KARST DEPRESSION CHARACTERIZATION USING LIDAR AND FIELD TRAVERSES: FORT HOOD MILITARY INSTALLATION, TEXAS

The Fort Hood Military Installation is a karst landscape characterized by outcrops of Lower Cretaceous limestones and dolostones from the Fredericksburg Group. The study area includes the Shell Mountain and Royalty Ridge provinces in western Fort Hood, covering approximately 40 km² and bounded by the western border of the installation and the central “live-fire” range. It has been significantly altered for military training exercises that encompass heavy vehicle maneuvers and simulated combat. Recent spatial interpolation of karst features using .5-meter LiDAR captured in March 2015 delineated and classified a depression database using geoanalytical methods. Initial filtering mechanisms were employed to remove anthropogenic depression features resulting from terrain modifications by military use, road building and maintenance, and the natural influence of water bodies in the study area.

The focus of this study was the refinement of the depression database by employing additional filtering mechanisms to existing buffers to insure that this terrain is adequately characterized with respect to natural karst and anthropogenic features associated with military activity. Field traverses (n=33) and random point checks (n=100) were conducted to verify karst features remaining in the depression databases. Results show that filtering mechanisms based on lithology and proximity to natural water bodies accurately characterized karst depressions. Filtering mechanisms associated with minor roads were least accurate, mostly due to the ephemeral nature of road building in military training areas. Minor roads and bypass features created and utilized by wheeled and tracked machinery as a part of military traverses in the training areas caused this filtering mechanism to report higher error associated with the characterization of anthropogenic and natural karst depressions.