Water scarcity (ESS HL)

Water scarcity at Higher Level: At HL, scarcity is also an economic question: economic scarcity is about money and investment, and price is one of the strongest tools for cutting demand. Your examples differ from SL: Egypt and the Nile, Pakistan, the Cauvery and Melbourne's drought.

Not enough water for the people who need it: water scarcity is the limited availability of water to human societies. It is measured by how much of the water available is already being taken out each year.

Remember it as: Taken out, divided by what is there: the bigger the share, the scarcer the water.

Reading a scarcity map: Pattern first: 'scarcity rises in many countries, most near the equator and in the mid latitudes'. Then a named country and its direction: 'Sahrel rises from 10-20% to over 40%'.

Real example: the World Resources Institute's 2023 study named the five most water-stressed countries: Bahrain, Cyprus, Kuwait, Lebanon and Oman. Like the other most-stressed countries, each uses over 80% of its renewable supply in a normal year.

A country, not a region: When asked for a country, give a country's name: 'Europe' or 'Africa' is a region and scores nothing. For a change, give the place AND whether scarcity rises or falls.

The first kind of scarcity is about nature: the water is simply not there. This is physical water scarcity.

Remember it as: Physical: the water is not there.

Real example: Egypt gets almost no rain, so about 97% of its water comes from one river, the Nile, which rises in other countries. Every extra person shares the same river.

People can make it worse: Physical scarcity is not only climate. A river that is over-used, so it no longer reaches the sea, is physically scarce because of people.

The second kind is about money and building. The water is there, but the infrastructure is not. This is economic water scarcity.

Remember it as: Physical: no water. Economic: no pipes.

Real example: the Blue Nile rises at Lake Tana in Ethiopia, and the country has many rivers. Yet many rural families still walk to rivers and springs to collect water, because there are too few wells, pipes and treatment works.

High rainfall is not the same as no scarcity: A country with heavy rain can still be short of water. If people cannot store it, move it or make it safe, that is economic scarcity.

Scarcity gets worse when demand rises or the usable supply falls. Each factor below is a change, and climate change is one of them.

Remember it as: More people, richer diets, thirstier farms, a hotter climate.

Real example: Lake Urmia, in north-west Iran, was one of the largest salt lakes in the world. It lost most of its water from the 1990s to the 2010s, as dams and wells took water for farms and droughts struck.

It must be a change: 'The area has a dry season' or 'it has low rainfall' does not explain an INCREASE in stress. Say what changes: 'less rain because of global warming'. For climate change, name the change AND its effect on water.

Both farms and growing cities make water scarcer. They change how much water there is (its availability) and how clean it is (its quality). A dirty river is water people cannot use.

Remember it as: Farms drink most; cities dirty most; both can do better.

Real example: in Australia's Murray-Darling Basin, most of the water taken from the rivers irrigates rice, cotton and fruit. In 1991 a toxic algal bloom about 1,000 km long spread along the Darling River, and towns downstream depend on the same water.

Weigh both, both ways: In a 'which does more harm' essay, give farms AND cities, quality AND availability, harm AND the fixes each can make. Then decide.

Population growth affects water at two scales: local (a town, a lake, an aquifer) and regional (a whole river basin or country). Most effects are harmful; one can help.

Remember it as: More mouths, more fields, more factories, less water left.

Real example: Pakistan's population grew from under 40 million in 1950 to about 240 million in 2023. Most of its water comes from the Indus and its tributaries, through one of the world's largest irrigation systems. Farms and cities now pump so much groundwater that water tables are falling, for example around Lahore.

Do not forget the good news: Growing demand can push people to invent and save: recycling, drip irrigation, better management. One point in a [7] can be a positive effect.

When water is scarce, its users compete for it. A conflict over water is a dispute between two users who want the same water.

Real example: the Cauvery (Kaveri) River rises in Karnataka and flows into Tamil Nadu, India. The two states have argued over its water for over a century: in the 2016 drought, protests broke out in Bengaluru after a court ordered Karnataka to release water downstream.

A supply problem is not a conflict: 'Less snow is falling' or 'the pumps need electricity' are problems of supply. A conflict needs two sides: 'farmers who irrigate v the city that needs drinking water'.

There are two ways to fight scarcity: change how people use and value water, or build technology that makes more water or wastes less. Desalination often uses reverse osmosis and leaves salty waste, brine.

Real example: in the Millennium Drought (about 1997-2009), Melbourne asked people to use no more than 155 litres each a day (Target 155), with rules on garden watering, and use fell sharply. It also built the Wonthaggi desalination plant for several billion dollars; it was finished in 2012, after the rains returned, and first supplied water in 2017.

A conclusion that scores: 'Technology is needed where scarcity is severe, but changing behaviour tackles the root cause and is affordable everywhere, so the two work best together.' Back it with your named examples.