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Groundwater Continued

Learn about the groundwater systems in Florida, including confined and unconfined aquifers, their classification, and the geologic materials involved. Discover the importance of these aquifers and their vulnerability to pollution.

ryansaunders
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Groundwater Continued

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  1. Groundwater Continued

  2. Aquifers Consolidated Unconsolidated Confined Unconfined

  3. Unconsolidated Aquifer Consolidated Aquifer Basic Aquifer Classification Unconsolidated or Consolidated Unconsolidated: granular sand or gravel Consolidated: sandstone, limestone, granite Can be low-yield or high-yield Granite, sandstone Limestone, sand/gravel

  4. Unconfined Aquifer Water High permeability Low Conductivity Geologic or Soil material Conductivity: the ease with which water moves through material

  5. Confined Aquifer An inclined, water-bearing formation located below an impermeable layer of clay, rock, or shale. Flow High pressure

  6. Confined and Unconfined Flow aquitard High pressure

  7. Florida’s Aquifers

  8. Georgia Channel Suwannee Current Florida’s Aquifers • Florida has both confined and unconfined aquifers • Florida exists on a raised platform • The Florida platform was dominated by carbonate deposition • from the Jurassic (-200 my) to the Miocene (-25 my). • 4. During the Miocene, clayey sediments blanketed the platform. • 5. These sediments form a confining unit for Florida’s main aquifer • 6. The major aquifer is a consolidated, carbonate confined aquifer. • 7. Unconfined aquifers exist above the clay confining unit. sediments

  9. Basics Recent Deposits Sands Miocene Clay 25 to 5 Mya Jurassic To Miocene CaCO3 200 Mya to 25 Mya

  10. Sinkholes and springs are a product of the geology of Florida Solution cavities exist in the limestone Water in cavities is under pressure Sinkholes: collapse of material into cavities Springs: water bursts through thin confining units

  11. Springs Springs form best when the overlying clay layer is thin.

  12. Springs Hawthorne Thickness First magnitude: 100 ft3/s Florida: 27 of 78 nationally (64.6 million gallons per day) Thin or absent 30 – 200 ft sandy 30 – 200 ft clayey Confining unit less than 100 feet thick or is absent > 200 ft thick

  13. Poe Spring Manatee Ginnie Little Devil http://www.underwaterflorida.homestead.com/springs.html

  14. Florida’s Dominant Aquifer Systems Florida is the largest groundwater user east of the Mississippi

  15. Biscayne Aquifer Unconfined Confined Floridan Aquifer Intermediate aquifer

  16. Sea Levels Temporary reestablishment of carbonate deposition

  17. The Floridan Aquifer

  18. The Floridan Aquifer Confined • 100,000 square miles • southern Alabama • southeastern Georgia • southern South Carolina • all of Florida Miocene clay deposits (Hawthorne) are the confining unit

  19. Withdrawals 3 billion gallons per day of freshwater withdrawn Agriculture – 39% Domestic use – 47% Industry – 8.5% Misc.- 5.5%

  20. Water-Bearing Units A thick sequence of carbonate rocks (limestone and dolomite) CaCO3 + MgCO3 The thickest and most productive formations of the system are the Avon Park Formation and the Ocala Limestone of Eocene age (37-58 million years ago)

  21. 600 1200 1800 2400 Thickness In feet 3000

  22. Biscayne Aquifer surficial Floridan Aquifer Intermediate aquifer

  23. The Intermediate Aquifer System

  24. The Intermediate Aquifer System • Between the surficial aquifer system • and the Floridan aquifer system • Used where the underlying Floridan aquifer system is • deeply buried and/or contains brackish or saltwater. • Clay confining units are above the Floridan and • below the surficial aquifer. • Artesian, but yields less • water than the Floridan • Sand, limestone, shell beds • 298 million gallons per day

  25. Intermediate Aquifer confined Sand, shell, limestone

  26. The Intermediate Aquifer System Polk Co. Collier Co.

  27. Polk: 120 ft Main source of water supply for Charlotte, Lee, and Sarasota counties. flow

  28. Comparison Floridan Aquifer: Intermediate Aquifer: Withdrawal = 3 billion gal/day Withdrawal = 298 million gal/day Intermediate aquifer is used where the Floridan is inadequate

  29. Surficial aquifers: The Biscayne

  30. Surficial aquifers Water stored above an impermeable layer and unconfined at the surface

  31. Surficial aquifers Soils or Geologic Materials water high conductivity low conductivity

  32. Biscayne Aquifer 4,000 square miles Dade Broward Palm Beach

  33. Biscayne Aquifer Plio-pliestocence highly permeable sand, limestone, sandstone, shells, marl 786 million gallons/day 70 % for public supply Miocene Eocene low-permeability sandy silt Marls: carbonate-rich muds containing clays and calcite Oolitic limestone: spheroidal carbonate grains with a mineral cortex

  34. Thickness 240 ft

  35. Water in the Biscayne

  36. Recharge and Flow Recharge Flow

  37. Pesticides, fertilizers, landfills, septic systems, injection wells Injection well Salt water

  38. Salinization pumping

  39. Coastal Canals

  40. Inland Canals Flood Control pollutants

  41. Three Major Florida Aquifers Floridan Aquifer: Intermediate Aquifer: Biscayne Aquifer Withdrawal = 3 billion gal/day Withdrawal = 298 million gal/day Withdrawal = 786 million gallons/day Total = 4.084 billion gallons/day

  42. Biscayne Aquifer Unconfined Confined Confined Floridan Aquifer Intermediate aquifer

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