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

Outline Background Objectives Work Accomplished Problems Encountered! Future work

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.

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?

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?

Data Sources  Satellite photos, Topo maps, TXDOT  TNRIS (  Aquifers, Well data  TWDB (  Counties  Texas General Land Office (  Flowlines  NHD (

Building the Base Map

Why Plotting by Coordinates is Better Than Plotting by Hand

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

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

QUESTIONS?