A watercourse is a geometrically limited body of running water on the mainland that collects rainfall or water issuing from natural springs and transports this into a sea or lake or into a waterway system located in natural or artificial land depressions. In this way watercourses serve to supply or remove water, or can be used for shipping by means of an artificially constructed waterway of one or several sections, each of which have a uniform water level. A watercourse is classified as a form of open space.

Watercourses of width larger than 12 m are modelled as spatially-extended objects. Narrower courses are modelled as lines, which requires buffering with the following three width classes: 

- BRG=3 with buffer distance 1.50 m,

- BRG=6 with buffer distance 4.50 m,

- BRG=12 with buffer distance 9.00 m.

There is no buffering in the case of underground watercourses or courses which dry up during the year.

[Source: AdV (2008): GeoInfoDok, ATKIS-Objektartenkatalog Basis-DLM, Version 6.0]