topic 4: water world revision the hydrological cycle
TRANSCRIPT
Topic 4: Water World Revision
The Hydrological Cycle
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:
EvaporationCondensationPrecipitation InfiltrationTranspirationPercolationGroundwater flowThrough 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
industrialisation
Climate change
electricity
urbanisation
tourism
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)
Over abstraction
(Taking too much 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 Disadvantages
Social
Economic
Environmental
Describe the economic impacts of a named large scale water management scheme (6)
Small scale water management schemes
Rainwater harvesterRope 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 mustbe able to be fixed locally, cheaply and quickly. A ropepump is a simple technology that can be constructed fromrecycled parts like bicycle wheels, scrap metal and plastic.WaterAid’s partners train and support local people tomaintain 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)