1. 10.3 Sources of Fresh Water
Part 1: Run-off

2. When it rains, water… a) Evaporates  makes precipitation
b) Soaks into the ground
 called groundwater
c) Stays on the surface
 called run-off

3. Run-Off Run-off = water that stays on Earth’s surface
- Gravity pulls it downhill
 stream or river
 pond, lake or ocean

4. Run-off is important to think about
It brings good & bad things to lakes, rivers, & oceans with the water
Minerals
Nutrients
Pollution
These things affect plant and animal life

5. Run-off is important to think about

6. Factors that affect Run-off
1. Type of ground material
More run-off on rock
than soil

7. 2. Precipitation
Length of time
Amount

8. 3. Slope of the land
Steeper land
 less water absorbed
(more run-off)

10. 4. Vegetation

11. E.g., Clearcuts

12. Development (roads, cities)
Concrete doesn’t allow water to be absorbed into the ground

13. Run-off Problems Flooding Soil carried away by run-off Pollution
Soil & silt churned up  harmful to fish
Let’s think about this stuff!
Read p 376, 377, 378.
Do the Activity on p 378.
Make a drawing of the landscape, including the proposed development
“What to Do” #1 & 2
“What Did You Find Out?” #1 & 2

14. Part 1: Run-off Part 2: Drainage Basins, Groundwater & Glaciers
10.3 Sources of Fresh Water
Part 1: Run-off
Part 2: Drainage Basins, Groundwater & Glaciers

15. Drainage Basins Drainage basin =
The area of land which that drains into a body of water
E.g., in Canada, we could ask, “What is the drainage basin for the Pacific Ocean or the Atlantic Ocean?”

16. Drainage Basins Divide = High ground between two drainage basins
E.g., in Canada, the Rocky Mountains are the divide between the Pacific and Atlantic Ocean drainage basins
(aka the Continental Divide)

17. Activity 10-5 (p.382) How Big Rivers Are Made
You will:
Model small streams joining to form bigger creeks
Identify drainage basins

18. Activity 10-5 (p.382) How Big Rivers Are Made
Rules:
Each of the dots on your graph paper is the start of a small stream in the mountains
Your 20 streams will flow “downhill” (down to the bottom of the graph paper)
Which way does each stream flow?
Roll a dice!
Even: Your small stream flows downhill to the right
Odd: It flows downhill to the left
Roll your die 20 times, once for each of your 20 streams, going from left to right

19. Activity 10-5 (p.382) How Big Rivers Are Made
Rules:
How far does each stream flow?
A single stream flows one square on graph paper
What do you do after you’ve rolled the dice for each stream?
Roll the dice again to see where your streams turn next!

20. Activity 10-5 (p.382) How Big Rivers Are Made
Rules:
What if 2 streams meet?
If 2 small streams meet, it means they have joined to form one larger stream. Since the stream is larger and faster, it flows 2x the distance. (2 squares on graph paper, not 1)
If a 3rd stream joins, the stream flows 3x the distance (3 squares on graph paper)
Etc.
What if a stream goes off the page (to the side or bottom)?
The river is “finished” (has reached the ocean) and you no longer have to roll the die for it

21. Activity 10-5 (p.382) How Big Rivers Are Made
Summary of Rules:
Even: right
Odd: left
2 small streams meet: flows 2x the distance (2 squares)
3rd stream joins: 3 squares on graph paper
4th stream joins: 4 squares on graph paper
Etc.
If a stream goes off the page: stop rolling die for it
Assignment:
“What Did You Find Out?” questions at the end of the activity, #1,3,4

22. Ground Water Groundwater = Aquifer =
Water that is stored in the pores (spaces) between rocks underground
Aquifer =
A rock layer with good porosity (many pores) that holds water humans can use
Water Table
Aquifer (porous rock)
Zone of saturation (pores filled with water)
Non-porous rock

23. Ground Water
Humans build wells to access water in aquifers

24. Glaciers = large blocks or sheets of ice flowing slowly downhill
Created when piles and piles of snow are compressed to become ice
2/3 of the world’s fresh water is trapped in glaciers

25. Two Types Alpine glacier Continental glacier = mountain glaciers
= sheets of ice covering large areas of land (e.g., Antarctica, Greenland)

26. Glaciers move downhill until:
The temperature is warm enough to melt the ice (lower elevations)
They reach water and break off to form icebergs
Homework: Text p