LAUSR

Preferential flow in soils contributes to water and contaminant leaching to groundwater and subsurface drains. At practical scales, preferential flow is often neglected due to the lack of consensus or guidance on how to simulate this process. Dual‐permeability (DP) approaches are a standard, but their applicability in practice is limited by the large number of parameters involved. The source‐responsive (SR) model simulates preferential flow as flow films along the walls of macropores that interact with the soil matrix. The objective of this study was to evaluate the ability of the SR model and a DP model with calibration limited to macropore parameters to simulate hydrologic variables of interest for practical applications. Infiltration experiments were conducted in a 150‐cm‐long by 50‐cm‐wide by 40‐cm‐deep soil column with vertical artificial macropores, with preferential flow being the most prevalent flow process. Two macropore configurations and various rainfall rates were tested. The DP model provided relatively accurate predictions of the bottom drainage rates, but inaccurate soil parameter estimates resulted in poor predictions of matrix flow. Critical limitations in the SR model formulation were highlighted, and the model was revised. The refined SR model provided accurate predictions of bottom drainage rates and water contents under steady‐state rainfall. The DP model with a reduced calibration appeared valid to estimate subsurface fluxes with negligible matrix flow. The SR model applicability is limited to steady‐state scenarios with negligible matrix flow. Critical developments are needed for the SR model to be applicable in practice.