Land area that drains water to a particular stream, river or lake that can be identified by tracing a line along the highest elevations between two areas on a map, often a ridge, and may encompass a number of smaller watersheds (micro-watersheds) that ultimately combine at a common point.
University of Bern, Centre for Development and Environment (CDE), Knowledge Management for Integrated Watershed Management and Disaster Risk Reduction (17.4.2015).
Also known as drainage areas or river basins, watersheds are the zones from which rain or melting snow drains downhill into a river, lake, dam, estuary, wetland, sea or ocean. A watershed can be as large as several thousand square kilometres (as in the case of major river basins), or as small as a few hectares (as in the case of farm microwatersheds). Smaller watersheds are nearly always part of a larger watershed or river basin.
The term "catchment" is more commonly used by UK water authorities and academics, the term "watershed" is more common in the US and Canada. The terms are often used synonymously in development literature. Ensure that there is no confusion with the \horiginal meaning\s of "watershed" (divide between two catchments).
Based on SDC, Water [Glossary](https://www.collaboration.eda.admin.ch/en/Documents/COO.2011.100.11.865247.pdf), Watershed (17.4.2015).