Living On Karst

 

Sinkhole Management Protects Property Values

Sinkholes are natural depressions in the landscape caused by solution and subsidence of earth materials.

Sinkholes are common throughout about one-quarter of the U.S. Generally sinkholes can be recognized as circular or oval depressions in cultivated fields that may or may not pond standing water after rain events. Sinkholes can also have open bottoms, swallowing entire creeks, springs, or streams, which disappear underground. Both circumstances have one thing in common: caves and/or broken, weathered limestone bedrock near the soil surface. Over thousands of years, flowing groundwater gradually dissolved channels through the limestone. This process created underground caverns of various sizes which can not always support the weight of overlying soil and rock. A sinkhole is created when the surface materials collapse or are dissolved into the underground cavern or cave stream.

  • Surface water or irrigation runoff can wash soil sediment, fertilizers, animal waste, bacteria, and agricultural chemicals into the groundwater below. In sinkholes with open or rocky bottoms, this bypasses the natural filtration and biochemical breakdown processes that occur as water percolates through the soil.

Management Methods

  • If you have sinkholes or caves on your property, help prevent excessive runoff from
    entering groundwater by planting a vegetative barrier and/or fencing around the sinkhole.
  • Avoid structures that divert water naturally flowing into sinkholes. Soil-lined diversion ditches often collapse when storm water erodes through to caves and underground cavities.
  • The size and shape of the vegetated zone needed will depend on the slope of the land and the distance from the disturbed area. A 100-foot-wide grass filter strip is ideal; a 50-foot strip is still helpful; and grass strips even as narrow as 13 feet can trap enough sediment to be effective. Filter strips will remove sediment only from shallow, sheet-type flows; they are less effective in deeper, rapidly flowing water, such as in gullies or ravines.
  • Leave a wide natural buffer of trees and under story vegetation around sinkholes and caves when clearing land, harvesting timber, or disturbing ground in the drainage area.
  • Never dump trash, dead animals, or debris into sinkholes. This is illegal in most areas because it can directly and rapidly funnel leachate to springs and wells.
  • Immediately after disturbing any soil, lightly fertilize, seed, and mulch the area to control erosion. A geotextile may be needed on very steep slopes. Water the area frequently until grass seed germinates. To protect embankments and channels until grass is established, build secure silt fences out of mesh plastic, anchored to the soil, and staked to hay bales.

 

 

©  Copyright 1997, Cave Conservancy of the Virginias

Special Thanks To The West Virginia Cave Conservancy

Rockcastle Karst Conservancy