§3.2: water in balance - part 1

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• Leerjaar 3

§3.2: Water in balance

Today

• Recap §3.1


• Explanation §3.2
• Assignments workbook

Explain the difference between the short and the long hydrological cycle

Why is not all fresh water accessible to humans?

Today

• Recap §3.1


• Explanation §3.2
• Assignments workbook

First a few facts...

Botswana has more precipitation than Sweden

1. True
2. False

In The Netherlands, there is 660 m3 of precipitation per inhabitant per year. How much is this in Egypt?

1. 200 m3
2. 120 m3
3. 50 m3
4. 30 m3

In Libya, water from the Sahara is used in the major cities (on the coast)

1. True
2. False

Learning goals 

• You can explain in which three ways an area can get water
• You understand how a water balance is put together  

Why is water not equally distributed?

Usefull precipitation 

Infiltration

Water balance

Fossil water 

Aquifer

Layer that holds water underground 

Process by which water on the ground enters the soil 

The difference between precipitation and evaporation

Water under the ground that dates back from ancient times 

The amount of water that goes into and out of an area 

Vocabulary 

Water balance	Water balans	The amount of water that goes into and out of an area
Useful precipitation	Nuttige neerslag	The difference between precipitation and evaporation (the water that is left)
Infiltration	Infiltratie	Proces by which water on the ground enters the soil
Fossil water	Fossiel water	Water under the ground that dates back from ancient times
Aquifer	Aquifer	Layer that holds water underground

An area can get water in three ways:

1. Precipitation 

2. Receiving water from other areas 

3. Through the supply of fossil water (aquifer)

1. Precipitation

Useful precipitation = the difference between precipitation and evaporation, thus the water that is left 

• What do you see in the graph?
• Does the Netherlands have much or little useful precipitation?

Chad 

The Netherlands

Botswana

Sweden

Useful precipitation

• Precipitation - evaporation = useful precipitation
  
• Precipitation which can be used by man and nature 
  

The amount of precipitation can be the same in different countries, but the useful precipitation can still differ!

2. Groundwater and rivers 

3. Fossil water 

'Old' water: water from another periods 

Aquifer

• A layer that holds water underground 
• Fossil water 

Precipitation

Infiltration

Ground water 

Porous rock (soft) 

Impermeable (ondoorlaatbaar) layer 

Aquifer in Libya 

Aquifer in Libya

Answer the following questions (in pairs):

• Why is water taken from the aquifer and not from the Mediterranean Sea?
• The neighboring country Egypt is not happy with this project in Libya: why?

Discuss the answers with another pair 

Water balance: Netherlands 

The amount of water that goes into and out of an area

Water balance: Netherlands 

• Precipitation
  
• Groundwater and rivers 
• Fossil water 

• Evaporation
• Outflow into the sea
• Water for consumption

Learning goals 

• You can explain in which three ways an area can get water
• You understand how a water balance is put together  

Why is water not equally distributed?

In which three ways can an area get water?

Explain how the water balance in The Netherlands works

Today

• Recap §3.1


• Explanation §3.2
• Assignments workbook

Homework

• Read §3.2
• Make assignment 1, 2 and 3 

Finished? 

• Have the assignments checked by the teacher 
• Make assignment 4, 5 and 6