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基于有限元(FEM)和改进的积分型Richards方程解法(IRE方法)对蒸发条件下5种土体土壤水分响应进行了研究。数值实验结果表明:在土壤表面潜在蒸发量0.50 cm/d的情况下,5种土体土壤含水率变化曲线均呈现单拐点两阶段的特点,拐点出现在地表下20cm左右,拐点上部区域曲线曲率大于下部区域,两阶段的划分以15d左右为界,前阶段比后阶段的土壤水分变化快;蒸发模拟结果很好的证明了蒸发三阶段理论。总蒸发量和下边界排水量与土壤结构密切相关,而总水量变化量和变化率与土壤质地有关。IRE方法与FEM模拟结果基本一致,解法相对简单,模拟结果可靠性高。
The soil moisture responses of five soils under evaporative conditions were studied based on the finite element method (FEM) and the improved integral Richards equation solution (IRE method). The results of numerical experiments show that the curves of soil water content of five soil types show a two-stage single turning point under the potential evaporation of 0.50 cm / d. The inflection point appears about 20 cm below the ground surface, and the curve curvature Which is larger than the lower region. The division of the two stages is about 15 days, and the change of soil moisture in the first stage is faster than that in the latter stage. The simulation of evaporation shows that the three-stage theory of evaporation is good. Total evapotranspiration and lower boundary drainage are closely related to soil structure, while the total amount and rate of change of water quantity are related to soil texture. IRE method and FEM simulation results are basically the same, the solution is relatively simple, the simulation results of high reliability.