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Sinkholes: Introduction
Sinkholes are natural phenomena in the landscape that covers the majority of
the Barren River Area. These sinkholes have a variety of characteristics. The
actual openings into subterranean caves may be large or small, and the area that
they drain may encompass a few hundred square feet to many acres (Crawford,
1988). The topography of the land surrounding a sinkhole can be gentle and
gradual slopes or steep and rugged terrain. Each sinkhole has unique
characteristics.
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Figure 10-1. Cross-sectional view of sinkholes.
(Source: N. Crawford, Karst Landscape Analysis: Warren County Comprehensive Plan, 1989) |
The karst landscape associated with sinkholes is formed on carbonic rock (i.e.,
limestone and dolomite) as groundwater dissolves and enlarges subterranean
openings. Openings start as small, hardly noticeable cracks in the rock. The
groundwater seeping through the cracks is mildly acidic, giving it solvent power
(Reeder, 1988). As the openings grow in size, they will reach closer to the
ground surface. When they reach the surface, they open as sinkholes (Figure 10-1).
Sinkholes collect stormwater runoff and serve as injection points where runoff
is transferred into underground aquifers. Like streams and rivers, sinkholes
can flood when heavy rainfall occurs. Also, heavy rainfall or general changes
in the volume of water drained into a sinkhole, perhaps resulting from urban
land development in the area, can contribute to sinkholes collapsing. Sinkhole
flooding and collapse can cause significant, localized property damage.
Property owners, developers, and planners should be educated about and prepared
to address the threats associated with sinkholes.
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