Application of a 2D Hydrodynamic Numerical Model for Heavy Precipitation-Induced Soil Erosion

Abstract Soil erosion, particularly when intensified by heavy precipitation, is a natural process and a persistent challenge in agricultural management. To date, this problem has been addressed using existing erosion models. However, these models often rely on simplified hydraulic approaches, whereas two-dimensional (2D) hydrodynamic numerical models are state-of-the-art for overland flow simulations. In this study, the combination of a 2D model and a soil erosion approach allowed for a more precise consideration of the hydraulics. The Govers approach was used with the 2D HydroAS model and evaluated using experimental plot data and naturally occurring field-scale erosion data, sourced from the literature. Results indicate that the combined model simulated sheet erosion and produced reasonable estimates for small rills using the Govers transport capacity approach. However, larger rills require calibration of this method. Additionally, the resolution of the digital elevation model (0.25 m) used as the basis for the simulation was of great importance to avoid overestimating smaller rills. Sensitivity analysis revealed that these smaller rills were particularly influenced by the input grain diameter and surface roughness. Comparisons with other erosion models underscore that incorporating an improved hydraulic approach and adapting the topography at each simulation time step enhances estimation of the spatial distribution and quantity of erosion of the rills. Knowledge about the occurrence and quantification of rill erosion can help planners develop geoecological solutions for flooding and erosion.