Karst Potential Help File

Karst Potential Classification

The karst potential map shows the tendency for geologic units to develop or have karst features such as sinkholes, springs, caves, or other solution features. The classification is based on lithology. The lithologic characteristics used are percentage of CaCO₃ in the carbonate portion of the unit, grain size, bedding thickness, and insoluble components. Insoluble components may occur as a mineral grains within the limestone lithology or as interbeds of noncarbonate rock. These criteria were evaluated for all rock units and combined rock units that appear on the map, and resulted in about 50 distinct rankings. These rankings were reduced to three to five simplified classes by analysis of their frequency of distribution and the scale of the map data.

The 1:500,000 karst potential map layer contains polygons which represent the geologic formations from the 1:500,000-scale 1988 Geologic Map of Kentucky, which was compiled by Martin C. Noger (KGS) from the 1981 Geologic Map of Kentucky (Scale 1:250,000) by McDowell and others (USGS). Polygons are styled by karst potential which was published in "Karst Occurrence in Kentucky", Paylor, R.J. and Currens, J.C., KGS Map and Chart Series 12, Issue 33.

The 1:500:000 karst potential layer displays three classes at all scales:
	INTENSE Areas underlain by bedrock with high potential for karst development. May exhibit mature karst, including caves, sinkholes, and springs where they crop out.
	PRONE Areas underlain by bedrock with moderate potential for karst development. Development of karst features in this category is variable and dependent on site-specific conditions. Occurrence of caves may be influenced by physiographic setting, unit thickness, and lithology.
	NONKARST Areas underlain by bedrock with limited or no potential for karst development. Karst features rare or absent.

What happened to the 1:24,000 karst potential data? We have recently been working to update the karst information on the KGS website and found the data presented on the 1:24,000 karst potential layer needed improvement before being shared and are working to update it to get it back out to the public as soon as we can. Please contact Chuck Taylor (KGS Water Resources Section Head) for any questions.

Two different sinkholes layers are displayed in this layout:
	Statewide Sinkhole Outlines These data represent digital GIS sinkhole coverage for all of Kentucky. The highest elevation, closed, topographic contour of each mapped sinkhole was digitized as a GIS polygon. The second highest elevation contour was also digitized where very large, shallow, karst valleys were so expansive that the area covered by the polygon obscured patterns in sinkhole distribution. These karst valleys are mostly confined to the Western Pennyroyal. The spacing of contour intervals on the topographic maps of the state vary in from 40 foot to 10 foot. No attempt was made to use a constant elevation, standardize the outline to a uniform contour interval, or record the elevation of the digitized contour. Digitization was done onscreen using digital raster graphic files of the 7.5-minute topographic contours, registered and projected to the Kentucky State Plane coordinate system.
	LiDAR-derived Sinkhole Outlines The sinkhole maps are derived from LiDAR data using ArcGIS 10.1. LiDAR data were used to create digital elevation model (DEMs). Surface depressions were then extracted from the DEMs and visually inspected for sinkholes. Field verification suggests that the accuracy of the identified sinkholes to be real sinkholes is over 85%. The data provided here are provisional and updates will be provided if needed. LiDAR data were provided by the Louisville/Jefferson County Information Consortium (LOJIC) through Kentucky Division of Geographic Information. The LiDAR was flown in August, 2009 and the average point spacing is 1.0 meter. DEMs were created using LAS Class 2 surface with 5 feet resolution. Each sinkhole is presented as a polygon feature and the attribute table contains the following fields: SinkholeID: an 8-digit numerical code, in which the left three digits represent FIPS county code and the remaining five digits are sequential. Latitude: latitude of the centroid of the sinkhole Longitude: longitude of the centroid of the sinkhole Area_sqft: the approximate surficial area of the sinkhole County: County location of the sinkhole Method: the method used for identifying the sinkhole Field Verified: Show if the sinkhole is checked and verified in the field.