Location

Stephen F Austin State University, Baker Pattillo Student Center, Student Center Theatre and Twilight Ballroom

Start Date

17-4-2018 4:00 PM

End Date

17-4-2017 7:30 PM

Description

The Fort Hood Military Installation is a karst landscape characterized by Cretaceous-age limestone plateaus and canyons in Bell and Coryell counties, Texas. The area is located in the Lampasas Cut Plain region of the Edwards Plateau and is stratigraphically defined by exposures of the Fredericksburg Group, namely the Comanche Peak and Edwards carbonates. The topography is dominated by plateaued draining divides capped by the resistant Edwards limestone and bordered by steep scarps exposing alternating layers of the Comanche Peak and Edwards units. This interfingering relationship has created a variable slope along the edges of the plateaus, defined by lithology.

The study area is located in the northeastern portion of the installation, and provides numerous outcrops of the Fredericksburg Group carbonates for terrain analyses. Traditional methods such as field surveying can yield accurate results; however, they are limited by time and physical constraints. Airborne Light Detection and Ranging (LiDAR) provides an alternative for high-density and high-accuracy three-dimensional terrain point data collection. For the purposes of this study, a 1m Digital Elevation Model (DEM) derived from LiDAR captured in March of 2009 was used as a base map to determine the slope of selected outcrops, and slope analysis derived from the DEM was used to create a profile graph of these outcrops. These data were used to create a slope profile to predict outcrop patterns for the Comanche Peak and Edwards limestones. Field verification and refinement of this model was conducted in order to correct for anthropogenic modifications of slope by Army training activities and road building. Steeper slopes and recessed outcrops associated with the interfingering of the Comanche Peak and Edwards carbonates were not easily resolved by the digital elevation model with regard to slope and outcrop pattern, while gentler slopes were portrayed more accurately with regard to slope but the resolution associated with outcrop patterns were less clear.

Although the increasing capabilities of GIS (Geographic Information Systems) and accuracy of geographically referenced data has provided the basis for detailed terrain analysis and modeling, research on terrain-related surface features is highly dependent on terrain data collection and the generation of digital models. Although LiDAR analysis can be a powerful tool, filter mechanisms must be employed to remove major natural and anthropogenic terrain modifications resulting from military training exercises, road building and maintenance, and the natural influence of water bodies throughout the study area.

Comments

Faculty Sponsors: Mindy Faulkner (Department of Geology) and Matthew A. Beauregard (Department of Mathematics and Statistics)

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Apr 17th, 4:00 PM Apr 17th, 7:30 PM

Predicting Stratigraphic Outcrops Using a LiDAR Digital Elevation Model in a Karst Landscape, Fort Hood Military Installation, Texas

Stephen F Austin State University, Baker Pattillo Student Center, Student Center Theatre and Twilight Ballroom

The Fort Hood Military Installation is a karst landscape characterized by Cretaceous-age limestone plateaus and canyons in Bell and Coryell counties, Texas. The area is located in the Lampasas Cut Plain region of the Edwards Plateau and is stratigraphically defined by exposures of the Fredericksburg Group, namely the Comanche Peak and Edwards carbonates. The topography is dominated by plateaued draining divides capped by the resistant Edwards limestone and bordered by steep scarps exposing alternating layers of the Comanche Peak and Edwards units. This interfingering relationship has created a variable slope along the edges of the plateaus, defined by lithology.

The study area is located in the northeastern portion of the installation, and provides numerous outcrops of the Fredericksburg Group carbonates for terrain analyses. Traditional methods such as field surveying can yield accurate results; however, they are limited by time and physical constraints. Airborne Light Detection and Ranging (LiDAR) provides an alternative for high-density and high-accuracy three-dimensional terrain point data collection. For the purposes of this study, a 1m Digital Elevation Model (DEM) derived from LiDAR captured in March of 2009 was used as a base map to determine the slope of selected outcrops, and slope analysis derived from the DEM was used to create a profile graph of these outcrops. These data were used to create a slope profile to predict outcrop patterns for the Comanche Peak and Edwards limestones. Field verification and refinement of this model was conducted in order to correct for anthropogenic modifications of slope by Army training activities and road building. Steeper slopes and recessed outcrops associated with the interfingering of the Comanche Peak and Edwards carbonates were not easily resolved by the digital elevation model with regard to slope and outcrop pattern, while gentler slopes were portrayed more accurately with regard to slope but the resolution associated with outcrop patterns were less clear.

Although the increasing capabilities of GIS (Geographic Information Systems) and accuracy of geographically referenced data has provided the basis for detailed terrain analysis and modeling, research on terrain-related surface features is highly dependent on terrain data collection and the generation of digital models. Although LiDAR analysis can be a powerful tool, filter mechanisms must be employed to remove major natural and anthropogenic terrain modifications resulting from military training exercises, road building and maintenance, and the natural influence of water bodies throughout the study area.