Numerical Simulations of Soil Salt Transport in the Irrigation Area of Lower Reaches of Yellow River

Abstract

This paper presents numerical simulations regarding the transport characteristics of soil salt. It has been recognized in recent years that the growth and output of crops in the irrigation area of the lower reaches of the Yellow River are affected by the decreased fertility of soil as a result of the transport of soil salt, due to the long-term farming, fertilization of farmland which contains a high proportion of sands. Accordingly, numerical simulations by Hydrus are carried out, in which, based on the similarity principle, two-dimensional convection-diffusion partial-differential governing equations of unsteady flow in saturated-unsaturated porous media are applied to depict the motion parameters’ spatial variability of soil water in the irrigation area. And the van Genuchten equation is adopted to express the relationship between volumetric water content and soil hydraulic conductivity and negative soil water pressure. The irrigation basin of the People’s Victory Canal, which is downstream of the Yellow River, is investigated in detail as an example. The findings revealed that soil salt in the irrigation region is transferred by water diffusion, with irrigation and fertilization being the primary causes of downward migration and salt accumulation. It benefits the soil in irrigation areas and protects groundwater.