run off

SURFACE WATER

Surface runoff is the flow of water that occurs when excess storm water, melt water, or other sources flows over the earth's surface.

Surface runoff can be generated either by rainfall, snowfall or by the melting of snow, or glaciers.

This is a major component of the water cycle or the hydrological cycle.

Runoff

Effects of surface runoffErosion and deposition

4 types of soil erosion by water:

•Splash erosion•Sheet erosion•Rill erosion •Gully erosion 

Splash erosion Is the result of mechanical collision of raindrops with the soil surface: soil particles which are dislodged by the impact then move with the surface runoff.

Sheet erosion Is the overland transport of sediment by runoff without a well defined channel. Soil surface roughness causes may cause runoff to become concentrated into narrower flow paths

Is the small but well-defined channels which are formed. These channels can be as small as one centimeter wide or as large as several meters. If runoff continue to incise and enlarge rills, they may eventually grow to become gullies. Gully erosion can transport large amounts of eroded material in a small time period.

Rill erosion

Land use development controls aimed at minimizing impervious surfaces in urban areas

Erosion controls for farms and construction sites

Flood control and retrofit programs, such as green infrastructure

Chemical use and handling controls in agriculture, landscape maintenance, industrial use, etc.

Mitigation and treatment

The measurement of runoff, in the field, is generally carried out using current meters and calibrated or rated channel cross sections, flumes or standardized weirs, together with water level readings, often by automatic recorders, to give a continuous height record which can be correlated to flow.

Runoff was measured from small (1.0-6.1 m2 ) plots encompassing sections of terrace risers and beds (Artificial Boundary Erosion Plots).

Measurement and mathematical modeling

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PAUL JOHN C. LULUmabadBSCE 5-2