1. Travertine Deposits as Records of Urbanization Impacts, Austin, TX Laura M. DeMott December 1, 2005

2. Outline Background Objectives Work Accomplished Problems Encountered! Future work

3. Background What is a Travertine?  Travertines are surface deposits of calcite (CaCO 3 )  They precipitate directly from supersaturated spring waters via degassing of CO 2  The calcite structure can record the water chemistry at the time of travertine precipitation.

4. Background  Urbanization causes many changes to water chemistry, amount, etc.  Urbanization in Austin has increased dramatically over the past 40 years with no record of what the water was like beforehand  Can travertine geochemistry show these effects?

5. Objectives  Create base map showing sample sites and urban land use  Delineate the drainage areas for each site as a proxy for recharge areas  Contour the water table?

6. Data Sources  Satellite photos, Topo maps, TXDOT  TNRIS (http://www.tnris.state.tx.us/digital.htm)  Aquifers, Well data  TWDB (http://www.twdb.state.tx.us/mapping/gisdata.asp)  Counties  Texas General Land Office (http://www.glo.state.tx.us/gisdata/gisdata.html)  Flowlines  NHD (http://nhd.usgs.gov/data.html)

7. Building the Base Map

10. Why Plotting by Coordinates is Better Than Plotting by Hand

13. Drainage Areas  DEM Problems!  Stupid geology computers won’t let me download USGS seamless DEMs  Other DEMs won’t work!  Only working DEM of poor quality

14. Future Work  Find a DEM that works!  Delineate the watersheds for each of my sites  Figure out how to contour the potentiometric surface based on TWDB well data  Show the areas contributing groundwater to the springs

15. QUESTIONS?