läbivool

Läbivool (throughflow) is the movement of water through the soil profile from the surface toward streams or groundwater. The term describes water that moves through the unsaturated and sometimes saturated zones, often laterally within the upper soil layers (interflow) or vertically toward the groundwater (percolation). Throughflow is driven by gravity, hydraulic gradients, and the soil’s hydraulic conductivity, and it is facilitated by preferential flow paths such as macropores, cracks, and soil pipes. In landscapes with permeable soils or layered substrates, throughflow can involve perched water tables or drainage systems that channel water to the stream network.

Throughflow influences the timing and magnitude of streamflow after rainfall and plays a key role in nutrient and sediment transport from land to water bodies. It is a central component of watershed hydrology, soil moisture dynamics, and many ecological processes in wetlands and riparian zones.

Studying throughflow employs tracer experiments, seepage meters, lysimeters, and hydrological modelling to separate subsurface flow from surface runoff and baseflow. Understanding throughflow supports flood forecasting, water quality assessment, and land-management practices such as drainage design and erosion control.

See also: interflow, percolation, baseflow, runoff, drainage.