Digital Mapping Techniques '99 -- Workshop Proceedings
U.S. Geological Survey Open-File Report 99-386

The Integration of Sinkhole Data and Geographic Information Systems: An Application Using ArcView 3.1

By William E. Kochanov

Pennsylvania Geological Survey
P.O Box 8453
Harrisburg, PA 17105-8453
Telephone: (717) 783-7253
Fax: (717) 783-7267

The Pennsylvania Geological Survey initiated the sinkhole inventory project in 1985 to systematically map karst features on a county-wide basis. Each hard-copy county report includes a brief explanatory text and copies of 7.5 minute quadrangle maps (scale 1:24,000) that show the locations of sinkholes, surface depressions, surface mines, cave entrances, and carbonate bedrock geology. Fourteen counties have been surveyed in detail and six others have had a less detailed, reconnaissance survey completed.

The PC-based GIS software ArcView v. 3.1 is being used to analyze the data. Themes are created to include: a digital raster graphics (DRG) 7.5 minute topographic base map, a digital geologic base, geo-referenced karst data, and a box-style grid with grid cell spacings set at 500 feet to cover the 7.5 minute base map. Using sum and join functions, each unit cell containing karst point data is identified, the number of features contained within the unit cell is counted, and a color that corresponds to a particular range of numbers is assigned to that unit cell. The end product is a color-coded map that shows the density of karst surface features over a given area. The distribution of these features becomes visually apparent by showing high-density (bad) areas and low-density (good) areas. By using the identify function, additional information about a particular point can be obtained.

This customized data can be utilized for a variety of projects ranging from permit applications to land-use planning to spatial analysis.

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