入渗、再分布和蒸发条件下一维土壤水运动的数值模拟

Mathematical Simulation of Soil Water Movement under Infiltration,Redistribution and Evaporation

采用数值法求解非饱和土壤水分运动的Richards方程可采用不同的初始和边界条件,实现复杂条件下水分运动过程的预测。在确定入渗、再分布及蒸发的初始和边界条件基础上,采用隐式差分格式列出差分方程,对垂直一维积水入渗、半无限土体再分布及半无限土体裸土蒸发的水分运动过程进行数值模拟,模拟结果与实测资料的比较表明,就入渗湿润锋、累积入渗量的时间变化趋势及入渗、再分布和蒸发的土壤含水率剖面而言,其实测值与计算值比较符合,说明采用的算法、水分特征曲线模型和其它参数都是合理的,该方法可用来描述水分运动特征。

Richard＇s equation developed for unsaturated soil water movement can be resolved with mathematical simulation methods, using different initial and boundary conditions to predict soil water movement process under complicated conditions. In this paper, based on determination of initial and boundary condition, implicit difference method was used to present difference equations in order to simulate soil water movement of one-dimensional ponded water infiltration, redistribution and evaporation mathematically. The comparison of simulation results with that of experiments showed that, as to the trend of wetting fronts with infiltration time, that of cumulative with infiltration time, as well as the soil moisture profiles of redistribution and evaporation, their observed values were fitted well with calculated ones, which indicated that the arithmetic and the related parameters used in the method was reasonable, this arithmetic may be well used to soil water movement.