Produced by the Cave Conservancy of the Virginias, June 1997
Karst is defined as a landscape with topographic depressions such as sinkholes and caves, caused by underground solution of limestone bedrock. This landscape features underground streams and aquifers which supply the wells and springs that communities use for their drinking water. Karst protection requires an understanding of the watershed and the will to protect the natural resources within it.
Everyone lives in a watershed. Even if a home is not next to a stream, it is in a watershed, and common everyday practices can contribute to the overall pollution entering into that water system.
The hollow nature of karst terrain results in a very high pollution potential. Streams and surface runoff entering sinkholes or caves bypass natural filtration through the soil and provide direct conduits for contaminants in karst terrain. Groundwater can travel quite rapidly through these underground networks - up to several miles a day - and contaminants can be transmitted quickly to wells and springs in the vicinity.
Groundwater is an important source of private and public water supplies. However, everyday activities in the source area can contaminate the groundwater on which so many people depend for everyday use. The source area is the land surface that contributes water to an aquifer. It is very important to protect these source areas from detrimental activities.
A watershed is an area of land from which all water drains into a common water body. Rainfall, spring runoff, and groundwater drain from upland areas to a low point or basin, usually a larger stream, river, lake, or bay.
Water enters a karst watershed through both direct and indirect means. Precipitation in the form of rain and snow, which is usually the greatest during January through May, enters the aquifer directly as surface runoff or indirectly as water seeping through the soil and bedrock. Drainage in karst watersheds tends to be three dimensional; flowing laterally across the surface, as well as vertically underground.
Residents of a watershed can protect groundwater by minimizing land disturbances, soil erosion, heavy runoff of storm water, and pollutants. Groundwater is at a much higher risk where watersheds are characterized by overgrazing, high-density development, agricultural or urban runoff, and mismanaged commercial facilities sites.