new concepts for groundwater modeling in the floridan aquifer
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Hazlett-Kincaid, Inc.
New Concepts for Groundwater Modelingin the Floridan Aquifer
Todd R. Kincaid, Ph.D.Timothy J. Hazlett, Ph.D.
Hazlett-Kincaid, Inc.www.hazlett-kincaid.com
Global Underwater Explorerswww.gue.com
Hazlett-Kincaid, Inc.
Problem Overview
• Degrading groundwater quality & increased demand
• Awareness
• Incorporating caves into predictive models & management strategies
- Photo by Wes Skiles
Hazlett-Kincaid, Inc.
Facts from the Field
• 27 (>1/3) of the 78 largestsprings in North America discharge from the Floridan Aquifer
• Average dischargefrom those springs> 6.5 billion gpd
• All of those springs discharge from mapped underwater cave systems
Hazlett-Kincaid, Inc.
Permeability (K) Issues
Porous Media Assumptions• Flow through single media• Standard approach• Isotropy (Kx=Ky=Kz)• Radial flow to wells & spring
Fractured Rock & Karst• Flow through 2 or 3 media• Anisotropic (Kx=Ky=Kz)• Flow trough fractures or conduits
Hazlett-Kincaid, Inc.
Permeability in the Floridan Aquifer
Modified Double Porosity Model • High matrix permeability• Large and extensive dissolved conduits• Fractures of lesser importance
Hazlett-Kincaid, Inc.
Cave Types in the Floridan AquiferFlow-dominated
Storage-dominated
• discharge to springs• fast through-flow• e.g. - Wakulla, Ichetucknee, Manatee, Blue Springs, etc.
• no surface discharge• slow through-flow• e.g. - Dipolder, Blue Grotto Gunpowder, 40 Fathom Grotto, etc.
Hazlett-Kincaid, Inc.
Woodville Karst Plain
• dual porosity system (matrix & conduit)• rapid recharge through sinkholes• discharge at springs
Hazlett-Kincaid, Inc.
Hydraulic Cave Development Model
(Huntoon, 1984)
• cave orientation function of flow system not geology• caves aligned w/ gradient• caves will be smaller and more branched up-gradient• feedback loop between gradient & conduits
• Caves can be included in groundwater flow models provided the model can handle permeability contrast
Hazlett-Kincaid, Inc.
Potentials for Groundwater Modeling
Improved Predictions• groundwater flow patterns & velocities• spring catchment areas• contaminant transport times
Probable Cave Locations• iterative modeling
Understanding Cave Development
Hazlett-Kincaid, Inc.
Preliminary Modeling
Wakulla Spring Sub-basinAdvanced Technology• finite-element grid• embraces anisotropy• high permeability contrasts• calibrate to spring discharge
Hazlett-Kincaid, Inc.
Preliminary Modeling – Hydraulic Head
Hazlett-Kincaid, Inc.
Preliminary Modeling - Velocity
Hazlett-Kincaid, Inc.
Preliminary Simulation – Particle Tracks
Wakulla Spring
Standard Methods / Modeling Our Modeling Including Cave
Wakulla Spring
Hazlett-Kincaid, Inc.
Work in Progress
- Photo by Wes Skiles
Applied • groundwater model of the Wakulla Spring sub-basin• adaptation to other spring basins
Theoretical • collaboration with FSU• developing new modeling code
Hazlett-Kincaid, Inc.
Concluding RemarksCritical Issue
• Aquifer Protection
– Contamination
– Over use
Critical Areas
• Suwannee River Basin
– Degrading water quality
• North Florida
– Aquifer management
Need
• Improved predictive capabilities - modeling that includes conduit flow
www.gue.comwww.hazlett-kincaid.com
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