1. MASTER CHAIN FORMULA FOR PAPER 2

Use this for almost every 3–6 mark answer:

• Cause

• Process

• Immediate effect

• Final consequence

• Case-study link

Template:

• ______ causes ______.

• This leads to ______.

• As a result, ______.

• In this location, this is important because ______.

Example:

• Urbanisation increases the number of people in towns.

• This increases demand for water.

• More groundwater is extracted.

• As a result, aquifers may be depleted.

• In hot dry areas, this is worse because rainfall is limited.

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2. POPULATION GROWTH CHAINS

Chain: High birth rate → population growth

• High birth rate means more babies are born.

• More children survive if healthcare improves.

• Total population increases.

• Demand for food, water, housing and jobs rises.

• Pressure on natural resources increases.

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Chain: Falling death rate → population growth

• Improved healthcare reduces deaths from disease.

• Better sanitation and clean water reduce infections.

• More people survive to older ages.

• Population increases.

• More resources are needed to support the larger population.

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Chain: Population growth → pressure on food supply

• Population increases.

• More food is needed.

• Farmers may grow crops more intensively.

• More fertilisers, pesticides and irrigation may be used.

• Soil, water and ecosystems may be damaged.

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Chain: Population growth → water shortage

• More people need water for drinking, washing and cooking.

• More water is also needed for farming and industry.

• Groundwater and rivers are extracted faster.

• Water supply may not recharge quickly enough.

• Shortages occur.

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Chain: Population growth → waste problem

• More people produce more solid waste and sewage.

• Waste collection systems may become overloaded.

• Waste may be dumped illegally.

• Land and water pollution increase.

• Disease risk may rise.

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Chain: Population growth → deforestation

• More land is needed for housing, farming and fuelwood.

• Forests are cleared.

• Habitats are destroyed.

• Biodiversity decreases.

• Soil erosion and carbon dioxide levels increase.

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Chain: Population growth → unemployment

• Population grows faster than job creation.

• More people compete for limited jobs.

• Unemployment rises.

• Poverty may increase.

• People may migrate to find work.

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3. POPULATION DENSITY CHAINS

Chain: High population density → pressure on services

• Many people live in a small area.

• Demand for schools, hospitals, transport and water increases.

• Services become overcrowded.

• Quality of life may fall.

• Government spending may need to increase.

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Chain: High population density → housing shortage

• More people need homes.

• Land becomes expensive.

• Poorer people may live in overcrowded or informal housing.

• Sanitation may be poor.

• Disease may spread more easily.

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Chain: Low population density → poor service access

• Few people live over a large area.

• It is expensive to provide roads, schools and healthcare.

• People may travel long distances for services.

• Development may be slower.

• Migration to towns may increase.

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4. POPULATION DISTRIBUTION CHAINS

Chain: Flat fertile land → dense population

• Flat land is easier to build on.

• Fertile soil supports farming.

• Food and jobs are available.

• Transport routes are easier to build.

• More people settle there.

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Chain: Coastal location → dense population

• Coastal areas provide fishing opportunities.

• Ports allow trade and transport.

• Tourism may develop.

• Jobs increase.

• Settlements grow near the coast.

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Chain: River valley → dense population

• Rivers provide water for drinking and irrigation.

• Floodplains may have fertile soil.

• Transport and trade may be easier.

• Agriculture and settlements develop.

• Population density increases.

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Chain: Mountains → sparse population

• Steep slopes make farming difficult.

• Transport routes are harder to build.

• Landslides may occur.

• Building costs are high.

• Fewer people settle there.

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Chain: Desert → sparse population

• Rainfall is low.

• Water supply is limited.

• Crop growth is difficult.

• Few jobs are available outside mining or tourism.

• Population remains low.

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Chain: Ice-covered land → sparse population

• Ice prevents farming and construction.

• Temperatures are extremely low.

• Transport is difficult.

• Food and fuel must be imported.

• Permanent settlement is limited.

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5. MIGRATION CHAINS

Chain: Push factors → emigration

• People face problems in their home area.

• Examples:

  • unemployment

  • poor education

  • poor healthcare

  • war/conflict

  • natural hazards

  • harsh climate

• People leave to improve their quality of life.

• Population in the origin area may decrease.

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Chain: Pull factors → immigration

• Another area offers better opportunities.

• Examples:

  • jobs

  • universities

  • healthcare

  • safer living conditions

  • higher wages

• People move there.

• Population in the destination area increases.

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Chain: Young adults migrate → ageing population left behind

• Young adults leave rural/remote areas.

• Older people remain.

• Birth rate may fall because fewer young adults have children there.

• Working-age population decreases.

• Healthcare and elderly care pressure increases.

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Chain: Migration to cities → urbanisation

• People move from rural areas to cities for jobs and education.

• City population increases.

• Housing demand increases.

• Informal settlements may grow.

• Water, waste and transport systems become pressured.

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Chain: Out-migration → labour shortage

• Working-age people leave.

• Fewer workers remain for farming, fishing or industry.

• Production may decrease.

• Local businesses may struggle.

• Economy may decline.

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Chain: Out-migration → remittances

• Migrants work in another region/country.

• They send money back home.

• Families can afford food, education and healthcare.

• Local living standards may improve.

• However, the local area may still lose skilled workers.

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6. URBANISATION CHAINS

Chain: Urbanisation → groundwater shortage

• Urban population increases.

• More water is needed for homes, industry and services.

• More groundwater is pumped from aquifers.

• Concrete and tarmac reduce infiltration.

• Groundwater is used faster than it is replaced.

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Chain: Urbanisation → flooding

• Vegetation is removed for buildings and roads.

• Concrete surfaces are impermeable.

• Rainwater cannot infiltrate into soil.

• Surface runoff increases.

• Drains and rivers may overflow.

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Chain: Urbanisation → air pollution

• More cars, buses and industries operate in cities.

• Fossil fuels are burned.

• Pollutants such as carbon monoxide, particulates and nitrogen oxides are released.

• Air quality decreases.

• Respiratory disease may increase.

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Chain: Urbanisation → waste pollution

• More people produce more waste.

• Waste systems may not cope.

• Waste may be dumped into rivers or open land.

• Water and land pollution increase.

• Disease vectors such as rats and flies may increase.

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Chain: Urbanisation → loss of farmland

• Cities expand outwards.

• Farmland is converted into housing, roads and factories.

• Local food production decreases.

• Food may need to be imported.

• Food prices may rise.

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Chain: Urbanisation → heat island effect

• Concrete and asphalt absorb heat.

• Fewer trees are present to provide shade and transpiration.

• Vehicles and buildings release heat.

• City temperatures become higher than surrounding rural areas.

• Energy demand for cooling increases.

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7. AGRICULTURE AND YIELD CHAINS

Chain: Irrigation → increased yield

• Irrigation provides water when rainfall is low.

• Plants can photosynthesise more.

• Growth improves.

• Crop yield increases.

• Food supply and farmer income may rise.

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Chain: Fertilisers → increased yield

• Fertilisers add mineral ions such as nitrates, phosphates and potassium.

• Plants make proteins and grow faster.

• More leaves/flowers/fruits may form.

• Crop yield increases.

• Farmer income may improve.

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Chain: Pesticides → increased yield

• Pesticides kill insects, fungi or weeds.

• Less crop damage occurs.

• More crops survive until harvest.

• Yield increases.

• Food supply and profit may increase.

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Chain: Mechanisation → increased yield

• Machines plough, plant and harvest faster.

• Larger areas can be farmed.

• Harvesting can happen at the best time.

• Crop loss may decrease.

• Total production increases.

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Chain: Improved seeds → increased yield

• Improved varieties may resist disease or drought.

• More plants survive.

• Growth is more reliable.

• Yield increases.

• Farmers earn more income.

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Chain: Greenhouses → increased yield

• Temperature, water and pests can be controlled.

• Plants grow in better conditions.

• Growing season may be extended.

• More crops can be produced each year.

• Yield increases.

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Chain: Crop rotation → soil fertility maintained

• Different crops are grown in different seasons.

• Nutrient depletion is reduced.

• Legumes may add nitrates to soil.

• Soil remains fertile.

• Yield is maintained over time.

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Chain: Terracing → farming on slopes

• Terraces create flat steps on hillsides.

• Water runoff slows down.

• Soil erosion decreases.

• Crops can grow on steep land.

• Agricultural land area increases.

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8. AGRICULTURE ENVIRONMENTAL DAMAGE CHAINS

Chain: Over-irrigation → salinisation

• Irrigation water contains dissolved salts.

• In hot climates, water evaporates from soil.

• Salts are left behind.

• Soil becomes too salty.

• Crop growth decreases.

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Chain: Over-irrigation → water shortage

• Large amounts of water are taken from rivers or aquifers.

• Less water remains for people, wildlife and other farms.

• Rivers may shrink and groundwater levels fall.

• Ecosystems may be damaged.

• Conflict over water may increase.

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Chain: Fertiliser use → eutrophication

• Fertilisers are washed into rivers by runoff.

• Nitrates and phosphates increase.

• Algae grow rapidly.

• Dead algae are decomposed by bacteria.

• Oxygen is used up.

• Fish and aquatic organisms die.

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Chain: Pesticides → non-target species death

• Pesticides are sprayed on crops.

• They may kill useful insects such as bees.

• Pollination decreases.

• Biodiversity decreases.

• Crop production may eventually suffer.

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Chain: Pesticides → bioaccumulation

• Pesticides enter the bodies of organisms.

• They are not broken down easily.

• Concentration builds up in tissues.

• Predators eat many contaminated prey.

• Higher trophic levels suffer poisoning.

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Chain: Monoculture → disease risk

• One crop species is grown over a large area.

• All plants have similar weaknesses.

• Disease or pests spread quickly.

• Large areas of crop may fail.

• Food supply and income decrease.

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Chain: Intensive farming → soil degradation

• Land is used continuously.

• Nutrients are removed faster than replaced.

• Soil structure may be damaged by machinery.

• Fertility decreases.

• Yield falls over time.

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Chain: Overgrazing → soil erosion

• Too many animals graze in one area.

• Vegetation is removed.

• Roots no longer hold soil together.

• Wind and rain remove topsoil.

• Desertification may occur.

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9. FOOD SECURITY CHAINS

Chain: Drought → food insecurity

• Rainfall decreases.

• Crops receive less water.

• Photosynthesis and growth decrease.

• Crop yield falls.

• Food supply decreases and prices rise.

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Chain: Cash crops → food insecurity

• Farmers grow crops for sale/export instead of food crops.

• Less land is used to grow local food.

• Local food supply decreases.

• Food prices may rise.

• Poor people may not afford enough food.

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Chain: Climate change → food insecurity

• Temperatures and rainfall patterns change.

• Droughts, floods and pests may increase.

• Crops fail more often.

• Food supply becomes less reliable.

• Malnutrition risk increases.

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Chain: Conflict → food insecurity

• Farming land may be abandoned.

• Transport routes may be blocked.

• Food cannot reach markets.

• Prices rise.

• People may suffer hunger or famine.

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Chain: Soil erosion → food insecurity

• Topsoil is removed by wind or water.

• Nutrients and organic matter are lost.

• Crop growth decreases.

• Yield falls.

• Food supply becomes less reliable.

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Chain: Population growth → food insecurity

• More people need food.

• Food production may not increase fast enough.

• More imports may be needed.

• Poor families may not afford food.

• Food insecurity increases.

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10. FOOD SECURITY SOLUTION CHAINS

Chain: Irrigation → improved food security

• Irrigation supplies water during dry periods.

• Crop growth becomes more reliable.

• Yields increase.

• Food supply increases.

• Food insecurity decreases.

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Chain: Fertilisers → improved food security

• Fertilisers add nutrients to soil.

• Crop growth improves.

• More food is produced per hectare.

• Food availability increases.

• Prices may become more stable.

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Chain: Improved storage → food security

• Better storage protects crops from pests, moisture and decay.

• Less food is wasted after harvest.

• More food remains available.

• Farmers can sell crops later.

• Food security improves.

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Chain: GM / drought-resistant crops → food security

• Crops survive with less water or resist pests.

• Crop losses decrease.

• Yield becomes more reliable.

• Food supply increases.

• Farmers are less affected by drought or disease.

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Chain: Education for farmers → food security

• Farmers learn better methods.

• They use water, fertilisers and pesticides more efficiently.

• Yield increases without as much environmental damage.

• Food production becomes more sustainable.

• Food security improves.

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11. WATER SUPPLY CHAINS

Chain: Rainfall → groundwater recharge

• Rain falls on land.

• Some water infiltrates into soil.

• Water percolates into aquifers.

• Groundwater stores are replenished.

• Wells and springs can supply water.

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Chain: Drought → water shortage

• Rainfall is lower than normal.

• Rivers and reservoirs receive less water.

• Groundwater recharge decreases.

• Water supply falls.

• Restrictions or shortages may occur.

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Chain: Population growth → water demand

• More people need drinking water and sanitation.

• More food must be grown, increasing irrigation.

• More industry may develop.

• Water extraction rises.

• Shortage risk increases.

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Chain: Industry → water pollution

• Factories may release chemicals or warm water.

• Pollutants enter rivers or groundwater.

• Water quality decreases.

• Aquatic organisms may die.

• Water may become unsafe for people.

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Chain: Agriculture → water pollution

• Fertilisers, pesticides and animal waste wash into rivers.

• Nutrients and toxins enter water.

• Eutrophication or poisoning may occur.

• Fish and other organisms die.

• Drinking water treatment becomes more expensive.

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12. WATER MANAGEMENT CHAINS

Chain: Drip irrigation → water conservation

• Drip irrigation delivers water directly to plant roots.

• Less water evaporates or runs off.

• Crops still receive enough water.

• Water use becomes more efficient.

• Shortage risk decreases.

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Chain: Rainwater harvesting → water supply

• Rainwater is collected from roofs or surfaces.

• Water is stored in tanks.

• It can be used during dry periods.

• Demand for groundwater decreases.

• Water security improves.

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Chain: Fixing leaks → water conservation

• Damaged pipes lose treated water.

• Repairing leaks reduces wastage.

• More water reaches homes and farms.

• Less extra water needs to be extracted.

• Supply becomes more reliable.

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Chain: Water meters → reduced demand

• People are charged based on water use.

• They are encouraged to waste less water.

• Total consumption falls.

• Pressure on water supplies decreases.

• Water management improves.

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Chain: Desalination → increased water supply

• Seawater is treated to remove salt.

• Freshwater becomes available.

• Coastal cities can increase supply.

• However, it uses a lot of energy.

• It may be expensive and produce salty waste.

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Chain: Dams/reservoirs → water storage

• Water is stored during wet periods.

• Stored water can be used during dry periods.

• Irrigation and drinking water supply become more reliable.

• Flood risk may also be reduced.

• However, habitats may be flooded and people displaced.

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13. WATER POLLUTION CHAINS

Chain: Sewage → disease

• Untreated sewage enters rivers.

• Pathogens contaminate the water.

• People may drink or wash in unsafe water.

• Diseases such as cholera or diarrhoea spread.

• Death rates may increase.

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Chain: Sewage → oxygen depletion

• Sewage contains organic matter.

• Decomposers break it down.

• Decomposers use oxygen during respiration.

• Dissolved oxygen levels fall.

• Fish and aquatic organisms die.

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Chain: Oil spill → marine damage

• Oil spreads across the water surface.

• It coats birds’ feathers and mammals’ fur.

• Animals lose insulation or ability to fly/swim.

• Oil blocks sunlight and damages food chains.

• Marine biodiversity decreases.

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Chain: Plastic waste → microplastics

• Plastic enters rivers and oceans.

• Sunlight and waves break it into smaller pieces.

• Microplastics are eaten by fish and other organisms.

• They enter food chains.

• Wildlife and humans may be affected.

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Chain: Industrial chemicals → bioaccumulation

• Toxic chemicals enter water.

• Small organisms absorb them.

• Predators eat contaminated prey.

• Concentration increases up the food chain.

• Top predators may be poisoned.

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14. WATER TREATMENT CHAINS

Chain: Screening → cleaner water

• Large objects are removed by screens.

• Water has fewer solid materials.

• Equipment is protected from damage.

• Further treatment becomes easier.

• Water quality improves.

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Chain: Sedimentation → removal of solids

• Water is left in tanks.

• Heavy particles settle at the bottom.

• Sludge is removed.

• Water becomes clearer.

• Filtration becomes more effective.

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Chain: Filtration → removal of small particles

• Water passes through sand/gravel/filter material.

• Small suspended particles are trapped.

• Water becomes clearer.

• Some microorganisms may also be removed.

• Water quality improves.

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Chain: Chlorination → safer drinking water

• Chlorine is added to water.

• Bacteria and pathogens are killed.

• Disease risk decreases.

• Water becomes safer to drink.

• Public health improves.

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15. QUICK MODEL CHAINS FOR COMMON PAPER 2 QUESTIONS

“Explain why crop yield decreases”

• Less water / fewer nutrients / more pests.

• Photosynthesis decreases.

• Plant growth slows.

• Fewer fruits/seeds form.

• Yield falls.

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“Explain why people settle near coasts”

• Fishing and ports provide jobs.

• Transport and trade are easier.

• Tourism may develop.

• Food and income are available.

• Population grows.

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“Explain why harsh climate causes migration”

• Extreme temperatures make living conditions difficult.

• Farming may be limited.

• Jobs may be fewer.

• People seek better education, work and services elsewhere.

• Migration increases.

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“Explain why groundwater is at risk”

• Water demand increases.

• More groundwater is extracted.

• Urban surfaces reduce infiltration.

• Aquifers recharge more slowly.

• Groundwater levels fall.

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“Explain why food insecurity occurs”

• Food production decreases or demand increases.

• Supply becomes unreliable.

• Prices rise.

• Poor people cannot afford enough food.

• Hunger and malnutrition increase.