Surface runoff

runoffagricultural runoffrun-offstormwater runoffwater runoffland runoffoverland flowrunoff waterstorm water runoffrun off
Surface runoff (also known as overland flow) is the flow of water that occurs when excess stormwater, meltwater, or other sources flow over the Earth's surface.wikipedia
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Stormwater

storm waterstormwater managementcontrols
Surface runoff (also known as overland flow) is the flow of water that occurs when excess stormwater, meltwater, or other sources flow over the Earth's surface.
Stormwater can soak into the soil (infiltrate), be stored on the land surface in ponds and puddles, evaporate, or runoff.

Water

H 2 OHOliquid water
Surface runoff (also known as overland flow) is the flow of water that occurs when excess stormwater, meltwater, or other sources flow over the Earth's surface.
Water moves continually through the water cycle of evaporation, transpiration (evapotranspiration), condensation, precipitation, and runoff, usually reaching the sea.

Nonpoint source pollution

nonpoint sourcenonpoint sourcesnon-point sources
Runoff that occurs on the ground surface before reaching a channel can be a nonpoint source of pollution, as it can carry man-made contaminants or natural forms of pollution (such as rotting leaves).
Nonpoint source water pollution affects a water body from sources such as polluted runoff from agricultural areas draining into a river, or wind-borne debris blowing out to sea.

Drainage basin

watershedbasincatchment area
The land area producing runoff that drains to a common point is called a drainage basin.
The drainage basin includes all the surface water from rain runoff, snowmelt, and nearby streams that run downslope towards the shared outlet, as well as the groundwater underneath the earth's surface.

Water cycle

hydrological cyclewaterhydrologic cycle
Surface runoff is a major component of the water cycle.
The water moves from one reservoir to another, such as from river to ocean, or from the ocean to the atmosphere, by the physical processes of evaporation, condensation, precipitation, infiltration, surface runoff, and subsurface flow.

Urban runoff

runoffstormwater runoffletting it flow into the sewers
In addition to causing water erosion and pollution, surface runoff in urban areas is a primary cause of urban flooding, which can result in property damage, damp and mold in basements, and street flooding.
Urban runoff is surface runoff of precipitation created by urbanization.

Channel (geography)

channelchannelsshipping channel
Runoff that occurs on the ground surface before reaching a channel can be a nonpoint source of pollution, as it can carry man-made contaminants or natural forms of pollution (such as rotting leaves).
Overland flow is a primary factor in channel initiation where saturation overland flow deepens to increase shear stress and begin channel incision.

Soil erosion

erosionErodedsoil erosion by water
It is the primary agent of soil erosion by water.
Rainfall, and the surface runoff which may result from rainfall, produces four main types of soil erosion: splash erosion, sheet erosion, rill erosion, and gully erosion.

Snowmelt

snow meltmeltwatermelt snow
Snow and glacier melt occur only in areas cold enough for these to form permanently.
In hydrology, snowmelt is surface runoff produced from melting snow.

Flood

floodingfloodsflood control
In addition to causing water erosion and pollution, surface runoff in urban areas is a primary cause of urban flooding, which can result in property damage, damp and mold in basements, and street flooding.
Floods can happen on flat or low-lying areas when water is supplied by rainfall or snowmelt more rapidly than it can either infiltrate or run off.

Soil

soilsdirtsoil moisture
This can occur when the soil is saturated to full capacity, and rain arrives more quickly than soil can absorb it.
Topography determines the rate of precipitation or runoff and rate of formation or erosion of the surface soil profile.

Infiltration (hydrology)

infiltrationinfiltrateinfiltration capacity
This occurs when the rate of rainfall on a surface exceeds the rate at which water can infiltrate the ground, and any depression storage has already been filled.
If the precipitation rate exceeds the infiltration rate, runoff will usually occur unless there is some physical barrier.

Erosion

erodedglacial erosioneroding
It is instead forced directly into streams or storm water runoff drains, where erosion and siltation can be major problems, even when flooding is not. There are four main types of soil erosion by water: splash erosion, sheet erosion, rill erosion and gully erosion.
In earth science, erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location (not to be confused with weathering which involves no movement).

Water pollution

pollutionpollutedwater
When anthropogenic contaminants are dissolved or suspended in runoff, the human impact is expanded to create water pollution.
Non-point sources are more diffuse, such as agricultural runoff.

Water quality

qualitywaterchemical hydrology
A 2008 report by the United States National Research Council identified urban stormwater as a leading source of water quality problems in the U.S.
Industrial and commercial activities (e.g. manufacturing, mining, construction, transport) are a major cause of water pollution as are runoff from agricultural areas, urban runoff and discharge of treated and untreated sewage.

Rill

rillswater channel
There are four main types of soil erosion by water: splash erosion, sheet erosion, rill erosion and gully erosion.
In hillslope geomorphology, a rill is a shallow channel (no more than a few tens of centimetres deep) cut into soil by the erosive action of flowing water.

Soil conservation

soilsoil protectionconservation
Reduced crop productivity usually results from erosion, and these effects are studied in the field of soil conservation.
Furrows move left and right to maintain a constant altitude, which reduces runoff.

Robert E. Horton

HortonRobert Elmer HortonRobert Horton
This is called flooding excess overland flow, Hortonian overland flow (after Robert E. Horton), or unsaturated overland flow.
Horton is well known for his study of maximum runoff and flood generation.

Turbidity

turbidNephelometric Turbidity UnitNTU
Erosion of silty soils that contain smaller particles generates turbidity and diminishes light transmission, which disrupts aquatic ecosystems. When surface waters are used as potable water supplies, they can be compromised regarding health risks and drinking water aesthetics (that is, odor, color and turbidity effects).
Human activities that disturb land, such as construction, mining and agriculture, can lead to high sediment levels entering water bodies during rain storms due to storm water runoff.

Fish kill

fish killsfish die-offdie-offs
Contaminated surface waters risk altering the metabolic processes of the aquatic species that they host; these alterations can lead to death, such as fish kills, or alter the balance of populations present.
Fish kills may also occur due to the presence of disease, agricultural runoff, sewage discharges, oil or hazardous waste spills, hydraulic fracturing wastewater, sea-quakes, inappropriate re-stocking of fish, poaching with chemicals, underwater explosions, and other catastrophic events that upset a normally stable aquatic population.

Drinking water

potable waterpotableclean water
When surface waters are used as potable water supplies, they can be compromised regarding health risks and drinking water aesthetics (that is, odor, color and turbidity effects).
Inorganic minerals generally enter surface water and ground water via storm water runoff or through the Earth's crust.

Fertilizer

fertiliserfertilizersnitrogen fertilizer
Man-made contaminants in runoff include petroleum, pesticides, fertilizers and others.
High application rates of nitrogen-containing fertilizers combined with the high water solubility of nitrate leads to increased runoff into surface water as well as leaching into groundwater, thereby causing groundwater pollution.

Eutrophication

eutrophiceutrophicatedeutrophied
Surface runoff occurring within forests can supply lakes with high loads of mineral nitrogen and phosphorus leading to eutrophication.
Due to clearing of land and building of towns and cities, land runoff is accelerated and more nutrients such as phosphates and nitrate are supplied to lakes and rivers, and then to coastal estuaries and bays.

Estuary

estuariesestuarinetidal estuary
Any remaining surface water eventually flows into a receiving water body such as a river, lake, estuary or ocean.
Estuaries tend to be naturally eutrophic because land runoff discharges nutrients into estuaries.

Gully

gulliesgully erosiongulley
There are four main types of soil erosion by water: splash erosion, sheet erosion, rill erosion and gully erosion.
This erosion can result from interflow as well as surface runoff.