1. Groundwater
Chapter 10 Notes

2. Hydrosphere Oceans (97%) Polar ice caps/glaciers (2.15%)
Groundwater (0.31%)
Lakes (0.009%)
Atmosphere (0.001%)
Rivers and streams (0.0001%)

4. Groundwater
All water on land comes from the ocean, through evaporation and precipitation.
Infiltration: precipitation that trickles into the ground to become groundwater

5. Porosity Water is stored in pore spaces in the ground
The percentage of pore spaces in a rock or sediment is the porosity
Can vary from 2% to 50%

6. Zone of Saturation

7. Zones of Aeration and Saturation

8. Permeability
The ability of water to move through sediment and rock is called permeability
Aquifers are permeable rock layers that allow groundwater to flow through them
A layer that is impermeable to ground water is an aquiclude

9. Aquifer

10. Springs Emergence of springs Hot springs/geysers
Groundwater emerges wherever the water table intersects Earth’s surface
Springs tend to form where an aquifer and an aquiclude are in contact
Most often occur on a slope or hillside

11. Cave Formation
A cave is a natural underground opening with a connection to the surface
Most caves form in limestone bedrock when limestone is dissolved by groundwater:
CO2 + H2O  H2CO3
Carbonic acid reacts with limestone to produce soluble ions

12. Karst

13. Groundwater Deposits
Calcite in ground water precipitates to form new mineral deposits (stalactites, stalagmites, etc.)

14. Wells Wells are used to draw water out of an aquifer
Overpumping lowers the water table and creates a cone of depression

15. Artesian Wells
Artesian wells produce water under pressure due to recharge at a higher elevation

16. Threats to our Water Supply
Overuse: groundwater supplies can be depleted if pumped faster than the recharge rate (Ogallala Aquifer)
Subsidence: sinking of ground elevation when water table drops
Pollution (next slide)

17. Pollution
Chemicals, sewage, salt, radon