Overland Flow
… Overland flow or surface flow is that precipitation that either fails to penetrate into the soil or that resurfaces at a later point due to subsurface conditions.
… often referred to as "sheet" flow.
… for the purposes of this discussion, overland flow (sheet and surface flow, as well) is considered to be the flow that has not had a chance to collect and begin to form gullies, rills, swales