Topic 4: Water World Revision
The Hydrological Cycle
Watch this clip
Water on planet Earth
• All water: 97% salt water, 3% freshwater
• Freshwater: 75% glacier ice, 24%
groundwater & 1% surface water
• Surface water : 81% soil moisture, 16% lakes,
2% rivers & 1% biomass
The hydrological cycle is a system
• What do we mean by a system?
• How can systems be closed/open?
A system has inputs, stores, flows (transfers)
and outputs
The hydrological system is a closed system –
water goes around and around, no water is
lost or added
Define:
Evaporation
Condensation
Precipitation
Infiltration
Transpiration
Percolation
Groundwater flow
Through flow
The Hydrological Cycle
Energy from the sun __________ water from the
sea and land. The v__________ rises, cools
and condenses to form __________ which are
blown by the wind. The water falls back to the
ground as _______, hail or snow. The water
either travels over the land in _________ or
sinks into the ground. Eventually most water
will return to the sea.
Click on the photos to complete the
key terms
Key terms
• Inputs – goes into the cycle
• Flows – transfers water from one source to the
other
• Stores – holds water
• Outputs – water goes back into the atmosphere
What examples can you think of?
Exam question
Explain why the biosphere and lithosphere are
important to the hydrological cycle (4)
Discuss in pairs:
More than likely there will be ‘Water Wars’ in
the future
Explain how water is being used
unsustainably
Population
increase
electricity
industrialisation
tourism
Climate change
urbanisation
Many parts of the world are
experiencing water stress
Many lakes, rivers and groundwater supplies are
drying up due to overuse.
Describe the distribution of physical water scarcity(3)
The Sahel lies in which countries?
Lack of rainfall has resulted in
desertification. Watch this clip:
What is desertification?
Try to come up with your own definition
Desertification – the spread of desert-like
conditions
Desertification and Degradation
Desertification is the persistent degradation of
dry land ecosystems so land conditions turn to
deserts.
Degradation is primarily driven by land
management (human causes). It is the spread
of desert conditions caused by pressures put
on the land by human activity.
What is the Sahel like?
•
•
•
•
Semi-arid area
Periods of rainfall and drought
Supports small bushes
Windbattered trees
Case study
Describe how water shortage might
affect people (4)
How do we damage water supplies?
•
•
•
•
Domestic
Agricultural
Industrial
Transport
Sewage disposal
(MEDCs and LEDCs)
Industrial pollution
(could use China)
Intensive agriculture
Deforestation
(Cutting down trees)
(Taking too much
Over abstraction water out)
Building dams/reservoirs
Exam Style Question
Using examples, show how different water uses
can have unintended effects (4 marks)
Explain how water usage can be unsustainable
(6)
Large-scale water
management projects
The Three Gorges Dam, China
Copy and complete:
Advantages
Social
Economic
Environmental
Disadvantages
Describe the economic impacts of a
named large scale water management
scheme (6)
Small scale
water management schemes
Rainwater harvester
Rope pump
WaterAid uses
appropriate/intermediate technology
Development schemes which meet the
needs of local people and the
environment in which they live
How are the schemes
SUSTAINABLE?
•
•
•
•
•
•
•
The needs of the community
Available water sources
Local financial conditions
Local geographical conditions
Local availability of materials for construction
Local availability of labour for construction
Local availability of spare parts
A water pump must be
sustainable, which means it
must
be able to be fixed locally,
cheaply and quickly. A rope
pump is a simple technology
that can be constructed from
recycled parts like bicycle
wheels, scrap metal and plastic.
WaterAid’s partners train and
support local people to
maintain the pumps and in
some cases manufacture them.
Rainwater harvesting
Using named examples, describe and
explain how SMALL SCALE
management schemes are often
sustainable (6)
Exam Practice
Read the question carefully. WHAT is it asking you?
How many marks are available?
What is the key point you want to get across? Does
it relate to the question?
2+2 3+1
3+3
Using examples, explain how water use could be
made more sustainable (4)