Two‐dimensional modeling of flow and transport in the vadose zone with surfactant‐induced flow

Surface‐active solutes (surfactants) can induce capillary pressure gradients and water fluxes within the vadose zone. Common numerical models do not account for the effects of surfactant‐induced capillary pressure gradients on unsaturated flow and transport. We modified the variably saturated flow and transport model HYDRUS‐2D [Simunek et al., 1999] to incorporate the effects of surfactant concentration‐dependent changes to surface tension and …