1. Groundwater
Chapter 16

2. Groundwater Aquifer Water beneath Earth’s surface
Body of rock or sediment that stores groundwater
Allows flow of groundwater

3. Aquifers Need porosity and permeability Porosity Permeability
Percentage of aquifer total volume that is open spaces
Permeability
Connectivity of pores
Allows water to flow through the rock

4. Aquifer Zones Zone of Saturation Zone of Aeration
Pore space completely filled with water
Water table – upper surface of this zone
Zone of Aeration
Lies between water table & Earth’s surface

6. Water Table Depth Depends on
Surface topography (contours usually match local topography)
Permeability of aquifer
Rainfall amount
Rate of human use of water

7. Groundwater Replenishment
May replenish slower than it is used
Recharge zones
Area where water enters an aquifer
Sometimes labeled
Near oceans, salt water can flow into an aquifer if too much pumped

9. Saltwater Can Infiltrate Fresh Water

10. Wells & Springs Wells Hole dug to the water table to get water
Pumping water forms cone of depression
Well might run dry

11. Wells & Springs Springs
Natural flow of groundwater to Earth’s surface where the ground dips below the water table
Usually found in rugged terrain
Can dry up as water table changes

13. Artesian Formation
Sloping layer of permeable rock sandwiched between 2 layers of impermeable rock
Caprock – impermeable rock layers
Can form artesian well
Cone of depression:
pumping water from
the well lowers the
water table around it

14. Artesian Wells
Well through which water flows freely to the Earth’s surface (in normal wells, it has to be pumped)
Artesian formation creates pressure to force water out of the ground
If caprock cracks, can get an artesian spring or well

15. Artesian Well vs. Aquifer
In a normal aquifer, rock layers
are horizontal and lack a cap.
In an artesian formation,
the permeable rock layer
slopes and is covered by an
impermeable layer called caprock.

16. Hot Springs Groundwater passes near magma ands heats up to above 37oC
Travertine – mineral deposits from cooled hot springs
Mud pots - muddy hot springs clay
Paint pots – brightly colored clay

17. Hot Spring

18. Deposits

19. Mud Pots

20. More Mud Pots

21. Paint Pot

22. Geysers
Hot springs that periodically erupt from surface pools or through small vents
Steam builds up underground and eventually erupts through the vent when the pressure builds up
If there is no steam build up underground, there is no eruption (and therefore, no geyser).

23. Geysers

24. Weathering by Groundwater
Groundwater passes through soil and other organic minerals and forms carbonic acid
Groundwater dissolves and breaks down minerals in the rock

25. Caverns A large cave Stalactites Stalagmite Column
Calcite deposited on cave ceiling
Stalagmite
Calcite deposited on cave floor
Column
Stalagmite meets stalagtite
How caverns form: groundwater flows through cracks & carbonic acid dissolves limestone and makes cracks bigger. This eventually makes a cavern.

26. Stalactite
Stalagmite

27. Sinkholes
Circular depression that forms at the surface when rock dissolves , when sediment is removed, or when caves or mines collapse
Subsidence sinkhole
depression in ground
Collapse sinkhole
open hole in the ground

28. Florida River Runs Into Sinkhole

29. Sinkhole

30. Sinkhole

31. Sinkhole

32. Natural Bridges
Uncollapsed rock between 2 adjoining sinkholes or when two sides of a cavern collapse

34. Karst Topography
Type of topography characterized by sinkholes, caverns, and underground drainage
Forms on LIMESTONE and other soluble rock

35. Karst Topography