A Freshwater

Freshwater studies water on the land: how it moves through a drainage basin and shapes rivers, when it becomes a flood hazard, why some people have too little of it or water that is unsafe to drink, and how basins can be managed for the future. Only about 2.5% of the world’s water is fresh, and the competition for it between farms, cities, ecosystems and neighbouring states is a major source of risk and conflict.

Questions that frame the option

The option follows four lines of geographical inquiry. The first asks how physical processes control the movement of water through a basin and the landforms rivers build. The second asks how physical and human factors make flood risk greater in some places than in others, and how it can be reduced. The third asks why different actors hold such different power over the quantity and quality of water. The fourth asks which management choices, from village check dams to basin-wide plans, give the best future for a drainage basin and the people in it.

These inquiries lead to real questions that geographers try to answer with evidence:

• Why did the Netherlands record no deaths in the July 2021 rainstorm that killed more than 180 people in Germany?

• Why did the 2022 floods in the Indus basin kill 1,739 people in Pakistan, almost half of them in the flat, low province of Sindh?

• Why has coastal Louisiana lost about a quarter of its land since 1932, when the Mississippi still carries millions of tonnes of sediment to the Gulf of Mexico?

• Can Ethiopia, Sudan and Egypt share the Nile now that the Grand Ethiopian Renaissance Dam is full?

• Would the Mekong delta survive if every planned dam in the basin were built?

What the option covers

The option has four subtopics. The first two run from physical processes to a hazard; the last two run from water as a scarce resource to its management.

Several places reappear from different angles. The Mississippi is a delta losing land in the first subtopic and the source of the Gulf of Mexico’s dead zone in the third; the Aswan High Dam explains Egypt’s water supply and also the erosion of the Nile delta; the Indus is a flood case study and a basin threatened by salinisation.

How the subtopics connect

The concept map shows the main links. Water that falls on a basin follows fast or slow routes to the river, and those routes set the shape of the storm hydrograph, so the processes of the first subtopic explain the flood risk of the second. Aquifers, lakes and wetlands are stores in the same system, and their overuse and pollution are the subject of the third. Scarcity, pollution and conflict over shared rivers then drive the management schemes of the fourth, while dams and wetlands also hold back floodwater.

The links run in both directions across space. A decision taken upstream changes conditions downstream: channelisation in one town can raise flood peaks in the next, an upstream state can hold back water its neighbours depend on, and dams that trap sediment starve a delta hundreds of kilometres away. These spatial interactions between the upstream and downstream parts of a basin link all four subtopics.

Key concepts in Freshwater

The four key concepts appear on every page, together with three concepts that belong to this option in particular: systems, flood mitigation and water security.

Water security is also a core idea of the unit on global resource consumption, where water is part of the water–food–energy nexus and travels between countries as embedded water in traded food. Global climate change links the option to the unit on climate: a warmer atmosphere holds about 7% more water vapour for each 1 °C of warming, so heavier rainfall extremes raise flood risk, while higher evaporation deepens droughts. Rapid urbanisation, studied with population change, covers soil with impermeable surfaces and concentrates demand, as in Chennai in 2019. Deltas connect the option to Oceans and coastal margins, and sustainability runs through every judgment about dams, aquifers and wetlands.

How SL and HL differ

Freshwater is one of seven options. SL students choose two options and HL students choose three, so an HL student may take Freshwater alongside two others while an SL student takes it with one. The content of the option is identical at both levels: every subtopic, case study and skill is studied in the same depth, and nothing on the option’s pages is HL only.

Both levels also answer the same Paper 1 question on Freshwater, marked with the same markbands. SL and HL differ only in the number of options studied and in the HL extension units, which HL students take in addition.

Assessment

Freshwater is examined in Paper 1. For each option studied there is a structured question built on a stimulus, worth 10 marks, followed by one extended answer worth 10 marks, chosen from two. The structured question typically has four parts: (a)(i) and (a)(ii), one mark each, read a value or fact from the stimulus; (b), two marks, asks for an outline of one cause or effect; and (c), three marks plus three, asks for two developed explanations.

Freshwater stimuli are often hydrographs, flood frequency data, topographic map extracts of a river and its valley, maps of water scarcity or tables of water use. Typical short questions ask candidates to estimate a lag time or a grid reference, outline how a land use changes flood risk, or explain two causes of seasonal variation in discharge. Extended questions tend to pair one physical theme, such as the formation of landforms by erosion and deposition, with one management theme, such as the costs and benefits of dams or the effectiveness of integrated drainage basin management.