Zapadanie

Zapadanie (Polish for subsidence) is a geotechnical term referring to the gradual or sudden sinking of the ground surface or subsurface structures relative to a reference level. In Polish usage, it covers subsidence caused by natural processes as well as human activities, and it is a common concern in engineering, urban planning, and geoscience.

Natural causes include karst dissolution, where soluble rock such as limestone dissolves to create voids that may collapse, tectonic subsidence driven by crustal movements, and long-term consolidation of sediments under load. Anthropogenic causes include extraction of groundwater, oil or gas, and minerals; underground mining; rapid drainage of peatlands; and construction that alters load distribution or drainage patterns. Subsurface voids created by mining or groundwater withdrawal may lead to progressive settlement or sudden collapse as support is lost.

Surface effects range from minor unevenness to visible cracks in walls, chimneys, and roads, tilting of buildings, and damage to infrastructure such as pipelines and railways. Hydrological changes can occur due to altered drainage patterns. Hazards include structural damage, increased flood risk in subsiding zones, and, in the case of karst, sudden sinkholes.

Monitoring methods include geodetic leveling, global navigation satellite system measurements, interferometric synthetic aperture radar (InSAR), and surface surveys. Mitigation approaches focus on land-use planning, controlled extraction, backfilling and grouting of voids, pressure grouting, and, where feasible, post-subsidence stabilization or rebuilding.

See also: subsidence, sinkhole, ground settlement, geotechnical engineering.