An expanse of water can be a form of standing water such as a lake (incl. reservoirs) as well as running water such as rivers, canals and irrigation ditches. Similarly, harbour basins are classified as expanses of water. Modelling of such waters within the ATKIS Basis-DLM can be either as linear or geometrical objects. Expanses of water are geometrically defined by the lines of their banks at average water level or average high water tide. The Monitor of Settlement and Open Space Development takes account of the width of linearly modelled expanses of water.
Seas or shallow bays are only included when they fall within administrative boundaries (usually the exception).