IMPROVED KARST SINKHOLE MAPPING IN KENTUCKY USING LIDAR TECHNIQUES: A PILOT STUDY IN FLOYDS FORK WATERSHED

Abstract: The existing sinkhole database for Kentucky is based on low-resolution topographic maps created more than fifty years ago. LiDAR (Light Detection and Ranging) is a relatively recent technique that rapidly and accurately measures features on earth's surface in high-resolution. To test the feasibility of using LiDAR to map sinkholes in Kentucky, we have developed a method of processing LiDAR data to identify sinkholes and tested the method in portions of the Floyds Fork watershed in central Kentucky. The method consisted of four steps, creating a high-resolution digital elevation model (DEM) from LiDAR data, extracting surface depression features from the DEM, inspecting the depression features for probable sinkholes, and verifying the probable sinkholes in the field. A total of 1,683 probable sinkholes were identified in the study area, compared to 383 previously mapped for the same area. We field-checked 121 randomly-selected probable sinkholes and confirmed that 106 of them were karst sinkholes. This method increased the number of sinkholes by a factor of four with a success rate between 80% and 93% for the study area, demonstrating that the LiDAR sinkhole-mapping method is reliable and efficient. This method identified approximately 55% of the previously mapped sinkholes, and approximately 98% of the missed sinkholes appeared to be filled or covered for urban development and agriculture purposes. The next step is to extend this method to provide high-resolution sinkhole maps for other karst areas in Kentucky where LiDAR data become available