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Overgrazing in Europe several centuries ago caused severe erosion of soils in many karst areas, leaving only bare, fissured rock surfaces.
Although most sinkhole collapse is triggered by high discharge of underground streams, lowering of water tables by over pumping in areas underlain by thick soils or weak rocks can induce ground failure and collapse into subsurface voids.
Once a certain conduit size threshold is exceeded, typically around 10-20mm, flow becomes turbulent.
Karst in carbonate rocks is formed by their dissolution by acidic water.
Karst regions are also important scenic attractions and can contribute significantly to the local economy, for example the Tower Karst around Guilin and Mammoth Cave National Park, Kentucky.
The karst system is sensitive to many environmental factors and can form a significant geohazard.
However, they can be influenced by human activities such as land-use modification (e.g.
deforestation), alteration of surface drainage, waste disposal, and opening or blocking of cave entrances, all of which can substantially affect sedimentation, speleothem deposition and groundwater quality over the short term.