vattenavrinningsområde
Vattenavrinningsområde, also known as a drainage basin or watershed, is a geographical area where all surface water from precipitation, such as rain and snowmelt, converges to a single point at a lower elevation, typically the exit of the basin, or the inflow to a river, stream, lake, reservoir, estuary, wetland, sea, or ocean. These areas are defined by topographic divides, which are essentially the highest points surrounding the basin. Water flows downhill, following the path of least resistance, and all the water that falls within a specific divide will eventually drain towards the same outlet.
The size of a vattenavrinningsområde can vary enormously, from a few square meters for a small hillside