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A · B · C · D · E · F · G · H · I · J · K · L · M · N · O · P · Q · R · S · T · U · V · W · X · Y · Z   entire Web this site drainage The runoff of water from an area, either naturally or, in agriculture, under artificial control. In nature, drainage generally takes the form of a pattern of streams, which feed rivers and lakes and flow, usually, to the sea (see water cycle). An area all of whose rainwater drains into a particular body of water is called a watershed or catchment basin (see groundwater). Systems of artificial drainage depend on on the nature of the soil, as well as local topography. Two main systems are used: surface and subsurface. Surface systems usually comprise a pattern of ditches; subsurface systems a pattern of conduits and tunnels. These usually lead to a natural stream. See also irrigation. Related categories    • AGRICULTURE    • ECOLOGY AND THE ENVIRONMENT Also on this site: Encyclopedia of Science Transport Concepts & Designs (partner site) BACK TO TOP