drænage

Dränage is a term used in Swedish for drainage, the process of removing excess water or other liquids from an area, system, or body to prevent accumulation, damage, or infection. In civil engineering and land management, dränage aims to control water on the surface and beneath the ground, improving stability and usability of land and infrastructure.

In construction and land management, surface drainage removes water from the surface using ditches, channels, swales, and grading, while subsurface drainage uses perforated pipes, gravel, and filters to lower the water table and improve soil conditions. Typical installations include drains, outlets, and geosynthetics. Design depends on soil type, slope, rainfall, groundwater, and land use; proper maintenance includes clearing debris, inspecting outlets, and replacing failed components.

In medicine, dränage refers to the removal of fluids from wounds, cavities, or body spaces. Methods include passive drains, such as Penrose drains, and active suction drains, such as Jackson–Pratt or chest tubes. Drainage aids healing by removing pus, serum, or blood, preventing accumulation and infection. Care involves monitoring volume and appearance, securing the drain, and preventing blockages; risks include infection, tissue irritation, and drain displacement.

Urban and environmental drainage encompasses networks of pipes, culverts, and retention basins to convey water away and reduce flooding. There is growing emphasis on sustainable drainage systems (SuDS) or low-impact development, which combine storage, infiltration, and discharge controls to mimic natural hydrology and reduce pollutant loads.