Geologic And Geochemical Characterization Of Cross-Communication Potential Within The Northern Edwards Aquifer System, Texas, Ingrid J. Eckhoff

Electronic Theses and Dissertations

The Edwards Aquifer is a large, complex groundwater system located throughout Central Texas in association with the Balcones Fault Zone. The San Antonio and Barton Spring segments of the Edwards Aquifer have been extensively studied in the past because they provide groundwater resources to the largely urbanized areas of San Antonio and Austin, respectively, and smaller communities along the Interstate 35 corridor. Previous research has been conducted on these southern and central portions of the Edwards Aquifer system, which have characterized the structural, hydrogeological and geochemical variations within the highly karsted region. However, the Northern Segment of the Edwards Aquifer …

Temporal Co2 Variations And The Influence Of Bat Colonies In Speleogenesis: Continuous Co2 Monitoring In War Eagle Cavern, Arkansas, Ginny Sue Holcomb

Graduate Theses and Dissertations

Dissolved concentrations of CO2 in a karst aquifer are a major control on calcite dissolutional processes, as CO2 combines chemically with water to form carbonic acid. As increasing amounts of CO2 are added to the system, greater resultant water aggressivity generates greater rates of dissolution. Spatial and temporal variations in carbon flux through the system may occur over a range of time scales, and high-resolution data collection is needed to truly understand and characterize such variability. Continuous CO2 monitoring in War Eagle Cavern, Arkansas, will suggest a number of influential parameters with varying degrees of importance throughout an annual cycle. …

Geochemical Attributes Of Hydraulically Active Fractures And Their Influence On Groundwater Quality, Amy L. Hudson

Doctoral Dissertations

This study utilized discrete interval diffusion sampling of a fractured bedrock well completed in schist to investigate if a natural weathering signal can be used to identify hydraulically active fractures. The open borehole well MFS-1, is the focus of the study, which is in close proximity to the recharge zone making it ideal for testing the hypotheses of this study. The hydraulically active fractures of Well MFS-1 were identified, and the dominant mixing force of the water column of the well was determined to be thermal convection in the upper portion of the well and upward gradients. The isotopic data …

Determining Groundwater Sources And Ages Via Isotope Geochemistry In Big Sky, Montana, Thomson Connie

Graduate Theses & Non-Theses

The Big Sky ski resort area in southwestern Montana is experiencing exponential growth in both development and population. Concerns have arisen over the quantity of good-quality groundwater in the region, and whether there is a large enough reserve to support the growing demand. In light of already-documented water-level decreases, and domestic wells needing to be deepened or replaced, the Montana Department of Natural Resources and Conservation (DNRC) enlisted the Montana Bureau of Mines and Geology's Ground Water Investigation Program to perform an assessment of groundwater availability and quality in the region, and define groundwater supply sources.

The geology in the …

An Investigation Of Hydrogeologic, Stratigraphic, And Structural Controls On Acer Grandidentatum Communities In A Karst Landscape, Owl Mountain Province, Fort Hood Military Installation, Texas, Melinda S. Faulkner

Electronic Theses and Dissertations

The Owl Mountain Province is located within the Fort Hood Military Installation, an approximately 880 km2 installation established in the 1940s in Bell and Coryell counties, Texas, which has undergone extensive land use changes associated with military training, maintaining much of the vegetation in early succession. This study investigates thelithologic, stratigraphic, and structural controls on the hydrologic, hydrogeologic, and geomorphologic evolution of the Owl Mountain Province as expressed by mesic vegetation communities, including Pleistocene relicts Acer grandidentatum, within karst terrains. These systems exhibit complexly overprinted speleogenetic evolutions within a dynamic groundwater regime resulting from regional climate shifts throughout the …

Speleogenesis Of Critchfield Bat Caves And Associated Hydrogeology Of The Northern Edwards Aquifer, Williamson County, Texas, Ashley N. Landers

Electronic Theses and Dissertations

Karst development in the Edwards Aquifer has been significantly studied in the San Antonio and Barton Spring Segments; however, karst development remains poorly studied in the Northern Segment. Detailed characterization of the Northern Segment is vital for future water conservation because of increasing urban sprawl along the Interstate 35 corridor. The Northern Segment of the Edwards Aquifer consists of Lower Cretaceous strata of the Comanche Peak, Edwards, and Georgetown formations. The stratigraphy is dominated by Edwards Limestone as it is the only formation that crops out in the study area.

Karst, stratigraphic, GIS, and geochemical studies were conducted to evaluate …

Modeling The Influence Of The Heterogeneous Substrate On The Transport Of The Jet Fuel Solute Plume, Kirtland Air Force Base, Albuquerque, New Mexico, Hannah Sarah Gatz-Miller

Earth and Planetary Sciences ETDs

A subsurface model was developed to characterize the influence of heterogeneity on solute phase plume migration of the Jet Fuel spill of Kirtland Air Force Base. Core –logs from KAFB boreholes were compiled, and lithology was interpolated across the study area using transition probability geostatistics (T-PROGS). High conductivity materials in the travel path resulted in a faster than average breakthrough time while, if low conductivity materials were placed in the travel path, particles were either forced to divert around the low K material, which added time and changed the direction of travel, or were forced by the hydraulic gradient to …

Lnfluence Of Persulfate On Solidification/Stabilization Characteristics Of Iss Treatment, Jeffrey M. Hudson

Masters Theses

Two environmental remediation technologies that lend themselves well to being combined in a single application are In Situ Chemical Oxidation (ISCO) using activated persulfate (PS), and In Situ Stabilization (ISS). Persulfate can be activated by increasing the pH to 10.5 and/or increasing temperatures to 30ºC. Many common ISS amendments increase temperature to 30°C and/or pH to 10.5 when in contact with soil water. Laboratory experiments were conducted with various soils to determine the ability of eight ISS amendments to activate persulfate. All eight ISS amendments activated persulfate. This work also showed that the relative contribution of heat vs. alkaline activation …

Sources Of Water And Solutes To The Salar De Atacama, Chile: A Coupled Hydrologic, Geochemical, And Groundwater Modeling Study, Lilly G. Corenthal

Masters Theses

Focused groundwater discharge in endorheic basins provides opportunities to investigate mechanisms for closing hydrologic budgets in arid regions. The Salar de Atacama (SdA), a closed basin in northern Chile, has accumulated over 1800 km³ of halite and a lithium-rich brine since the late Miocene primarily through evapotranspiration of groundwater. The hydrologic balance of SdA and sources of water and solutes required to explain this deposit are not well constrained. An adapted chloride mass balance method drawing on a database of over 200 water sample sites is applied to a remotely-sensed precipitation dataset to estimate spatially-distributed modern groundwater recharge. Comparing …