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drainage basin — English
An area of land drained by one river and its tributaries. It is separated from the adjacent drainage basins by ridges of higher land. The boundary of a drainage basin is a watershed (see “watershed”). A drainage basin can be regarded as an open system with inputs (such as precipitation and the melting of snow or ice) that supply water to the drainage basin, and outputs (such as evapotranspiration and river run-off) that remove water from the system. Various processes take place in a drainage basin, namely interception, surface storage, infiltration, percolation, groundwater storage, groundwater flow, surface run-off (overland flow), channel storage and channel flow. Drainage basins have different shapes (morphometry), sizes and vastly different characteristics. The study of drainage basins is a specialisation field in a number of sciences, including Geography. (See “channelization”.)
