Water Security

Getting more water

When water supply falls short, places look for ways to secure more. Large-scale strategies move or make a lot of water. Diverting supplies redirects a river, dams and reservoirs store river water for later, water transfers carry water from a wet area to a dry one, and desalination removes salt from sea water. The Lesotho Highlands Water Project is a large transfer that sends water across the border from Lesotho to South Africa. Sustainable strategies use less and waste less, through water conservation, careful groundwater management and recycling waste water. In Rajasthan in India, rainwater harvesting lets local villages collect and store the rain they get. This module weighs the big schemes against the sustainable ones.

Water strategy words

Learn these before you match any strategy, and notice which move a lot of water and which simply save it.

Large-scale against sustainable

The two kinds of strategy pull in different directions, which is why they must be weighed rather than simply listed.

How to weigh a water scheme

A strong answer never just names a scheme. It judges one against another on real tests. How much water does it secure. What does it cost to build and what does it do to rivers and wildlife. Does moving water across a border stir tension between countries. And who actually gains, a distant city or the local village. Run a large transfer and a local scheme through the same tests, then say which suits the place and why the other fits worse.

Match the strategy to what it does

Which strategy is this?

The Lesotho Highlands Water Project sends water through tunnels and dams across the border from Lesotho into South Africa. Which strategy is this?

• A water transfer.
• Desalination.
• Rainwater harvesting.
• Simple water conservation.

Sustainable water strategies

Select the TWO strategies that make water supply more sustainable.

• Water conservation, using and wasting less
• Recycling and reusing treated waste water
• Over-abstracting groundwater until it runs dry
• Letting more water leak away unused

New daily supply

A city already supplies 500 million litres of water a day. A new water transfer adds 200 million litres a day. Add these to find the new daily supply, in million litres.

Order a water transfer

Put the stages of a large water transfer scheme in order, earliest first.

• A wet region is found with spare water
• Dams, tunnels and pipelines are built
• Water is moved to the dry region
• The dry region gains a reliable supply

Complete the facts

Moving water from a wet area to a dry one is a water _____. Removing salt from sea water is called _____. Water stored behind a dam for later use is held in a _____. Using and wasting less water is water _____.

Match the example to its type

Spot the true water strategy facts

Tap the TWO statements that are true about securing water.

• Desalination removes salt from sea water
• Water conservation makes supply more sustainable
• Large transfers never cause any tension
• Rainwater harvesting moves water across a border

Choose a scheme

Read each case and choose the best response, with a reason.

• A coastal city beside the sea has no fresh rivers but plenty of money and energy. Which strategy could secure its water?
• A large transfer moves water across a border from one country to another. What extra issue must be weighed here?
• A student says the large transfer is simply best because it supplies the most water. How could the answer be improved?

Weigh the water schemes

Compare a large-scale scheme such as the Lesotho Highlands water transfer with a local sustainable scheme such as rainwater harvesting in Rajasthan, and judge which better secures water.

• Explain how the large-scale transfer increases water supply
• Explain how the local sustainable scheme increases water supply
• Weigh the water secured by each against its cost and environmental impact
• Weigh the cross-border tension of the transfer and who benefits from each
• Finish with a judgement on which suits its place best and why