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 catchment to thousands of square kilometers for major river systems. The characteristics of a vattenavrinningsområde, such as its geology, soil type, vegetation cover, and slope, significantly influence the amount and quality of water that flows through it. These factors affect how quickly water infiltrates the ground, how much surface runoff is generated, and the potential for erosion and sediment transport. Understanding vattenavrinningsområden is crucial for water resource management, flood control, and ecological studies, as they represent the fundamental units for managing water and its associated environmental processes.