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本文依据水分运动的扩散方程和溶质迁移的对流弥散方程,探讨了实验条件下两种红壤的非饱和水动力迁移特征.实验采用均质水平土柱稳压供水或低浓度的KCl溶液.应用有限差分法建立了一维非饱和水分和溶质迁移的数值模型,在实验确定的初始和边界条件下得到计算机模拟结果,与实测值比较表明,模拟值能很好地预测土壤剖面的水分动态变化.但在预测氯离子剖面分布时出现了较大的偏差.这种偏差可能由于土壤中存在着与入渗溶液进行溶质交换而相对不活动的“非活动水”以及溶质水动力弥散系数的计算不准确所致.
In this paper, based on the diffusion equation of water movement and the convection-dispersion equation of solute transport, the characteristics of unsaturated hydraulic migration of two red soils under experimental conditions are discussed. The experiment uses homogeneous soil column to supply water or KCl solution with low concentration. Difference method was used to establish the numerical model of one-dimensional unsaturated water and solute transport. Computer simulation results were obtained under the experimental initial conditions and boundary conditions. Comparing with the measured data, the simulated data can predict the dynamic changes of soil moisture profile well. However, there was a large deviation in the prediction of the distribution of chloride ion profiles, which may be due to the existence of “inactive water” which is relatively inactive in the soil with solute exchange with the infiltration solution and the calculation of the dynamic dispersion coefficient of solute water Accurate due.