l1 variety in supply ap

How does freshwater vary globally?

1. Distribution of fresh water

• What is the link in all these images?

LO: How does freshwater vary globally?

What are aquifers?


What are aquifers?

• Aquifers are underground stores of fresh water. They can hold millions of litres of water but take a long time to be filled.

• Sometimes they are being drained by humans faster than they are being replenished naturally by rainfall.


1. Distribution of fresh water

• With 70% of the earth covered in sea, often it is nicknamed The Blue Planet


1. Distribution of freshwater

• 97 % of all water is too salty for us to drink.

• That means 3% is left as freshwater. Two thirds of this is stored in ice and difficult to get to. Which leaves one percent left for us to use.


2. How does freshwater availability vary globally, nationally and locally?

• Major rainfall is away from major centres of population so there is a problem of getting water to where people need it.

• Therefore the availability of freshwater varies hugely globally, nationally and locally too.


Locally – Ross and Cromarty (North Scotland)


3. Why do some parts of the world have a water surplus or deficit?

• Surplus = Too much water • Defect = Lack of water• Factors influencing this are:1. Levels of precipitation in area. 2. Level of evaporation in area.

There could be an average volume of rain but a lot is evaporated quickly.

3. Level of transpiration There could be a lot of plants using soil moisture and releasing it back to the atmosphere through their leaves (transpiration)

4. Levels of evapotranspiration A combination of both evaporation and transpiration.


4. How and why has the supply and demand for water changed in the past 50 years?

• Turn to your neighbour and tell them all the things you use each day that involves water?



• Turn to your neighbour and tell them all the things you use each day that involves water?

• Did you get these?


Research time! Copy out the table below and complete it in your books.

Population Growth Climate Change Level of developmentof a country

What has happened?

• The worlds population is now over …….

• ………………………

• ……………..

• ……………..

• ……………..

• ……………..

How does this impact water supply and / or demand?

• Every person ‘eats’ 3496 litres of water a day in the UK.

• ………………………..

• ……………..

• ……………..

• ……………..

• ……………..


Practice question

1. Using the map describe the distribution of the global supply of water (4 Marks)

Describe and explain the changes to global fresh water availability over time (6 marks)


But did you think about these things?

Have a look at this


http://www.angelamorelli.com/water/


• Virtual Water = The freshwater used to produce something. E.g. It takes 15 400 litres of water to make a kg of beef.



• There are three main areas which have impacted supply and demand over the last 50 years;

1. Population Growth.

More people means more demand for water. The worlds population has grown exponentially (rapidly) over the past 50 years. This is true for ‘virtual water’.

2. Climate Change.

Precipitation is becoming unreliable in some areas of the world, e.g. overall it may be lower each year or it may come in more intense showers.

3. Development.

The more developed a country is the more water it will use. This is true of ‘virtual water’ too.


Plenary

• Summarise the lesson in 5 words to your neighbour.


l1 variety in supply ap

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