1. Paleozoic Karst Aquifers in the Mid-Continent

2. Topics Overview Conceptual model Aquifer Properties Dynamics
Water quality
Karst Geomorphology
Modeling difficulties

3. Floridan
Edwards
Roswell
Paleozoic carbonates in mid-continent

4. Mississippi embayment
Illinois basin
Michigan basin
Mississippi embayment
Wisconsin arch
Ozark plateau
Finlay arch
Cincinnati arch
Lexington dome
Nashville dome

6. Biscayne Aquifer (Pleistocene)
Floridan Aquifer (Tertiary)
Edwards Aquifer (Cretaceous)
Permian (Roswell in NM and Blaine in TX)
Mississippian
Silurian
Cambrian-Ordovician (Nashville and Lexington, Ozarks, Arbuckle Mtns in OK)
Paleozoic Karst in the Appalachians

8. Conceptual Models

9. Mechanism for cave development
Flow through small fractures, diffuse flow, similar to porous media
Mechanism for cave development
Conduit development and migration of the water table

10. Conceptual model for Paleozoic Karst Aquifer,
Based on Mammoth Cave Area, KY
Topo divide
Watershed divide

13. Erosion of base level stream causing multiple levels of caves
Erosion of base level stream causing multiple levels of caves. Based on Mammoth Cave area

15. Properties Intact Limestone: Low K and S Karstified LS: High K, Low S
Epikarst (surface): Low K, High S
Hydraulic diffusivity: T/S

16. Water level response to rainfall
Well in Big Clifty Sandstone
Water level in well
and local rainfall, Ozark Plateau
Well in St. Louis LS
Rainfall in Mammoth Cave Area
Water level response to rainfall
Large Kb/S = fast response (rise and fall)
Small Sy = large magnitude

17. Water Quality

18. Depth to saline ground water

21. Vulnerability of Karst Aquifers to Contamination
Sinkholes funnel surface contamination into cave conduits.
Rapid transport in caves (km+/day) moves contaminants away from source
Thin soils provide minor sorption/retention
Turbulent flow transports clay. Increase tubidity and contaminants sorbed to clay

22. Important Hydro-Geomorphic Features in Karst Aquifers
Sinkholes: Recharge, ground stability
Estevelles: Recharge and discharge
Vertical fractures w/dissolution: Recharge/discharge
Epikarst: Storage
Solution channels: water pathways; high velocity flow
Springs: Focused discharge

23. Porosity

25. Sinkholes and Estevelles

27. Sinkhole collapse related to hydrogeology

28. Flooding caused by sinkholes

29.                                                                                            .
Sinkhole risk evaluation. Controlled largely by underlying formation. Mississippian produces most sinkholes

30. First-order spring. Discharge > 100 cfs
Springs

31. Discharge from springs
Percent of days when discharge equaled or exceeded
2 springs in Ordovician rocks
2 springs in Silurian rocks
Discharge Probability Plots
Discharge from springs
Hydrograph for karst spring
Discharge as function of time
recharge recession recharge recession recharge recession

32. Vertical fractures and faults

33. Karst systems and biodiversity

34. Blind Salamander
Blind Cave Fish
Cave Ecosystems

35. Modeling Flow in Karst Conduits
Porous Aquifer, Darcy:
Conduit, Manning:
Fundamental difference in physics of flow
Hr: hydraulic radius=x-section area/wetted perimeter
n = wall roughness
Conduit geometry and wall roughness highly variable
—how to determine in the field for an aquifer?

37. Ozark Plateau Aquifer System

38. Stratigraphy of the St. Francois and Ozark Aquifers caves typically underlie sandstone
Pb-Zn

40. Geology

43. Thickness of Springfield Aquifer
Ozark Aquifer

44. Regional potentiometric surface on Ozark Plateau and Western Interior Aquifer System

46. Cross-section on NW side of Ozark Plateau
Cross-section on NW side of Ozark Plateau. Fresh water mixes with saline water in laterally equivalent units deeper in basin.

48. Potentiometric surface in Ozark Plateau in Missouri

51. 330 Mgpd

52. Lead and zinc mining districts in Ozark Plateau
Biggest producer of Pb,Zn in the world in 1920s
Viburnum Trend Active

54. Pb and Zn concentrations in water, sediment and tissue
Site
Mining area
Lead
Zinc
Water (µg/L)
Bed sediment (µg/g)
Tissue (µg/g)
Center Creek
Tri-State
<1
370
0.3
67-270
5,600
770
Big River
Old Lead Belt
2,300
134
8-19
670
514
Meramec River --
180
12.2
140
296
West Fork of Black River
Viburnum Trend
<1-11
10-95
13-33
12-46
70-110
Strother Creek
<1-3 20
0.7
33-148
120
150
Background
<1-20
15-28
<
<1-44
43-140
57-230