1. Chemical Hydrogeology of the Hill Country, Texas
Megan Andring /20/2008

2. Study Area

3. Problem Definition Zone of high SO4 in well water
Why is SO4 distributed linearly?
How can GIS be used to analyze this problem?
Travis
Kendall
Kerr
Blanco
Comal
Hays
Gillespie
Medina
Bandera
Bexar

4. Data & Approach Use TX well data Analyze trends in chemistry
Look for spatial trends

5. Central Texas Geology Mostly Cretaceous limestone and evaporites
Gypsum: CaSO4
Calcite: CaCO3
Halite: NaCl

6. Methods: Well Chemistry Data

7. Methods: Well Chemistry Data

8. Methods: Well Data
Join chemical data for wells to spatial data

9. Results: Trends in Chemistry

10. Results: Trends in Chemistry

11. Results: Trends in Chemistry
Separate wells by geologic unit

12. Results: Interpolation

13. Results: Spatial Trends
Compare SO4 distribution with elevation

14. Results: Spatial Trends
Compare SO4 distribution with elevation

15. Results: Spatial Trends
Compare SO4 distribution with elevation

16. Summary of Findings SO4 concentrated in Glen Rose & related formations
Highest SO4 concentrations found on interfluves

17. Future Work
Compare locations of known gypsum layers in Glen Rose Fmn. with well data
Delineate watersheds using ArcHydro & compare with SO4 distribution

18. Data Sources & Acknowledgements
Texas Water Development Board
Texas Commission on Environmental Quality
Texas Natural Resources Information System
Ron Fieseler, Groundwater District Manager, Blanco County
Dr. Phil Bennett, Jackson School of Geosciences