自然条件下土壤不饱和区中水含量分布模拟

采用International Ground Water Modeling Center (IGWMC)推出的模拟软件——HYDRUS-2D，对由于降雨、蒸发和植物蒸腾作用的影响造成土壤不饱和区的水含量分布的变化进行模拟计算，利用文献中的土壤水力特征参数和现场的实际降雨量作为计算基础，并且把植物根系分布造成的蒸腾作用考虑进去，进行二维不饱和区域中的模拟计算，模型采用有限元方法求解水含量的方程——Richard方程，降雨、蒸发和蒸腾作用均作为随时间变化的边界条件，植物根系对水分的吸收作为水传递方程的源汇项，模拟的时间长度是70d，在模拟的区域中竖直方向上5、10、15cm3个不同深度分别设置了模拟的数据观测采样点。模拟的结果表明，越是靠近表面处的水含量对于气候变化越敏感，变化也越剧烈，与文献中的数据进行对比，模拟结果与实际现场的测试数据比较吻合，可见运用HYDRUS-2D进行模拟可以较好地反映真实的情况，可以作为实际运用的一种预测手段。

HYDRUS- 2D Modeling of Water Contents in Soils Under Climatic Conditions

Under the climatic conditions soil water content has been modeled using HYDRUS- 2D, which was distributed by the International Ground Water Modeling Center (IGWMC). In the modeling, rainfall, evaporation and water uptake by plant roots have been taken into account. The governing flow and transport equations are solved numerically using Galerkin- type linear finite element schemes. The soil type chosen was a sandy loam, which character was got from the other literatures. The time of modeling was 70 days and at different depth in the domain three observation nodes have been defined. The water content of the observation node more near the surface was more sensitive to the variety climatic condition. In the contrast with the field data in the literature, the result of soil water modeling gained was satisfied.