层状红壤水分入渗特征试验与模拟

认识土壤结构对土壤水分运移影响是提高土壤水分利用效率和控制面源污染的重要基础.以容重为1.35和1.55 g/cm³的均质土及其组成的上松下紧层状土壤结构为对象,采用室内土柱恒定水头水分入渗试验和模型模拟相结合的方法,分析不同土层结构的水分入渗过程及水分再分布特征.结果表明,上松下紧的层状土壤积水入渗速率过程可明显分为上层入渗阶段和下层入渗阶段; 与均质土相比,层状土轻微降低了上层的入渗速率和提高了下层初始速率,但对下层的稳定入渗率影响不大.层状土壤可显著提高上层土壤含水量,且水分再分配过程在界面处发生了突变.采用HYDRUS-1D模型模拟层状土壤入渗水分再分布,直接组合均质的土壤水力参数模拟效果较差,需要对进气吸力进行参数优化.研究成果可为红壤地区土壤水分管理和污染防治提供理论支撑.

Experimental and simulation study on water infiltration characteristics of layered red soil

Analyzing the effect of soil structure on soil water transport is an important basis for improving soil water use efficiency and controlling non-point source pollution. In this paper, homogeneous soil with bulk density of 1.35 g/cm³ and 1.55 g/cm³ and its upper and lower tight layered soil structure are taken as the research objects to studied. The method of combining constant head water infiltration experiment by indoor soil columns and model simulation was used to analyze soil water infiltration process and water redistribution characteristics under different layer structure. The results show that the infiltration process of layered soil with soft top and dense bottom can be divided into upper infiltration stage and lower infiltration stage. Compared with homogeneous soil, the infiltration rate of the upper layer is reduced slightly and the initial rate of the lower layer is increases for layered soil, but has little effect on the stable infiltration rate of the lower layer. The layered soil can significantly improve the water content of the upper layer, and the water redistribution process has changed at the discontinuous mutation that occurs at the interface. When the HYDRUS-1D model is used to simulate soil moisture redistribution in the layered soil, the direct combination of homogeneous soil hydraulic parameters has poor simulation effect. If a satisfactory simulation result is needed, the parameters of the intake suction must be optimized. The research results can provide theoretical support for soil water management and pollution control in red soil areas.