Snabbavrinningen

Snabbavrinningen is a term used in hydrology and soil science to describe rapid drainage of water from a soil profile or drainage network after a rainfall event or rise in groundwater. The concept emphasizes short lag times between input and discharge and is often associated with sharp runoff peaks.

Mechanisms behind snabbavrinningen include gravitational flow through preferential pathways such as macropores, cracks, and coarse-textured layers, as well as rapid pressure relief when the driving hydraulic head declines. This process can occur in soils with structured porosity and is typically faster than diffuse matrix flow, contributing to flashier hydrological responses.

Occurrence and significance: Snabbavrinningen can influence the timing and magnitude of runoff in both urban and rural catchments, especially where soils possess rapid drainage routes or where drainage networks channel water quickly. It interacts with land use, soil structure, surface sealing, and initial moisture conditions to shape rainfall–discharge relationships.

Measurement and modeling: Researchers characterize snabbavrinningen using high-resolution rainfall and discharge data, soil moisture observations, and tracer experiments. Hydrological models may incorporate unsaturated flow with preferential pathways and drainage networks to reproduce short time constants and peak flows.

Implications and applications: Understanding snabbavrinningen supports flood risk assessment, stormwater management, and water quality planning by anticipating rapid discharge and the potential for rapid transport of nutrients or contaminants through the system. It also informs design and land-use planning aimed at mitigating extreme runoff events.

See also: rapid runoff, preferential flow, infiltration, drainage, hydrology.