1. Vasey’s Paradise
Groundwater discharges from the wall of Marble Canyon to form a series of natural springs.
(Grand Canyon)

3. Major Groundwater Regions of the USA
Puget Sound & Willamette Valley (alluvial basin)
Columbia Plateau (fractured lava flows)

4. Porosity = The percent void space in a rock or sediment.
It is a measure of the potential volume
of water that can be stored in a rock.

5. Permeability = The ability of a material to transmit a fluid.
It is a measure of how fast the fluid can
travel through the rock or sediment.

6. Aquifer
= A geologic unit capable of storing and transmitting water in sufficient quantities to supply wells.

7. Porosity
varies with
% Cement
Size-Sorting
Fracturing

8. Cemented Sand
Uncemented Sand

9. Types of Aquifers
Unconfined Aquifer - The permeable layer extends to the surface. It consists of an unsaturated zone separated from the saturated zone by the groundwater table.
Confined Aquifer - The permeable layer is sandwiched between less-permeable layers (aquitards or aquicludes).

10. Pores include both air and water Pores filled with water
Unconfined Aquifer
Unsaturated Zone:
Pores include both air and water
Groundwater Table
Saturated Zone:
Pores filled with water

11. Water Table • The top of saturated zone of groundwater
• The level to which water will rise in a hole
• The level to which water will rise in an
unconfined aquifer

12. Dynamics of an Unconfined Aquifer
in a Temperate Climate

13. During the Wet Season…

14. During the Dry Season…

15. Darcy’s Law
An equation by which the discharge (rate of flow) of groundwater can be calculated.

16. Darcy’s Law
Q = A ( K x S )

17. Darcy’s Law Q = Discharge A = Cross-sectional area of flow
Q = A x ( K x S ) = A x ( K x H / L )
Q = Discharge
A = Cross-sectional area of flow
K = Permeability (hydraulic conductivity)
S = Slope of water table = ( H  L )
H = vertical drop
L = flow distance

18. Hydraulic gradient = 1 m / 1000 m
V = ( K x ( h1 - h2 ) / ( d x n )
V = (60 m/day x 1 m) / (1000 m x 0.3)
1 m
Permeability = 60 m/day
Porosity = 30% (=0.3)
Hydraulic gradient = 1 m / 1000 m

19. Darcy’s Law

20. The recharge area of a confined aquifer is the area where rainfall enters (recharges) the aquifer. The pressure surface is the level to which water will rise in wells in confined aquifers.

21. Note the Difference Between:
Groundwater Table: The level to which water will rise in an unconfined aquifer
Pressure Surface: The level to which water will rise in a confined aquifer *
* If the pressure surface is above the ground surface, the water will flow freely out of the ground. Such wells are called flowing artesian wells.

22. Confined Aquifer Recharge Area: Pressure Surface: Flowing
where the confined aquifer
is recharged by infiltration
Pressure Surface:
Height to which water will rise
in the confined aquifer
Flowing
Artesian Well

24. Pressure Surface
Ground Surface
Flowing artesian well

25. Artesian Well in Glacial Sands & Gravels (MA)

26. Perched Water Table

27. Formation of a Cone of Depression

28. The Ogallala
Aquifer:
“Mining Groundwater”

29. U.S. Groundwater Withdrawals: 1950-1995

30. Fissures and depressions
caused by
ground subsidence
due to overpumping
of groundwater
(Antelope Valley, CA.
January 1991.
625 meters long!)

31. The Winter Park Sinkhole, Florida (Photo by Leif Skoogfors)

32. Saltwater - Freshwater Interface
Dynamics of the
Saltwater - Freshwater Interface

33. The thickness of the fresh groundwater floating on top of the salty groundwater is affected by the balance between
groundwater
recharge and
discharge

34. If the rate of discharge increases too much (by overpumping), the saltwater will rise, causing saltwater intrusion
in the well.
Inverted
Cone of depression

35. Carlsbad Caverns, NM)
Stalagmite
Stalactite

36. Some Major Features of a Karst Landscape

37. Subsurface Features of a Karst Landscape

38. Some Human Activities that Can Contaminate Groundwater

41. Cape Cod Sewage Plume (MA)

42. Detergent in groundwater (Cape Cod, MA).
From abandoned military base (wastewater & sewage disposal).

43. (Maryland)

46. Hand-dug well in Sinai.
Ancient river sediment.

48. Lancaster County, PA