CHARACTERIZATION OF ILLINOIS’ SINKHOLE PLAIN USING AIRBORNE LIDAR DATA AND A NEW ARCGIS-BASED PROGRAM

Illinois’ sinkhole plain occupies parts of three counties in southwestern Illinois and contains over 15,000 cover-collapse sinkholes and numerous caves. The USGS 7.5-minute Waterloo and Renault Quadrangles contain the highest density of sinkholes the majority of which are situated beneath dense woodland and other vegetation. High-density airborne lidar data acquired in early in April, 2012 have made it possible to conduct a detailed first-time inventory of the karst features within these two quads, which is leading to a better understanding of sinkhole morphology and evolution within an intensively karstified landscape. Cover-collapse sinkholes originated along the margins of the groundwater basin as losing stream channels, evolved into compound sinkholes, and finally eroded into simple circular sinkholes. Using lidar bare earth data as input, a custom program tool for use in ArcGIS has been developed to detect and delineate sinkholes and related karst features. Preliminary results using this new approach will be discussed.