Effect of unsaturated soil water transport function linearization for mulched drip irrigation

Water flow in the unsaturated zone is an important component of the water cycle. Linearized methods have been widely adopted to solve unsaturated flow problems described with Richards' equation, which is nonlinear. To better understand the effect of unsaturated soil water transport function linearization, this article presents an analytical study of a two-dimensional soil water flow system. Analytical solutions, experimental observations and numerical simulations were compared, and the results indicated that the soil water content variation trends were the same, but the values were a little different. The analytical solutions have a certain reference value for researching unsaturated water flow. However, the soil volumetric water content (SWC) results were sensitive to linearized water flow parameter variations in soil water diffusivity (D). The D changes with the SWC. The results showed that unsaturated water flow function linearization affected the analytical solution results essentially. As the nonlinear math problem was not solved, we recommend the numerical solution when more precise values are needed and complex conditions are considered.