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Travertine Deposits as Records of Urbanization Impacts, Austin, TX

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 )

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Travertine Deposits as Records of Urbanization Impacts, Austin, TX

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  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 (CaCO3) • They precipitate directly from supersaturated spring waters via degassing of CO2 • 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

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

  9. 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

  10. 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

  11. QUESTIONS?

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