Sheet flow is a peculiar term used by water professionals to characterize water that flows unchecked over the landscape, but with no defined channels. In effect, it goes everywhere and nowhere. Forested filter strips capture sheet flow, slowing runoff velocity, filtering out sediment and other pollutants, and reducing flow via evapotranspiration and infiltration. This fact sheet offers rough design guidelines.
Urban Watershed Forestry Manual. Part 2: Conserving and Planting Trees at Development Sites, 2006View Resource