Simulation of soil water and heat transfer under subsurface irrigation considering spatial differences in soil hydraulic properties

Abstract

Enhanced irrigation efficiency is necessary to address water shortages, and precise estimation of soil water movement by simulation models is essential. Previous studies have suggested that soil hydraulic properties, which are important factors of soil water movement, differ spatially in the horizontal and vertical directions. However, most of studies have estimated soil water movement by considering soil hydraulic properties only along the soil profile. In the present study, we defined soil hydraulic conductivity and soil water retention as soil hydraulic properties, and conducted soil water movement simulations considering the spatial (horizontal and vertical) differences in soil hydraulic properties. The simulation model also estimated soil temperature to include water vapor transfer in the estimation of soil water movement. We validated the model by comparing simulated and observed results from a pot experiment, and comparing the soil water movement and soil temperature in two cases of applying the soil hydraulic properties: spatial application and vertical application. The results showed that the simulated soil temperature differed from the observed values due to the uniform application of thermal conductivity of soil. Our findings indicated that the differences in soil water movement between both cases increased with the number of irrigations. Discipline: Agricultural Engineering.