Analytical Mathematical Model of Chemical Suffosion while Washing Saline Soils

The problem of the quantitative assessment and prediction of suffosion-induced subsidence in saline soils and sediments is relevant for irrigation, washing of saline soils, and increasing amounts of domestic and industrial effluents. Based on the solution of the convective diffusion equation and taking into account the dissolution of salts of the solid phase, the presented mathematical analytical model can be used to solve both the direct problem of predicting desalinization of the soil profile and finding the soil washing rate and time required for washing of a given thickness of soil to a certain salinity level and the inverse problem of determining the hydrodynamic dispersion parameter and the diffusivity. This model is based on the concept of the average integral value of the concentration of soil solution (i.e., its average concentration in the entire calculated soil profile, but not in separate discrete layers) and the corresponding method for determining the dissolution rate of the salts in the solid phase of soils and sediments, which makes it possible to quantitatively calculate and predict the suffosion-induced compaction and subsidence of soils and dispersed sediments. Taking into account the ongoing processes in the real time, an analytical procedure was developed for finding the dissolution rate of salts. The suggested analytical solution of the convective-diffusive salt transfer can be applied to predict the redistribution of salts over time in water-saturated soil profile with surface salinization and deep groundwater table.