasing water repellency.The time for the wetting front to travel the same distance is increased significantly,especially the time for 40 cm travelling distance in soil with strong repellency is 63% longer than that in hydrophilic soil.With increasing water repellency,the cumulative infiltration is reduced and the cumulative infiltration of S4 is decreased by 27% compared with S0 at the end of infiltration.The infiltration rate is also decreased with the increase of water repellency,and the saturated infiltration rate is 37% of that in hydrophilic soil.Both the moisture of soil profile and the change in moisture of redistributed soil profile in the same time are decreased with increasing water repellency.The power function model can simulate the migration process of wet front and the variation of cumulative infiltration with time.For the soil with slight repellence,the Philip model and the Kostiakov model are subject to a better accuracy in fitting the relationship between infiltration rate and time,while the Kostiakov model is even more suitable for the soil with strong repellency.The study can provide a basis for the infiltration theory of repellent soil.