Land subsidence is largely caused by over-extraction of groundwater supplies for human consumption and use. Soil compaction in response to excessive pumping of aquifer systems results in permanent subsidence and ground failures in many places around the globe. The compaction of porous soil also has consequences for total storage capacity of an aquifer system, wherein it never regains its pre-extracted ability to store water supplies. Drainage of organic soils, underground mining practices, and thawing permafrost also cause land subsidence.