Evaluation of Groundwater Quality in Paleozoic Aquifers Using GIS Techniques, Central Texas

<p>Lab analyses of groundwater chemistry from monitoring wells completed in the Paleozoic Aquifers surrounding the Llano Uplift of Central Texas has been recorded and made available to the public through the Texas Water Development Board (TWDB). This study evaluated the results of these data dating back to the 1940s to determine changes over time, the dynamics of the hydrologic system, and the locations where hydraulic connectivity is most probable. The initial results established two distinct hydrologic systems that required the separation of the northern from the southern region. The northern sub-region (NSR) contains the largest expanse of continuity of both aquifers, while the southern sub-region (SSR) has experienced extensive compartmentalization of the aquifers due to numerous northeast-southwest trending normal faults. Potentiometric surface maps determined the direction of groundwater flow and specific monitoring wells along flowpaths for analyses. Chemical distribution maps processed by ArcGIS 10.2 provided an aerial view of major constituents during each timeline. This information coupled with the depth vs. concentration graphs has developed a three dimensional representation of the distribution of major constituents in the Paleozoic Aquifers. The majority of samples are dominated by Ca-HCO3 type waters with some locations down gradient evolving into Na-K-HCO3 type in the northern sub-region (NSR) and Ca-SO4 type in the southern sub-region (SSR). The implementation of GIS techniques provides the ability to interpret large quantities of data for broad-scale and local patterns that would be problematic when examining using point-to-point evaluations. </p>

Name thesis:degree_name

Master of Science - Geology

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Geology

Year dc:date.available

2016

Author dc:creator

• Harris, Garrett R

Contributors dc:contributor

• Dr. Kevin Stafford Professor Department of Geology
• Dr. Wesley Brown Chair Department of Geology
• Dr. Matthew McBroom Assistant Chair College of Forestry

• Hydraulic Connectivity
• Nested Pairs
• Piper Diagrams
• Compartmentalization
• Groundwater
• Aquifer
• Earth Sciences
• Geochemistry
• Geology
• Hydrology

Repository record dc:identifier

https://scholarworks.sfasu.edu/etds/45

OAI identifier oai:identifier

oai:scholarworks.sfasu.edu:etds-1037