Comprehensive Study Notes: Cambridge IGCSE and O Level Geography

THEME 1: POPULATION AND SETTLEMENT

1.1 Population Dynamics

• History of World Population Growth:

  • For most of human history, the population was very low, estimated at $125,000$ people a million years ago.

  • The Neolithic Revolution ($10,000$ years ago), which involved animal domestication and crop cultivation, saw the population reach $5$ million.

  • Technological advances increased the carrying capacity (verbatim: "the largest population that the resources of a given environment can support").

  • Population reached $30$ million by $3500\,BCE$, $250$ million $2,000$ years ago, and $500$ million by $1650$.

  • The first billion was reached in $1800$.

• Time Spans for Each Billion Added:

  • 1st Billion: All of human history ($1800$)

  • 2nd Billion: $130$ years ($1930$)

  • 3rd Billion: $30$ years ($1960$)

  • 4th Billion: $14$ years ($1974$)

  • 5th Billion: $13$ years ($1987$)

  • 6th Billion: $12$ years ($1999$)

  • 7th Billion: $12$ years ($2011$)

  • 8th Billion: Estimated for $2023$.

• Causes of Population Change:

  • Birth Rate: Number of births per $1,000$ population per year.

  • Death Rate: Number of deaths per $1,000$ population per year.

  • Natural Change: The difference between the birth rate and death rate ($BR - DR$). If positive, it is natural increase; if negative, it is natural decrease.

  • Migration: The balance between immigration and emigration.

  • Net Migration Rate: The difference between immigration and emigration rates.

• The Demographic Transition Model (DTM):

  • Stage 1 (High Stationary): High, stable birth rates; high, fluctuating death rates (famine, disease). Low life expectancy and high infant mortality. Pre-industrial society.

  • Stage 2 (Early Expanding): Death rate declines rapidly due to better nutrition, health, and medicine. Birth rate remains high. Significant natural increase. Example: Niger.

  • Stage 3 (Late Expanding): Birth rate begins to fall as social norms adjust to lower mortality. Urbanization slows. Example: Bangladesh.

  • Stage 4 (Low Stationary): Both rates are low. Population growth is slow. Example: UK.

  • Stage 5 (Natural Decrease): Birth rate falls below the death rate. Death rate increases slightly due to an aging population. Example: Japan, Germany.

• Total Fertility Rate (TFR): The average number of children a woman has during her lifetime.

  • Highest rates in $2016$: Niger ($7.6$), South Sudan ($6.7$), D.R. Congo ($6.5$).

  • Lowest rates in $2016$: South Korea ($1.2$), Romania ($1.2$), Singapore ($1.2$), Taiwan ($1.2$).

• Factors Affecting Fertility:

  • Demographic: High infant mortality (deaths under $1$ year per $1,000$ live births) leads to families having more children to compensate.

  • Social/Cultural: Traditions, religious opposition to birth control (Muslim/Roman Catholic), and female literacy. Education is negatively correlated with TFR.

  • Economic: In least developed countries, children are economic assets (labor/old age care). In developed countries, the cost of dependent years is high.

  • Political: Pro-natalist policies (France) vs. Anti-natalist policies (China’s one-child policy).

• Factors Affecting Mortality:

  • Average life expectancy at birth: Currently $72$ years ($70$ for men, $74$ for women).

  • Causes of death in rich vs. poor countries (WHO Q&A):

    • High-income countries: $50\%$  of deaths are adults over $80$. Leading causes: Chronic diseases (cardiovascular, cancer, dementia).

    • Low-income countries: $40\%$  of deaths are children under $14$. Leading causes: Infectious diseases (HIV/AIDS, respiratory infections, tuberculosis, malaria, diarrhea) and birth complications.

• Case Study: Kenya (High Growth):

  • Population increased from $10.9$ million ($1969$) to over $45$ million ($2016$).

  • Youth dependency: $42\%$  of the population is under $15$.

  • Issues: Pressure on land, high youth unemployment, and overcrowding in Kibera (Nairobi’s largest slum).

• Case Study: Russia (Population Decline):

  • Population reached peak at $148.7$ million in $1991$; decreased to $144.3$ million in $2016$.

  • Causes: Low birth rates, high male death rates (alcohol, smoking, poverty), and emigration.

  • Policies: "Paternal Glory" medals for families with $4+$ children.

• Case Study: Bangladesh (Overpopulation):

  • Density: $1,128$ people per $km^2$ ($20$ times world average).

  • Issues: Lack of cultivable land ($8,000\,ha$ lost annually to urban sprawl), regular flooding ($40\%$  of land), underemployment ($40\%$ ).

• Case Study: Australia (Underpopulation):

  • Density: $3$ per $km^2$.

  • Resources: Coal, iron, copper, gold, uranium.

  • Policies: Positive net migration ($+9/1,000$) to develop resources and solve skill shortages.

• Population Policies:

  • China (Anti-natalist): Introduce in $1979$ to reach an optimum population of $700$ million by $2080$. Impact: Gender imbalance ($119$ boys to $100$ girls) and "four-two-one" problem. Policy relaxed in $2016$ to two children.

  • France (Pro-natalist): "Code de la Famille" ($1939$). Current measures: $3$ year maternity leave, near full pay; higher child benefits for third child; $30\%$  reduction on public transport for large families.

1.2 Migration

• Definition: Movement across a boundary to establish a new permanent residence (defined by UN as > $1$ year).

• Push Factors: Negative conditions at origin (unemployment, intolerance, famine).

• Pull Factors: Positive conditions at destination (high wages, wide amenities, tolerance).

• Types of Migration:

  • Voluntary: Choice-based (higher salaries, retirement).

  • Involuntary (Forced): Religious persecution, slavery, natural disasters, conflict.

  • Refugees: People forced to flee international borders.

  • Internally Displaced People (IDPs): Forced to move but staying within their country.

• Impact of Migration:

  • Origin: Remittances (Global flow $2016$: $575$ billion). Brain drain (loss of skilled workers). Aging population.

  • Destination: Increased labor supply, lower inflation, cultural diversity. Pressure on housing/services.

• Case Study: Mexico to USA:

  • Largest immigrant community in the world ($12$ million Mexican-born in USA).

  • Migration driven by income gap and high unemployment in Mexico.

  • Controversy: Federation for American Immigration Reform (FAIR) vs. advocates citing labor contributions.

1.3 Population Structure

• Population Pyramids: Bar graphs showing age (y-axis) and sex (x-axis).

• Sections:

  1. Young dependent population ($0-14$).

  2. Economically active population ($15-64$).

  3. Elderly dependent population ($65+$).

• Dependency Ratio Formula:

  • $\text{Dependency Ratio} = \frac{\% \text{aged } 0-14 + \% \text{aged } 65+}{\% \text{aged } 15-64} \times 100$

• Comparison ($2016$):

  • Niger: Dependency ratio $113$; GNI per capita $950$.

  • Japan: Dependency ratio $67$; GNI per capita $38,870$.

1.4 Population Density and Distribution

• Density: Average number of people per $km^2$. World average ($2016$): $53$.

  • Asia: $136\,per\,km^2$.

  • Oceania: $5\,per\,km^2$.

• Factors Leading to Sparsity: Low temperatures (Arctic), aridity (deserts), high relief (mountains), low soil fertility, poor communications.

• Factors Leading to Density: Moderate climate, rich soil, flat land, resource availability (Ruhr coalfield), good infrastructure, coastal location.

• Case Study: North America:

  • Sparse: Canadian Northlands (permafrost, January temp < $-20^{\circ}C$).

  • Dense: Northeast USA ("Boswash"). Global cities (New York).

1.5 Settlements and Service Provision

• Patterns:

  • Dispersed: Scattered individual houses (Australian outback, Sahel).

  • Nucleated: Tightly clustered around a central feature (church, crossroads).

  • Linear: Buildings along a geological feature (river valley) or road.

• Site and Situation:

  • Site: Actual land built upon. Factors: Water supply (wet point vs. dry point), fuel, defense, building materials.

  • Situation: Settlement in relation to its surroundings.

• Hierarchy:

  • Low-order: Small settlements (hamlets, villages) with convenience goods (bread, milk). Small range (distance people travel) and threshold (minimum people needed to support the shop).

  • High-order: Large settlements (cities) with specialist goods. Large range and threshold.

  • Sphere of Influence: The area served by a settlement.

1.6 Urban Settlements

• Urban Land Use Models:

  • Burgess (Concentric Zone): Central CBD, surrounded by transition zone, then low-class, medium-class, and high-class residential rings.

  • Hoyt (Sector): Land use develops in sectors along transport routes.

  • Latin American City: Focused on a CBD with a spine and commercial axis, elite residents near the center, squatter settlements on the periphery.

• Gentrification: Renewal of run-down inner-city areas (e.g., Woodstock, Cape Town). Displaces original poor residents to camps like Blikkiesdorp ("Tin Can Town").

• Case Study: New York City:

  • Commercial area takes < $4\%$  of land but has $3.6$ million jobs.

  • Residential: $25\%$  area is open space. Staten Island has the most vacant land.

• Urban Problems:

  • Pollution: Air (motor vehicles), noise, water (China's frozen rivers, Bellandur Lake froth), and light.

  • Inequality: Measured by the Lorenz Curve. In Brazil, top $10\%$  of households possess $40\%$  of wealth.

  • Detroit (Decline): Bankrupt in $2013$. Long-term debt $18$ billion. High funztonally illiterate population ($50\%$ ).

1.7 Urbanisation

• Definition: Increase in the percentage of a population living in urban areas.

• Megacity: Population > $10$ million. In $1950$ there were only two: Tokyo and New York.

• Slum/Squatter Household (UN definition): Lacks one of five amenities:

  1. Durable housing.

  2. Sufficient living space (no more than $3$ per room).

  3. Access to improved water.

  4. Improved sanitation.

  5. Secure tenure.

• Case Study: Rio de Janeiro:

  • Four types of slum: Favelas, illegal subdivisions, invasions, and corticos (old decaying rentals).

  • Favela Bairro Project ($1994$): Upgrading with paved roads, drainage, crèches, and credit for labor.

• Sustainable Management (Curitiba, Brazil):

  • Integrated transport based on express bus lanes.

  • Cost-effective: Subway cost $80\,million\,per\,km$ vs. Busway $200,000\,per\,km$.

• Case Study: Shanghai (Economic Change):

  • Largest construction site in the world.

  • Pudong New Area created in $1990$.

  • MAGLEV train: connects Pudong to center at $431\,km/h$.

  • Master Plan ($2000-2020$): Building new eco-cities like Dongtan.

THEME 2: THE NATURAL ENVIRONMENT

2.1 Earthquakes and Volcanoes

• Volcanoes:

  • Shield: Gently sloping, hot runny lava (constructive boundaries/hotspots).

  • Composite/Cone: Steep layers of ash and sticky lava (destructive boundaries).

  • Active: Erupted recently. Dormant: Not erupted for centuries. Extinct: Not expected to erupt again.

  • Direct Hazards: Pyroclastic flows ($700^{\circ}C$), volcanic bombs, lava flows, gases.

  • Indirect Hazards: Lahars (mudflows), landslides, tsunamis.

• Earthquakes:

  • Focus: Subsurface place where earthquake starts.

  • Epicentre: Surface point directly above the focus.

  • Richter Scale: Logarithmic scale ($1$ to $10$) measuring magnitude (force). An increase of $1.0$ is $10$ times stronger.

  • Mercalli Scale: Descriptive scale ($I$ to $XII$) based on observations and damage.

• Plate Tectonics:

  • Constructive (Divergent): Plates move apart; new crust forms (Mid-Atlantic Ridge).

  • Destructive (Subduction): Oceanic plate sinks beneath continental plate; creating trenches and volcanoes (Nazca/South American plate).

  • Collision: Two continental plates collide; fold mountains form (Himalayas).

  • Conservative (Transform): Plates slide past each other (San Andreas Fault).

• Case Study: Montserrat ($1995-1997$):

  • Soufrière Hills volcano. Plymouth capital buried in ash. Population fell from $11,000$ to $4,500$.

• Case Study: Christchurch ($2010-2012$):

  • $2010$: Magnitude $7.1$. $2011$: Magnitude $6.3$.

  • $185$ deaths in $2011$ because it happened at lunchtime and was shallower ($5\,km$).

• Case Study: Nepal ($2015$):

  • Magnitude $7.8$. $9,000$ deaths. Economic cost $7$ billion ($35\%$  of GDP).

2.2 Rivers

• Hydrological Cycle Components:

  • Input: Precipitation.

  • Outputs: Evapotranspiration (EVT), Runoff.

  • Stores: Interception (vegetation), Surface storage, Soil moisture, Groundwater.

  • Processes: Stemflow, Throughfall, Infiltration, Throughflow, Percolation.

• Formulae:

  • Discharge ($Q$) = $velocity \times cross-sectional area$. Expressed in cubic metres per second ($m^3/s$ or cumecs).

  • Hydraulic Radius = $Cross-sectional area / Wetted perimeter$. Higher radius = higher efficiency.

• River Processes:

  • Erosion: Abrasion (corrasion), Attrition, Hydraulic Action, Solution (corrosion).

  • Transport: Suspension (fine particles), Saltation (bouncing), Solution (dissolved), Traction (rolling).

• River Landforms:

  • Upper Course: V-shaped valleys, potholes, waterfalls, rapids, gorges.

  • Middle Course: Meanders (erosion on outer bank, deposition on slip-off slope). Oxbow lakes.

  • Lower Course: Floodplains, Levées (raised banks), Deltas (Rhône, Nile).

• Case Study: Floods & Management:

  • Three Gorges Dam, China: World's largest HEP dam ($22,500\,MW$). Cost $25$ billion. $1.25$ million people relocated.

  • Kissimmee River, Florida: Restoration back to natural meandering state after channelization ($1960s$) caused habitat loss. Cost $980$ million.

  • Nile Delta: Subsidence and sea level rise. $1\,m$ rise would flood $20\%$  of the delta.

2.3 Coasts

• Waves:

  • Constructive: Swash > Backwash. Build up beach.

  • Destructive: Backwash > Swash. High frequency ($10–12/min$). Erode beach.

• Processes:

  • Longshore Drift: Directional movement of sediment along the shore due to oblique wave approach.

  • Wave Refraction: Bending of wave fronts as they touch the seabed.

• Erosional Landforms: Caves -> Arches -> Stacks -> Stumps. Wave-cut platforms.

• Depositional Landforms: Spits (Walvis Bay), Bars, Tombolos (Palisadoes, Jamaica), Sand Dunes (Studland).

• Coral Reefs: Require warm water ($>20^{\circ}C$), sunlight, clear water. Fringing, Barrier, and Atoll reefs. Great Barrier Reef ($2,300\,km$ long).

• Mangroves: Salt-tolerant forests. Spawning grounds for fish. Protect against storm surges.

• Case Study: Typhoon Haiyan ($2013$):

  • Winds up to $315\,km/h$. Storm surge over $6\,m$ in Tacloban. Economic cost $15$ billion.

• Management Strategies:

  • Hard Engineering: Sea walls, revetments, gabions, groynes, rock armour.

  • Soft Engineering: Beach nourishment, managed retreat, dune restoration.

2.4 Weather

• Instruments:

  • Stevenson Screen: Wooden slats, white paint, $120\,cm$ high to measure shade temperature.

  • Maximum-minimum thermometer (Six’s): Mercury/alcohol to record daily temperatures.

  • Rain gauge: Funnel and jar sunken $30\,cm$ into the ground.

  • Barometer: Measures air pressure (mb).

  • Wind Vane: Measures direction. Anemometer: Measures speed ($km/h$).

  • Hygrometer: Wet- and dry-bulb thermometer for relative humidity.

  • Sunshine Recorder: Campbell-Stokes glass sphere burns card.

• Cloud Classification:

  • High: Cirrus, Cirrocumulus.

  • Medium: Altocumulus, Altostratus.

  • Low: Stratus, Cumulus, Cumulonimbus (thunder/rain).

  • Measured in oktas (eighths).

2.5 Climate and Natural Vegetation

• Equatorial (TRF): Hot/Wet year-round ($>2,000\,mm$ rain, avg temp $27^{\circ}C$). High humidity.

  • Vegetation: Emergent trees ($45\,m$), canopy layers, buttress roots, drip-tips, lianas.

  • Nutrient Cycle: Fast decomposition but infertile soil (nutrients held in biomass).

  • Brazil Trends: Deforestation caused by cattle ranching, soybean farming, and the Trans-Amazonian Highway.

• Hot Deserts: Arid ($<250\,mm$ rain). High diurnal temperature range.

  • Vegetation (Xerophytes): Thick waxy cuticles, spines (no leaves), deep roots (phreatophytes), succulents (cactus).

  • Animal adaptations: Fennec Fox (large ears), Kangaroo Rat (efficient kidneys).

THEME 3: ECONOMIC DEVELOPMENT

3.1 Indicators of Development

• Economic Measures: GDP/GNI per capita ($\text{PPP\$}$ takes account of cost of living).

• Human Development Index (HDI): Verbatim components:

  1. Life expectancy at birth.

  2. Mean years of schooling (adults).

  3. Expected years of schooling (children).

  4. GNI per capita.

• Economic Sectors:

  • Primary: Extraction (farming, mining).

  • Secondary: Manufacturing/Processing.

  • Tertiary: Services (retail, tourism, nursing).

  • Quaternary: High-tech/R&D (IT, biotechnology, aerospace).

• Globalisation: TNCs drive change.

  • Case Study: Tata Group: Indian TNC with $660,000$ employees. Owns Tetley (UK) and Jaguar Land Rover ($2.5\,billion$ in $2008$).

3.2 Food Production

• Systems: Inputs (Land, capital, seed, livestock) -> Processes (Ploughing, weeding) -> Outputs (Yield, profit, waste).

• Green Revolution: High Yielding Varieties (HYVs).

  • Advantages: 2-4x higher yields, shorter growing season.

  • Disadvantages: High fertilizer/pesticide costs, salinisation, loss of traditional varieties.

3.3 Industry

• Location Factors: Raw materials (bulky/heavy), market, labor (skilled/low cost), power, site (flat land).

• Case Study: Bangalore, India: "Silicon Valley of India." $2,200$ ICT companies. Benefits: Skilled English-speaking workforce; lower labor costs; state government support.

3.4-3.7 Energy, Water, and Environment

• Energy: Fossils (Oil $37\%$, Coal $17\%$, Natural Gas $31\%$). Nuclear ($8\%$). Renewables (Solar, Wind, HEP).

  • Fuelwood: $2.5$ billion people rely on it. Major cause of indoor air pollution.

• Water:

  • Physical Scarcity: Demand > supply (Egypt).

  • Economic Scarcity: Limited investment/money (Sub-Saharan Africa).

  • Case Study: Colorado River: $30$ million people. Hoover Dam. Central Arizona Project ($570\,km$ canal).

• Global Warming: Enhanced Greenhouse effect due to $CO_2$, Methane, Nitrous Oxides.

• Acid Deposition: Rain with $pH < 5$. Caused by $SO_2$ and $NO_X$. Damaged forests/lakes (Angkor Wat).

THEME 4: GEOGRAPHICAL SKILLS

• Sampling:

  1. Random: Each point has equal probability (random numbers).

  2. Systematic: Regular intervals (every $100\,m$).

  3. Stratified: Proportional to groups (sampling per area percentage).

• Techniques: Choropleth maps, Isolines (join equal dots), Pie charts, Triangular graphs (Soil texture/Sectors), Kite diagrams (Vegetation).

• Route to Enquiry: Identification -> Data Collection -> Presentation -> Analysis -> Conclusion -> Evaluation.