Living on Karst
A Reference Guide for Landowners in Limestone Regions
Produced by the Cave Conservancy of the Virginias, June 1997
Why Be Concerned About Erosion?
Erosion occurs when rain or flowing water dislodges and transports soil particles, organic matter, and plant nutrients. Erosion carries away soil resources, reduces soil fertility, and produces thousands of tons of sediment that degrade water quality. Soil and sediment may convey pesticides, harmful bacteria, toxins, and nutrients into surface waters and groundwater. Flooding, habitat destruction, and subsidence increase when eroded soil and debris clog creeks, caves, sinking streams, springs, sinkholes, and drainage ways. To reduce erosion and sedimentation, karst features must be identified and receive special protection from erosion impacts.
Signs of Erosion, Sedimentation and Subsidence include:
- Bare soil and cracked earth in and around sinkholes, roads, and building foundations.
- Exposed roots of trees and vegetation
- Gullies carved into banks, slopes, and ditches
- Silt buildup, fresh mud deposits, and muddy water
- Widening and subsidence of stream channels and drainage ways
- Undercut stream banks and fallen trees along drainage ways
Keep Erosion and Sediment Under Control.
Proper land management practices hold soil and nutrients in place and keep sediment, nutrients, and pesticides out of watercourses. Specific best management practices include:
- Conservation and Contour Tillage: Any farming or planting method that utilizes the most level lay of the land and keeps plant residue on the soil surface during critical erosion periods.
- Construction Planning: Any building project that disturbs the soil can create an erosion and sediment problem. In cooperation with your county Erosion and Sediment Control Administrator, proper planning and design can prevent or minimize erosion, sedimentation, flooding, and subsidence in karstlands. Stay away from active karst features such as sinking streams, sinkholes, and lands on top of caves.
- Critical Area Planting: As soon as possible, reseed disturbed areas with temporary and/or native vegetation. Plant rigorous cuttings on bare, undercut, and eroding areas around sinkholes, springs, stream banks, and drainage ways. Maintain vegetated filter strips or grassed waterways down slope of agricultural or construction operations to slow and disperse water evenly over a large area, and to allow the natural removal of sediment, organic matter, and other pollutants carried in the runoff.
- Proper Drainage: Avoid rerouting waterways and drainage patterns in karst. Altering surface flows into sinkholes can cause erosion in the subsurface which results in sudden land collapse or subsidence. Ditches should be lined in areas near caves. Use silt fences to protect karst features and water resources from erosion and sedimentation until vegetation is established.
- Temporary Structures: Protect adjacent property and sensitive springs or streams by constructing silt fences across ditches and drainage ways. These must be inspected frequently and cleaned out after each rain event.
- Silt Fence: A temporary sediment barrier consisting of a synthetic filter fabric stretched across and attached to supporting posts and entrenched.