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Terms & Synonyms

Catchment Area

Official WHO Definition

A catchment - or drainage basin - is a discrete area of land which has a common drainage system. A catchment includes both the water bodies that convey the water and the land surface from which water drains into these bodies (UNEP et al. 1997). Please refer to drainage basin or river basin.

A catchment is a discrete area of land which has a common drainage system. The surface water catchment is defined by the topography of the land. This may not coincide, however, with any associated groundwater catchment (which is influenced by the underlying strata).Each drainage basin is separated topographically from adjacent basins by a ridge, hill or mountain, known as a water devide. The nature of the catchment (topography, soil strata) determines its hydrological characteristics, which in turn, are major determinants of its overall ecology.Catchment management plans are designed to cover a catchment of a river and its tributaries and any associated groundwater flows. In terms of the impact of activities within them, catchments are largely self-contained, manageable units, although any management activities can affect downstream areas.Experience gained in some countries suggests that catchment planning plays an essential role in setting water quality objectives. It provides the context in which the demands of all water users can be balanced against water quality requirements. Catchment planning also provides the mechanism for assessing and controlling the overall loading of pollutants within whole river catchments and, ultimately, into the sea, irrespective of the uses to which those waters are put. The need for "catchment accountability" is becoming increasingly important in order to ensure that both national and international requirements to reduce pollutant loadings are properly planned and achieved (UNEP et al. 1997).

Other Definitions

A catchment is an area of land that collects water, which drains to the lowest point in the area which could be either a lake, a dam, or the sea. Rain falling on the land will make its way to this lowest point, via creeks, rivers and stormwater systems.

As well as rivers, creeks, lakes and dams, a catchment also includes groundwater, stormwater, waste water, and water-related infrastructure.

The area within which water drains to a particular water source such as a river, lake or reservoir and which may also recharge an aquifer.


Interpretations and Explanations


UNEP, Water Supply & Sanitation Collaborative Council, and World Health Organization, 1997. Water pollution control: a guide to the use of water quality management principles, E & FN Spon, London

WHO Lexicon page (translations and examples)

COHRE Manual on the Right to Water and Sanitation

See also

External Resources

WHO Guidelines for drinking-water quality, 3rd ed

UNESCO Water quality assessments: a guide to the use of biota, sediments, and water in environmental monitoring

WHO Water quality monitoring: a practical guide to the design and implementation of freshwater quality studies and monitoring programmes

WHO Water quality: Guidelines, standards and health


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