A new concept of modelling water infiltration in a sandy loam soil

Abstract

Infiltration is the process of water entering the soil from the surface into its layers, within the pores, and between the particles. This process determines the soil's ability to absorb water and significantly impacts the selection of the appropriate irrigation method. This research aims to apply a new approach to modeling the infiltration process in sandy loam soil, to calculate cumulative infiltration, and then develop an equation that can be used to estimate wetting front depth based on the cumulative infiltration and the physical properties of the soil. Nine laboratory experiments were conducted on a homogeneous sandy loam soil, involving three initial moisture contents and three ​​bulk densities. The infiltration process was then modeled using six popular infiltration models (Kostiakov, modified Kostiakov, revised modified Kostiakov, Philip, Horten, and Soil Conservation Service “SCS”). The Microsoft Excel Solver tool was used to find the parameters of these models. The performance of these models was compared using three statistical criteria: sum of square errors SSE, determination coefficient R², and root mean square error RMSE. Results showed that the Revised Modified Kostiakov model achieved the best performance, with statistical values ​​of 152.49 (SSE), 0.9999 (R²), and 0.882 (RMSE). The Horten model performed weakest, with values ​​of 439.67, 0.9985, and 1.498, respectively. Analyses indicated an inverse relationship between initial moisture content, bulk density, and cumulative infiltration depth. In contrast, a direct relationship was observed between initial moisture content and wetting front advance.