The removal of groundwater to reduce flow-rate or diminish pressure. Methods used depend on the permeability of the ground, the proximity of hydrogeologic boundaries (see hydraulic boundary), the storage coefficient of the soil, pressure, and hydraulic gradient. Methods used include abstraction by wells, electro-osmosis, sumps and drains, vertical drains, or exclusion by grouting, compressed air, or freezing techniques. Dewatering is usually undertaken to improve conditions in surface excavations and to help construction work at or near the surface.
Subjects: Ecology and Conservation — Earth Sciences and Geography.