Drainagegebied

Drainagegebied is the land area where precipitation and other water inputs drain toward a common outlet, such as a river, lake, estuary, or coastal basin. In Dutch usage it is often synonymous with afwateringsgebied or catchment area. The boundary of a drainagegebied is defined by a watershed or waterscheid line, which separates it from neighboring basins and follows the highest terrain, such as ridges and hills.

Within a drainagegebied, water moves through complex pathways that include surface runoff, streams and rivers, and groundwater flow. The hydrological processes in the basin involve infiltration, percolation into groundwater, storage in surface water bodies, evapotranspiration, and eventual discharge at the basin outlet. Land use, soil type, vegetation, and topography all influence the timing and amount of runoff.

Drainagegebieden vary greatly in size and can range from small catchments draining to a ditch or channel to large river basins spanning multiple regions or countries. Mapping and delineation are typically done using topography, hydrological data, and digital elevation models to support water resource management and flood risk assessment.

The concept is central to water resource planning and environmental management. It underpins flood forecasting, drought preparedness, and the allocation of freshwater, as well as the monitoring of nutrient and pollutant transport. In Europe and elsewhere, drainagegebied management is often integrated into basin-wide strategies and policies, such as those under comprehensive water frameworks and river basin management plans.