1. 1. Groundwater 101 Fundamentals of Hydrogeology and a few Texas aquifers TAGD Training November 16 2017 Dr. Joe
2. 2. Dr. Joe? Hydrogeologist Baylor University
3. 3. Dr. Joe Hydrogeologist Baylor University Texas land owner wells (registered)
4. 4. Dr. Joe Hydrogeologist Baylor University Texas land owner wells (registered) springs
5. 5. Dr. Joe Hydrogeologist Baylor University Texas land owner wells (registered) springs rivers/streams Grandparent
6. 6. Outline A. What is Hydrogeology? B. What is Groundwater? C. How does GW flow? D. Basic GW concepts E. GW-ABCs (Terminology) F. Affects of wells G. Water Chemistry H. A few Texas aquifers I. Management challenges
7. 7. A. What is Hydrogeology? The study of groundwater Hydrology Surface water Geohydrology Engineer? Subsurface hydrology Engineer? Hydrogeology Geologist Complex and Difficult Rocks are different in places Groundwater flow changes And you cant see it!
8. 8. Hydrogeology Complex and difficult not secret and occult Hydro and geology The study of Groundwater
9. 9. B. What is Groundwater? the saturated zone
10. 10. The Earths Water Oceans and Inland Seas 97.208% Ice (mostly Greenland and Antarctica) 2.15 % Groundwater 0.62% 97.5% Surface water 0.0091% Lakes 0.009% Rivers and Streams 0.0001% Other 0.00604% Soil water 0.005% Atmosphere 0.001% Biosphere 0.00004%
11. 11. C. How does groundwater flow? the Ohio Supreme Court in Frazier v. Brown:48 (1861) In the absence of express contract and a positive authorized legislation, as between proprietors of adjoining land, the law recognizes no correlative rights in respect to underground waters percolating, oozing, or filtrating through the earth; and this mainly from considerations of public policy: (1) Because the existence, origin, movement, and course of such waters, and the causes which govern and direct their movements, are so secret, occult, and concealed that an attempt to administer any set of legal rules in respect to them would be involved in hopeless uncertainty, and would, therefore, be practically impossible.
12. 12. Darcys Law 1856 Q = KIA
13. 13. Darcys Law
14. 14. Darcys Law Q = KIA Groundwater flows from higher to lower head
15. 15. Groundwater contour maps and flow directions
16. 16. Our activities affect our wells
17. 17. Darcys Law 1856 Q = KIA
18. 18. D. 2 Groundwater concepts 1. Aquifer Material that can store and transmit water easily 2. Flow system Recharge to discharge
19. 19. Aquifer concept Aquifer - material that can store and transmit water easily Aquitard material that retards groundwater flow (also Confining Bed) Aquifer (sand) Confining bed (shale)
20. 20. Aquifer concept 1. Unconfined (water table) aquifer an aquifer that has a free water surface (water table) on the top. 2. Confined (artesian) aquifer an aquifer where the water rises above the top of the aquifer or above the bottom of the overlying confining bed.
21. 21. Aquifer concept 1. Unconfined (water table) aquifer an aquifer that has a free water surface (water table) on the top.
22. 22. Aquifer concept 2. Confined (artesian) aquifer an aquifer where the water rises above the top of the aquifer or above the bottom of the overlying confining bed.
23. 23. Confined aquifer
24. 24. Unconfined and Confined aquifers
25. 25. 2 Groundwater concepts 1. Aquifer Material that can store and transmit water easily 2. Flow system Recharge to discharge
26. 26. Groundwater flow systems recharge to discharge
27. 27. Local, Intermediate, and Regional flow systems
28. 28. E. GW ABCs: terminology Porosity Hydraulic conductivity Q=KIA Similar to permeability Transmissivity T = K x b
29. 29. Hydrogeological terminology Storativity or Storage Coefficient S Specific Yield Sy
30. 30. Hydrogeological terminology Homogeneous (Homogeneity) The same everywhere Heterogeneous (Heterogeneity) Isotropic (Isotropy) The same in all directions Anisotropic (Anisotropy)
31. 31. F. Groundwater and Wells
32. 32. Flow to wells
33. 33. Overlapping cones of depression
34. 34. G. Water chemistry H2O H180 O90 Dipolar The universal solvent
35. 35. Water - the universal solvent
36. 36. Electrical Conductance Charged ionic species increase conductance therefore, Ec = TDS? TDS = A x (Ec) where A = .55 to .75 or about .67
37. 37. Chemistry changes with depth
38. 38. H. A few Texas aquifers Ogallala
39. 39. Ogallala Aeolian wind Fluvial water
40. 40. A few Texas aquifers Trinity aquifer Major aquifer unconfined outcrop confined downdip
41. 41. Sand clay and Ls
42. 42. Discovery, Value, and Problem The first artesian well drilled in Waco in 1889 1830 ft deep Flowed at the surface ~400,000 gal/d Waco advertized as Geyser City by 1894, some wells ceased flowing at the surface
43. 43. ?
44. 44. A few Texas aquifers Edwards BFZ
45. 45. Northern Segment Barton Springs Segment San Antonio Segment The Edwards BFZ aquifer 48 SALADO SAN ANTONIO AUSTIN (I-35 CAC, 2011)
46. 46. Northern Segment of the Edwards BFZ aquifer, Central Texas (Jones, 2003)
47. 47. fractures cave losing stream sink hole
48. 48. Fractures and dye tracing
49. 49. N Linear features 52 Lineation is directly in line with Big Boiling Desktop measurement: 213 Field measurement: 220
50. 50. I. Management challenges
51. 51. Underflow TCEQs definition at 30 Tex. Admin. Code 297.1(56) (56) Underflow of a stream--Water in sand, soil, and gravel below the bed of the watercourse, together with the water in the lateral extensions of the water-bearing material on each side of the surface channel, such that the surface flows are in contact with the subsurface flows, the latter flows being confined within a space reasonably defined and having a direction corresponding to that of the surface flow.
52. 52. Hyporheic Zone
53. 53. Underflow (56) Underflow of a stream--Water in sand, soil, and gravel below the bed of the watercourse, together with the water in the lateral extensions of the water-bearing material on each side of the surface channel, such that the surface flows are in contact with the subsurface flows, the latter flows being confined within a space reasonably defined and having a direction corresponding to that of the surface flow.
54. 54. Underflow
55. 55. Underflow
56. 56. Models
57. 57. Uncertainty Often quoted: All models are wrong, but some are useful Box and Draper (1987)
58. 58. Uncertainty Often quoted: All models are wrong, but some are useful Box and Draper (1987) The second half: ...the practical question is how wrong do they have to be to not be useful.
59. 59. Questions?