1. The Hydrologic Cycle Condensation Advection Evaporation
Evapo-transpiration
Precipitation
Perculation
Ground Water

2. Global Distribution of Water
It is as a
renewable resource
BUT
It is possible to withdraw it faster than nature replenishes it.
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3. Groundwater is among our most precious natural resources.
In North America groundwater provides:
53% of all drinking water for the total population
97% of drinking water for the rural population
34% of agricultural use (mostly for irrigation)

4. Key Ground Water Terms
Porosity: Volume percentage of rock that consists of voids or openings. It is a measure of the rock’s ability to hold water.
Permeability: Capacity of a rock to transmit fluid through pore space and fractures.
Rocks that allow water to flow easily are referred to as permeable, while those that do NOT are referred to as impermeable.

5. porosity: volume of voids
permeability: connectedness of voids

6. Zone of Aeration A B
perculation
Water Table
Aquifer

7. Factors that affect amount and rate of infiltration
Type of surface material (eg.gravel Vs clay)
Angle of the slope
Amount of vegetation
Type of precipitation (eg. Rain Vs snow)
Condition of the ground (eg. Frozen or water saturated)
Intensity of precipitation

8. Mines and Quarries Typically Work Below the Water Table
When worked, below-surface mines and quarries have to be actively pumped.
Stop working, and they fill up with water to the height of the water table.

9. Water flows from zones of high hydraulic pressure to low
Causes of Ground Water Movement
Water flows from zones of high
hydraulic pressure to low
hydraulic pressure!
Gravity

10. Ground Water Movement in Permeable Rock
Aeration Zone
Within a uniformly permeable rock, water table tends to mimic surface topography. Flow usually parallels sloping water table.

11. Changes in Water Table with Rainfall
During rainfall
Without rainfall

12. Influent and Effluent
When groundwater flows into streams they are called effluent. (discharge)
When the water table drops, streams become influent, (recharge)
and water leaks from the stream bed into the ground.

13. Aquifers
Aquifer: body of saturated rock or sediment through which water can move easily.
Examples: Sandstone, conglomerate, well-fractured limestone, bodies of sand and gravel

14. Confined and Unconfined Aquifers
Which type is most easily contaminated?
Which type will take longer to recover from contamination?

15. In some areas groundwater is under pressure in a
Artesian Flow/Wells
In some areas groundwater is under pressure in a
confined aquifer. This results in artesian flow, where water will rise to the surface without pumping.

16. Artesian Well

17. Wells: water quality/quantity
Well: hole drilled into the zone of saturation to access ground water. Require pumping to bring water from depth to surface.

18. Good well
Gravel; sand

19. Dry Well in Fractured Rocks

20. Effect of Groundwater Pumping
Cone of depression: conical feature in the water table that develops through well drawdown (removal of groundwater faster than recharge).
What problems could this phenomenon cause?

21. Pollution Problems Aggravated by Pumping Wells
If near an ocean?
3. Draw in nearby saltwater
1. Draw in contaminants from nearby sources
2. Draw in contaminants from downslope

22. Subsidence
4. Subsidence
Withdraw the water and aquifer material compacts irregularly. When the surface subsides, construction (buildings, pipe systems, etc.) may suffer huge damage.
It can be combatted by injecting water back into the aquifer as groundwater is withdrawn.

23. Long Beach, CA, has experienced as much as 30 vertical feet of subsidence as oil has been pumped from deep underground. The building and parking lot at the left are several feet below sea level. Walls hold back the ocean, and boat owners walk uphill from the parking lot to get onto their boats!

24. This dog is thinking “How can I use that hydrant way up there?!”

25. Areas of Mexico City have subsided as ground water has been pumped out from the sedimentary layers beneath the city.

27. Spring Controls and Types
Impermeable Rock
Joints in Bedrock
Fault Lines

28. Sources of Ground Water Pollution

29. Animal Waste

30. Industrial Toxic Waste

31. Landfill’s Impact on Ground Water Quality

32. Industrial Pollution

33. Septic Systems

36. Groundwater Issues in the Fraser Valley

37. National Geographic: Mysteries Underground
PBS Sinkholes: Buried Alive
Top 10 Sinkholes