Speleogenesis and Delineation of Megaporosity and Karst Geohazards Through Geologic Cave Mapping and LiDAR Analyses Associated with Infrastructure in Culberson County, Texas
The Gypsum Plain region of the Delaware Basin hosts approximately 1800 km2 of the Castile Formation outcrop. A myriad of karstic developments from closed sinkholes to large multi-kilometer cave systems have been documented within the region. Karst studies on the distribution and speleogenetic evolution within Castile strata began within the last decade with ever increasing data resolution. In this study, a combination of both physical field surveys and analyses of high resolution (~30 cm accuracy) LiDAR data was used to create a theoretical model for karst development across the region. This idealized model considers speleogenetic formation type variations (hypogene and epigene), the density of karstic features based on lithology variations, and the connection between the local hydrostratigraphic setting and the regional hydrogeological framework. Field studies included physical mapping of 20 km2 of the Gypsum Plain from the Castile’s western outcrop to where it dips into the subsurface to the east. These surface surveys involved the recording of all surfically-expressed karstic phenomena and the mapping of all enterable caves so that the speleogenetic evolution could be analyzed. The way in which hypogene and epigene caves are surfically expressed across the region indicates that many of the caves have been affected by either multi-stage epigenetic development or multi-stage hypogenetic development with epigenetic overprinting. Through the use of the methods outlined above, surficial karst manifestations vary across the region, from hypogenetic exposures in the west and epigenetic phreatic / vadose exposures in the east. Additionally, supplementary LiDAR data was used to create digital elevation models (DEM) so that the effectiveness of physical field surveys versus remote sensing techniques could be determined. Previous works in the area by Stafford et al., (2008b) determined that remote sensing preserved only 36% of all karstic features found through physical field surveys. Given today’s advancements in remote sensing accuracy, this study determined that on average LiDAR analysis identifies almost seven times more karstic features than physical surveys over a given area
