This document provides an overview of various water sources and topics. It discusses where water is found on Earth, with 71% of the surface covered by water. Rivers are described as transporting water and providing supply and electricity via dams and power stations. Oceans and seas hold almost all of the world's liquid water in the form of salt water, with salinity varying depending on temperature. Currents, tides, and waves in oceans are also covered. The document defines lakes and their various origins from precipitation, rivers, or glaciers. Groundwater and glaciers are sources of drinking water, and groundwater also supplies rivers and lakes. Finally, problems related to water such as consumption, distribution, pollution, and acid rain are

1. Unit 3
WATER

2. 1- Where is water found?
- On Earth: 71% of the Earth’s surface is covered by
water (salt water is 97%, fresh water just 3%).

4. Activities
Exercises 1 and 2 on page 25.

5. 2- What are rivers?
-River source
-Tributaries
-Basin
-Flow (depends
on the season)

6. The importance of rivers
-Transport
-Water supply: Canals, reservoirs
-Electricity: dams, power stations

7. Activities
Exercise 1 on page 26

8. 3- What are oceans and seas?
They hold almost all the world’s liquid water,
that is salt water.
Salinity is different depending on if the sea is
warmer or colder.
Warm = + salt
Cold = - salt

10. The importance of oceans and seas
-Food
-Raw materials
-Energy
-Tourism
-Transport

11. 4- What are currents, tides and waves?
Map of ocean currents

12. Ocean currents

13. Tides

14. Waves

15. Activities
Exercise 1 on page 28.

16. 5- What are lakes?
Different terms:
-Lake
-Lagoon (small)
-Inland sea (salt water)
Different origins:
-Precipitation
-Rivers or groundwater
-Glaciers

17. Activities
Exercise 1 on page 29.

18. 6- Where are groundwater and glaciers found?
GROUNDWATER. Aquifers.

19. Hot and cold springs

20. The importance of groundwater
-Drinking water
-Source for rivers and lakes
-To grow plants

22. Glaciers

23. Icebergs

24. Homework
Activity 1 on page 30.

25. 7- What problems are related to water today?
WATER CONSUMPTION AND DISTRIBUTION
-3% Fresh water -> 0,014% available
-Increase in population -> increase in
consumption
-Bad distribution
-Consequences: droughts or floods

27. Water pollution
and acid rain

29. Activities
Exercises 1 and 3 on page 31.

30. Work at home
Exercises 1, 4 and 5 on pages 32-33.