1. Water Resources
Section #1:
Chapter 11

2. Water “The Water Planet” - abundant found in three phases fresh & salt
essential to life on Earth
renewable resource

3. The Hydrologic Cycle

4. The Water Cycle
water molecules travel between Earth’s surface & the atmosphere continuously
evaporation, condensation, & precipitation
involves all bodies of water (especially the ocean), clouds, soil, plants through transpiration, etc.

5. The Water Cycle

7. Distribution 71% of Earth’s surface is covered with water of all water
97% is salt water
3% is fresh water
most fresh water is frozen in ice caps & glaciers
only a little is actually available for human use (less than 1%)

8. This photograph tries to show what an iceberg might look like if you could see the entire thing.

9. Surface Water fresh water found in lakes, rivers, streams, & wetlands
has played a vital role in the development of human societies
cities, towns, & farms have been built near reliable sources of surface water
provides drinking water, water for crops, food (fish/shellfish), power for industry, means of transportation

10. Rice paddies built to trap water from the monsoon rains.

11. River Systems
as streams & rivers move across the land, they form a flowing network of water
from above, it looks like the roots feeding the trunk of a tree
Mississippi, Amazon*, & Nile are the largest systems because of the # of streams that drain into these river systems

12. Watersheds

13. Watersheds

14. Watersheds the area of land that is drained by a river
pollution anywhere in the watershed may end up polluting the river
water entering a watershed varies throughout the year (seasons, snow melts, droughts, growing crops, etc.)

15. Watershed Area

16. Groundwater
fresh water found under the ground that is available for human use
some precipitation flows directly into lakes & rivers while some soaks into the soil & moves down into the rocks beneath – called PERCOLATION
water moves down until it reaches a level where the rocks & soil are saturated – called the WATER TABLE

17. Water Table Levels
has peaks & valleys that match the shape of the land
water table can be close to the surface in wet regions or 100s of meters below the surface in desert regions
always in flux

18. Factors that Cause the Water Table Depth to Vary
Amount of rainfall
Time between rainfalls
Seasonal changes
Climate
Slope of the ground surface
Excessive pumping from wells

19. Water Table Fluxuations

20. Water Table Fluxuations

21. Aquifers an underground formation that contains groundwater
most consist of materials such as rock, sand, & gravel that have lots of spaces where water can accumulate, like water filling up a sponge

22. Ogallala Aquifer

23. Ogallala Aquifer
formed at the end of the last Ice Age about 12,000 years ago
makes up 1/3 of all groundwater in the U.S.
used extensively for irrigation of the Great Plains since the 1940s
starting to show its limits – wetlands are starting to disappear
fighting for its preservation

24. Porosity = % of pore space

25. Porosity pores space between grains can hold air & water

26. Pore spaces can also be filled by the cements that hold the rock particles together

27. Permeablity
The rate at which water (or other liquids) pass through the pore spaces of a rock

28. Permeability Rates
Water passes easily through materials with large pore spaces – like sands & gravels
Water passes slowly through silts
Clays are considered impermeable – water cannot pass through
Some rocks can be highly porous but have a low permeability rates (like pumice) because the pores are NOT CONNECTED!

29. The Recharge Zone
the area of Earth’s surface where water percolated down into the aquifer
environmentally sensitive areas – any pollution that enters will move into the aquifer
water cannot reach the aquifer in places that are covered with impermeable layers – including buildings & parking lots!
people must manage recharge zones

30. Recharge

31. Recharge -- Water Travel Time

32. Confined vs. Unconfined Aquifers

33. Artesian Formation

34. Wells
if you dig the hole deep enough anywhere on Earth, you will find water
well water is more reliable than surface water, and usually cleaner because it has been naturally filtered by passing through the rock layers

35. Excessive pumping from wells creates a CONE of DEPRESSION by drawing down the water table

36. Can the Water Table Survive: Overpumping Overpopulation Urbanization Industrialization