1. Water DEMAND and SUPPLY

2. Discussion – what reasons can you think of to explain this increase?
DEMAND
Global demand in water was doubled roughly every 20 years for the last 100 years.
Discussion – what reasons can you think of to explain this increase?

3. DEMAND – reasons for an increase in demand.
Population growth – During 1990 and 2010 the worlds population grew from 5.3 billion to an estimated 6.8 billion.
But population growth is NOT the only explanation……

4. And for the more wealthy….
There has been a significant increase in DOMESTIC use as development has led to an increase in standards of living. More families than ever have items including…
Flushing toilet
Showers and baths
Washing machine
And for the more wealthy….

5. There has been an increase in AGRICULTURAL use, for example through irrigation. Consider the recent changes in China…

6. There has been a significant increase in the use of water in INDUSTRY -
Water is used for cooling machinery, and the generation of electricity.

7. Study the pie charts on the right.
Water consumption is not equal. There are big differences between HICs and LICs.
Study the pie charts on the right.
DESCRIBE the differences between the charts.
EXPLAIN the differences between the charts.
Source: Witherick and Milner p17

8. SUPPLY – where do you think our water comes from?

9. Rivers – e.g. the most beautiful river ever – The River Medway
Aquifers – water is stored in porus rock. It is extracted by drilling wells and pumped to the surface.
Reservoirs – e.g. Bewl near my Mum’s house, or Tai Tm in HK. These are artificial lakes where water is trapped behind a dam

10. The relationship between DEMAND and SUPPLY
Areas of the world where demand exceeds supply are known as WATER DEFICIT AREAS
Areas of the world where supply exceeds demand are known as WATER SURPLUS AREAS

11. Study the map on the right hand side.
DESCRIBE the global pattern of water surplus and water deficit.
Can you think of any reasons to EXPLAIN it?