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IB Geography: Options Freshwater, oceans, extreme environments, hazards, tourism, food, urban. 7 subtopics, 35 key terms.
Learn this topic properly. Interactive diagrams, worked examples, check questions and exam-style practice with mark schemes.
Open “Options” in FortyFive → In this topic: 4.1 · 4.2 · 4.3 · 4.4 · 4.5 · 4.6 · 4.7
4.1 Option A · Freshwater: drainage basins, floods and managementKey terms Drainage basin The area drained by a river and its tributaries, bounded by a watershed. Storm hydrograph A graph of river discharge after a rainfall event. Lag time Time between peak rainfall and peak discharge. Discharge Volume of water passing a point per second (m³/s, cumecs). Aquifer Rock that stores and transmits groundwater. Basin system : inputs (precipitation), stores (interception, soil, groundwater), flows (infiltration, throughflow, overland flow, baseflow), outputs (evapotranspiration, runoff).
The full notes, worked example, interactive diagram and check questions for this subtopic are in the app.
Exam tip: Draw and annotate a hydrograph: label rising limb, peak, lag time, falling limb and baseflow.
4.2 Option B · Oceans and coastal marginsKey terms Thermohaline circulation Global ocean circulation driven by differences in temperature and salinity. El Niño–Southern Oscillation (ENSO) A periodic warming of the eastern Pacific that disrupts weather worldwide. Ocean acidification Falling ocean pH as seawater absorbs CO₂. Exclusive economic zone (EEZ) Sea area up to 200 nautical miles from the coast where a state controls resources (UNCLOS). Longshore drift Movement of sediment along a coast by waves. Currents redistribute heat: e.g. the Gulf Stream warms north-west Europe.
The full notes, worked example and check questions for this subtopic are in the app.
Exam tip: Coastal management answers need named schemes: e.g. Holderness coast (UK) or the Maldives' Hulhumalé island.
4.3 Option C · Extreme environmentsKey terms Extreme environment A place with harsh conditions: cold (polar, high altitude) or hot arid. Permafrost Ground that stays frozen for at least two years. Freeze–thaw weathering Water freezes in cracks, expands by about 9 % and breaks the rock. Desertification Land degradation in drylands caused by climate and human activity. Periglacial Cold, non-glacial environments with permafrost and freeze–thaw. Characteristics : low or unpredictable precipitation, temperature extremes, poor soils, remoteness, low population density.
The full notes, worked example and check questions for this subtopic are in the app.
Exam tip: Climate change is a key link: thawing permafrost, retreating glaciers and spreading deserts all connect to Core 2.
4.4 Option D · Geophysical hazardsKey terms Hazard A potential threat to people and property. Disaster A hazard event causing major loss of life or damage that overwhelms a community. Moment magnitude scale Measures the energy released by an earthquake (logarithmic). Volcanic Explosivity Index (VEI) A 0–8 scale of eruption size. Liquefaction Saturated ground behaving like a liquid during shaking. Plate boundaries : destructive (subduction: violent volcanoes, big earthquakes), constructive (effusive eruptions), conservative (earthquakes, e.g. San Andreas).
The full notes, worked example and check questions for this subtopic are in the app.
Exam tip: Compare contrasting case studies (rich vs poor countries) to show how vulnerability shapes outcomes.
4.5 Option E · Leisure, tourism and sportKey terms Tourism area life cycle Butler's model (1980): exploration, involvement, development, consolidation, stagnation, then decline or rejuvenation. Carrying capacity The maximum number of visitors a place can sustain without damage. Ecotourism Responsible travel that conserves the environment and benefits local people. Leakage Tourist spending that leaves the host country (e.g. to foreign hotel chains). Mega-event A large international event such as the Olympics or FIFA World Cup. Growth of tourism: rising incomes, cheap flights, more leisure time, the internet.
The full notes, worked example and check questions for this subtopic are in the app.
Exam tip: Locate case studies on Butler's curve: “Benidorm moved from stagnation to rejuvenation by…”.
4.6 Option F · Food and healthKey terms Undernutrition Too little food or nutrients. Overnutrition Too much food, leading to obesity. Epidemiological transition The shift from infectious to non-communicable diseases as countries develop (Omran, 1971). Green Revolution High-yielding crops, irrigation and fertilisers from the 1960s. Disability-adjusted life year (DALY) One lost year of healthy life. Measures : undernourishment rates, Global Hunger Index, life expectancy, DALYs, health-adjusted life expectancy.
The full notes, worked example and check questions for this subtopic are in the app.
Exam tip: Use diffusion models (contagious, hierarchical) for disease questions: they are option-specific vocabulary.
4.7 Option G · Urban environmentsKey terms Urbanisation The rise in the share of people living in urban areas. Counter-urbanisation Movement from cities to rural areas. Gentrification Wealthier people move into and upgrade a poorer area, often displacing residents. Urban heat island A city is warmer than its surroundings. Informal settlement Unplanned housing without legal tenure or full services. Over 55 % of people now live in urban areas (UN), and the share is rising, especially in Africa and Asia.
The full notes, worked example and check questions for this subtopic are in the app.
Exam tip: Pick one city you know well and learn 10 facts: it can support almost any urban essay.
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