Precipitation, snow melt, or irrigation in excess of what can infiltrate the soil surface and be stored in small surface depressions; runoff is a major transporter of non­point source pollutants.

That portion of rainfall that is not immediately absorbed into the soil and becomes overland flow

Precipitation that exceeds the infiltration capacity of soils and reaches streams relatively fast, via the land surface. This produces higher or peak flows immediately following storm events.

Water that runs across the top of the land without infiltrating into the soil.

The process of precipitation moving across saturated or impervious soils.

The portion of rainfall, irrigation water or wastewater that does not infiltrate into the soil.

That part of the runoff that travels over the soil surface to the nearest stream channel. It also is defined as that part of the runoff of a drainage basin that has not passed beneath the surface following precipitation.

Precipitation, snowmelt, or irrigation water in excess of what can infiltrate the soil surface and be stored in small surface depressions; a major transporter of nonpoint source pollutants.

Water that flows over the surface of the land as a result of rainfall or snowmelt. Surface runoff enters streams and rivers to become channelized stream flow.

water that flows off the land, eventually to an aquatic ecosystem

That portion of runoff which travels over the ground surface and through channels to reach the basin outlet. Surface runoff is composed of overland flow and streamflow.

See overland flow.

water flowing along the ground into rivers, lakes, and oceans

Precipitation that flows onto the surfaces of roofs, streets, the ground, etc., and is not absorbed or retained by that surface but collects and runs off.

The portion of rainfall that moves over the ground toward a lower elevation and does not infiltrate the soil

Water flowing off the land into bodies of surface water. See reliable runoff.

Water flowing off the lower end of the field.

Water than travels downhill overland until entering a defined channel.

Surface runoff is water, from rain, snowmelt, or other sources, that flows over the land surface, and is a major component of the water cycleRobert E. Horton, The Horton Papers (1933)Keith Beven, Robert E. Horton's perceptual model of infiltration processes, Hydrological Processes, Wiley Intersciences DOI 10:1002 hyp 5740 (2004).