Please note: this presentation has not received Director

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Please note this presentation has not received
Directors approval and is subject to revision.
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Geophysical Monitoring of theSouthwest Florida
Coast

• David Fitterman and Maryla Deszcz-Pan
• U.S. Geological Survey
• Crustal Imaging and Characterization Team
• Denver, Colorado

U.S. Department of the Interior U.S. Geological
Survey
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TIME Model Area
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TIME Model Data Needs

• Hydrologic/geologic boundaries
• Boundary conditions (head/stage/flow)
• Permeability information
• Water quality ( Cl, SC)
• Cell size 500 m x 500 m
• 5000 sq km area

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Meeting Model Data Requirements

• Drill observation well
• Collect core
• Geophysical logging
• Install well
• Pump, collect sample
• Measure SC and Cl
• Interpolate between wells

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Problems of Traditional Approach

• Well coverage is often sparse
• Access may limit installation of additional wells
• Interpolation between wells can give geologically
  inaccurate result

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Where is 250 mg/l interface?
Well data alone gives ambiguous interpretation.
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Geophysically Estimated Cl at 10m
High density airborne data give detailed picture.
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TIME Models

• 5000 sq km
• 500 m x 500 m cells
• Incorporates solute transport

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HelicopterElectromagneticSystem

• Bird mass 200 kg
• Bird length 10 m
• Tow cable 30 m
• Bird height 30 m

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Helicopter Electromagnetic Bird

• Five TX-RX coil pairs
• Frequency controls depth of investigation

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HEM Data Collection Interpretation
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HEM Survey Areas
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Depth-Slice Map z5 meters
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Depth-Slice Map z10 meters
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Depth-Slice Map z20 meters
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Depth-Slice Map z40 meters
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Resistivity, SC, and Cl
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TIME Simulated Chloride
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Comparison of Simulated Cl and HEM
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Conclusions

• HEM can provide detailed resistivity information
• HEM spatial sampling interval smaller than
  hydrologic model cell size
• Data collection more rapid than drilling
• Borehole information needed for rf gt Cl
• TIME variable-density, ground-water flow model
  using these results