Applications of Laser Terrian Mapping in Central Texas for Managing Karst Aquifers and Land Use

This investigation demonstrates the effectiveness of using airborne laser terrain mapping (ALTM) data, also known as lidar data, in combination with QUICKBIRD satellite imagery for mapping applications relevant to managing karst limestone aquifers and land use in Central Texas. Test-case studies conducted within the south Austin, Texas, area (Fig. 1) highlight the utility of lidar data, either alone or in conjunction with other imagery, for mapping karst-related recharge features, areas susceptible to slope failure, terraces of flood-prone streams, and faults in hilly limestone terrain.

The south Austin urban and suburban area serves as an ideal study location to assess the applicability of ALTM for geological mapping. This area encompasses both developed and undeveloped regions, experiencing rapid urban expansion, and its geology significantly influences water resource management, land use planning, and construction practices (Woodruff, 1975; Garner and Young, 1976; Woodruff and Collins, 2001). Geological maps and understanding of geological features such as karst formations, faults, and the physical properties of lithological units and associated soils are crucial for addressing water resource management, land use planning, and construction challenges. For instance, the Cretaceous bedrock in the region includes the extensive Edwards limestone aquifer and its recharge zone. The identification of recharge features like dolines is essential for comprehending groundwater recharge, flow dynamics, quality, and for permitting various construction projects.

Moreover, Austin's geological composition comprises a stratigraphic interval approximately 140 feet thick, consisting of Cretaceous Del Rio clay, Buda limestone, and Eagle Ford clay, shale, marl, and bentonite. The clay-rich Del Rio and Eagle Ford strata, along with their soils, exhibit relatively low slope stability and foundation strength. Additionally, the clays possess expansive characteristics, leading to swelling when moist and contracting when dry. Mapping of areas with higher slopes prone to slope failure within these strata is crucial for construction project planning and roadway maintenance.