1. Click here for an animation
The Water Cycle
                                             
Click here for an animation

2. Increase in runoff with urbanization
Decrease in infiltration

3. Groundwater
Groundwater is simply water under the ground where the soil is completely filled or saturated with water. This water is also called an aquifer.

4. Groundwater moves underground from areas where the elevation is high, like a hilltop, to places that are lowland areas.
Water movement is slow and might move anywhere from less than a millimeter up to a mile in a day.

5. Groundwater
Where the water table meets the land surface, a spring might bubble up or seep from the ground and flow into a lake, stream, or the ocean.

6. Groundwater
Ground water that meets the land surface also helps keep rivers, streams, lakes and wetlands filled with water.

8. Zone of Aeration: area where the pore spaces in the rock/soil are empty of water
Water Table: boundary between zone of saturation & zone of aeration; wells must go below the water table to reach water
Zone of Saturation: area where the pore spaces in the rock/soil are filled with water

9. Porosity and Permeability
Permeability: how quickly water can travel through a material
Porosity: the percent of a material’s volume that is pore space

10. Groundwater

11. Dangers Associated with Groundwater

12. Effects of Over-Pumping a Well

14. Sinkholes from groundwater overpumping, Antelope Valley, CA
Dust storm during Dust Bowl in Kansas, when overpumping from wells & a drought caused farmers to ‘overspend’ the water budget
Sinkholes from groundwater overpumping, Antelope Valley, CA

15. CONTAMINATED?!

16. Caves
Limestone is a common bedrock that dissolves more easily than some types of rock. The carbonic acid found in groundwater dissolves the calcite found in limestone. Chemical weathering changes the calcite into clay increasing the porosity of the limestone left behind.

17. Caves
Over time as more and more water flows through cracks in the limestone bedrock, the carbonic acid dissolves the limestone and carries it away in solution. After thousands of years, these cracks become larger eventually forming a network of underground tunnels. These caverns, or caves can be many miles long and hundreds of feet deep.

18. Cave Formations
When water drips from the roof of a cave, calcite is deposited. Slender deposits called stalactites hang like icicles from the roof. On the cave floor beneath the stalactites, a rounded mass called stalagmites form. When they meet, a column is formed.

19. Entrance to Mammoth Cave National Park-Kentucky

22. Soda Straws

23. Helictites

24. Chandeliers

25. Flowstone is sheet-like which includes draperies/curtains.

26. Cave “Bacon”

31. Luray Caverns, VA
Observe an animation of cave formation.

32. Karst Topography
They are regions characterized by caves, sinkholes, lost rivers or sinking streams, and underground drainage.

33. Karst Topography forms in areas with bedrock made of calcite like limestone (or dolomite).

34. Karst areas of the U.S. shown in green.

35. Development of Karst Topography
Step 1: Acidic groundwater dissolves limestone. Then the water table drops, leaving empty caves.
Step 2: Ground above the caves is eroded away.
Step 3: Thin rock above the cave collapses, creating a sinkhole.

38. Winter Park, FL

39. Sinkhole, Shenandoah Valley, VA

40. Because rainwater drains through sinkholes, there are few surface rivers in Karst regions.

43. Lost or sinking streams form when the surface stream disappears underground and flows out of a cave many miles away.

44. Artesian Formation

45. Artesian Well