subsurface storm flow

Subsurface storm flow is a hydrological process where water infiltrates the soil and moves laterally downslope, typically above the main groundwater level, before reaching a stream channel. This type of flow is most common in humid regions with steep, forested slopes and permeable surface soils. It occurs when the soil becomes saturated to a certain depth, allowing water to move rapidly through preferred pathways.123

Unlike surface runoff, which is faster and more prone to erosion, subsurface storm flow is slower and contributes to water saturation in the upper soil profile. This process is crucial for sustaining streamflow, especially during and immediately after precipitation events, and plays a role in the translocation of dissolved substances through the soil.23