1. Lakes
Where are the world’s largest lakes?

2. Lakes

4. Lakes
A lake is a large body of relatively still water, surrounded by land

5. Lakes Oligotrophic (“few nutrients”) low nutrient supply
low primary productivity
clear water, few plants & fish

6. Lakes Eutrophic (“good nutrients”) excess supply of nutrients
high primary productivity
murky water, large phytoplankton population

7. Nutrients in Lakes

8. Lakes Productivity: Oligotrophic - low productivity
Mesotrophic - moderate productivity
Eutrophic - high productivity

9. Warm-Up
How do humans protect ourselves from floodwaters?

10. Altering the Availability of Water
Levees - an enlarged bank built up on each side of a river to prevent flooding

11. Altering the Availability of Water

12. Altering the Availability of Water
Dikes - similar to a levee, but built to prevent ocean waters from flooding adjacent land
Delta-Works-/1469.html

13. Altering the Availability of Water
Dams - a barrier that runs across a river or stream to control the flow of water
Reservoir - the area where water is stored behind the dam

14. Altering the Availability of Water
Hoover Dam

17. Lake Mead 2013 vs. 2014

19. The Hoover Dam

20. Dams & Reservoirs

21. Altering the Availability of Water
Fish ladders - a set of “stairs” with water flowing over them to help migrating fish get upstream of a dam

22. Altering the Availability of Water
Aqueducts - canals or ditches used to carry water from one location to another

23. Destruction of Aral Sea23

24. Destruction of Aral Sea24

25. Destruction of Aral Sea
s/WorldOfChange/aral_sea.php

26. Destruction of Aral Sea

27. Destruction of Aral Sea
“Man is a complex being: he makes deserts bloom and lakes die.” 
~Gil Stern

30. Population Growth

32. What do you think?
Which countries use the most water per capita per day?