Simulation of soil water and salt transport with sand column in coastal saline soil based on COMSOL

In the paper, transport of water and Cl- under leaching was 2D-digitally simulated with COMSOL Multi-physics. In a two-dimensional transient cross-sectional model. COSMOL was used to investigate water and solute transport in the soil column coupled with variable sand column forms, with "a" denoting no sand column, "b" with one vertical middle sand column, "c" with one long Slanted sand column, "d" with two long Slanted X-shaped sand columns. The parameters of the model were primarily based on the soil physical properties measured at coastal clay loam saline soil in Tianjin. The simulation results showed that, given same initial and same boundary conditions, sand column increased the transport efficiency of water and salt, which depends on the position and angle of sand column accordingly. The slanted columns were overall superior to the vertical ones in transport efficiency. In sum, "d" was the best type, "c" was the second best and "b" was the third, according to the efficiency of salt leaching and the efficiency of the utilization of water resources.