Notes for Hazardous Environment
Natural hazards:
- Extreme events or conditions in the natural environment causing harm to people, properties, or livelihoods. Natural hazards only lead to natural disasters because people live in hazardous areas.
Types of natural Hazards:
| Tectonic and geological | Climate and meteorological |
| Earthquakes | Tropical Cyclones |
| Volcanoes | Drought |
| Tsunamis | Floods |
| Landslides | Tornadoes |
Measurements for hazards + disasters:
Magnitude: Size of the event, e.g., size of an earthquake on the Moment Magnitude Scale.
Frequency: How often an event of a certain size occurs, sometimes called the recurrence interval – the larger the event, the less frequently it occurs. However, it is the very large events that do most of the damage (to the physical environment, to people, properties, and livelihoods).
Regularity: Some hazards, such as tropical cyclones, are regular, whereas others, such as earthquakes and volcanoes are much more random.
Areal extent: The size of the area covered by the hazard.
Spatial concentration / dispersion: Distribution of hazards over space, whether they are concentrated in certain areas, such as tectonic plate boundaries, coastal location, valleys and so on.
Speed of onset: Varies from very rapid events, such as an earthquake to slower time scale events such as tropical cyclones over a period of many days.
Tropical Cyclones:
Intense, low-pressure systems that bring heavy rainfall, strong winds and high waves.
Cause other hazards such as flooding and mudslides.
Large-scale features with a diameter of up to 800 km and a calm central area, the eye.
Mainly take place in tropical / subtropical regions.
Earthquakes:
- Sudden, violent shaking of the Earth’s surface.
- Occurs after a build-up of pressure causes rocks and other materials to give way.
- Most of this pressure occurs at plate boundaries when one plate is moving against another.
- The focus refers to the place beneath the ground and is the exact position where an earthquake takes place
- The epicentre is the point on the ground surface immediately above the focus.
Measurement (Earthquakes):
- Richter scale
- Measures the energy being released by an earthquake.
- Energy is measured by a seismograph
- The scale is logarithmic, so an earthquake of 5.0 on the Richter scale is 10 times more powerful than a 4.0 one and 100 times more powerful than a 3.0.
- Moment Magnitude Scale (M)
- Measures the amount of energy released by observing the rock movement along a
fault or a fracture and produces figures similar to the Richter scale. - Every increase of 1.0 on this scale, the amount of energy released increases by over
30 & ten times increase in the amplitude recorded by the seismograph. - More accurate way of measuring and comparing earthquakes.
- Measures the amount of energy released by observing the rock movement along a
- Mercalli scale
- Based on what people experience and the amount of damage done.
Volcanoes
- An opening through the Earth’s crust through which hot molten magma and ash erupted on the land as lava, ash, and cinders.
- There are 2 types of volcanoes:
- Composite volcano is a steep-sided volcano by slow moving viscous (sticky) lava.
- Shield volcano is a low angle volcano, formed by very hot, runny lava.
- Some volcanoes e.g., Hawaii volcanoes, are found in the middle of the ocean and occur at a hotspot.
Measurements (Volcanoes)
- The strength of a volcano is measured by the volcanic explosive index (VEI).
- Amount of material ejected in the explosion.
- Height of the cloud it causes.
- Amount of damage.
- Any explosion above level 5 is very large and violent.
- A VEI 8 is known as a super volcano.
Types of plate boundaries
Constructive:
2 plates are moving apart.
Magma (molten rock) rises to the crust to fill the gap that creates new crust through submarine volcanoes.
Creates shield volcanoes.
The movement of plates over the mantle creates earthquakes.
Destructive:
2 plates moving into each other (different densities).
The denser plate (oceanic) is forced beneath the less dense plate (continental).
When the plate sinks into the mantle it forms magma, the pressure of the magma forms beneath the earth’s surface.
The magma escapes through weaknesses in the rocks and rises up through a composite volcano.
As the plates move towards one another, this movement can cause earthquakes.
Collison:
If two continental plates collide, neither can sink due to similar densities.
So, the land buckles up and creates fold mountains e.g., Himalayas.
Earthquakes can occur at collision margins.
Conservative:
Plates move past each other or move side to side at different speeds.
As plates move, friction occurs, and plates become stuck.
Pressure builds up as the plates are trying to move.
When the pressure is released, it sends out huge amounts of energy causing an earthquake.
The focus tends to be very close to the Earth’s surface, so it is a lot more destructive.
Some earthquakes may be caused by human activity such as mining, building of large dams and the underground testing of bombs.
Questions
- Identify the region with the greatest number of tropical cyclones per year.
- Briefly explain the location of the world’s volcanoes.
- How much more powerful is an earthquake of magnitude 7.0 compared with one of magnitude 4.0?
Causes of tropical cyclone hazards
- They originate over oceans that have sea surface temperatures of over 27*C.
- A supply of energy (heat and moisture) is needed from the surface of the sea.
- The sea must be at its warmest (during late summer)
- They develop further away from the Equator as there is insufficient anti-clockwise rotation (Coriolis Force) there.
- Lower and upper winds need to be coming from the same direction so vertical wind shear (the change in wind speed and direction with height) is reduced.
Tropical storms bring intense rainfall and very high winds which may cause storm surge and coastal flooding, other hazards such as flooding and mudslides.
Questions
Identify the main conditions for the formation of tropical cyclones.
State the estimated wind speed and storm surge associated with a category 3 tropical cyclone.
Outline the likely damage to buildings caused by a category 5 tropical cyclone.
Volcanic hazards
Composite volcanoes (destructive):
Pyroclastic flows – Explosive clouds of superheated material (up to 700*C) that can travel at up to 500 km/hour.
Lava flows – Lava flows at hot spots e.g., Hawaii, are relatively slow moving but they can burn buildings and vegetation.
Acidification – The increased acidity of water due to sulphur emissions from volcanoes.
Climate Change – If volcanic ash mixes with water, it can create lahars or mudflows.
Lahars – Mudflows caused by the mixing of volcanic ash and water.
There are a number of primary hazards and secondary hazards related to volcanic eruptions. The impacts will depend on the magnitude of the event and the population at risk.
Primary hazards
- The direct hazards associated with natural events.
Secondary hazards
- The indirect hazards associated with natural events.
| Primary hazard | Secondary hazards |
| Lava flows | Lahars (mudflows) |
| Ash fallout | Landslides |
| Pyroclastic flows | Acidification |
| Gas emissions | Climate change (global cooling) |
| Fire |
Earthquake hazards
| Primary hazard | Secondary hazards |
| Ground shaking | Ground failure and soul liquefaction |
| Building collapse | |
| Gas leaks and fires | |
| Landslides and rock falls | |
| Debris flow and mudflow | |
| Tsunamis |
- Liquefaction – The way in which soil, loose materials, and some rocks act like a liquid due to shaking during an earthquake.
Questions
- Distinguish between a lahar and a pyroclastic flow.
- Distinguish between primary and secondary hazards.
- Suggest why secondary hazards related to earthquakes kill more people than primary hazards.
Hazards have an impact on people and the environment:
Natural hazards occur only when people, livelihoods and/or property are at risk. If no one was affected, it wouldn’t be a hazard.
Why do people often live in hazardous environments?
- Some people consider that the potential advantages of living in an area outweigh the potential risks.
- Poor people have little choice in where they live, hence they live in unsafe areas.
- Steep slopes
- Floodplains
- Because they are prevented from living in better areas.
For example, deltas provide water, silt, fertile soils and the potential for trade and communications. They may also be subject to tropical cyclones.
A source of both risk and economic potential.
- Risk – The probability of a natural hazard causing harmful consequences, e.g., loss of life, injury, damage to properties, the economy and/or the environment.
Questions
State two reasons why people live in hazardous areas.
Outline why Mt Etna can be considered a hazard and a resource.
Suggest reasons why people live in areas that are subject to earthquakes.
Vulnerability to natural hazards:
The concept of vulnerability includes not only the physical effects of a natural hazard but also the status of people and property in the affected area. Several factors can increase people’s vulnerability to natural hazards.
- Vulnerability – The geographic conditions that increase the susceptibility of a community to a natural hazard.
Factors affecting vulnerability:
Economic factors
Levels of wealth and development: These influence building quality. People in high-income countries (HICs) generally have better quality housing than poorer communities in low-income countries (LICs), especially in slum areas.
Building styles and building codes: These affect the safety of buildings. Some countries have a more rigorous enforcement of building regulations, e.g. Japan.
Access to technology: People with access to ICT may have more warnings. Japan sends out text messages to warn people about tsunamis.
Insurance cover: The poor cannot afford insurance cover. To have insurance cover, buildings need to be made hazard resistant.
Social factors
Education: People with a better education generally have a higher income and can afford better quality housing.
Gender: Many women are carers for their children and/or their parents and they may feel responsible for them following an event.
Population density: Many rapidly growing cities and large urban areas are especially vulnerable to natural hazards.
Age: Elderly people and some with disabilities may be far less mobile than younger populations.
Physical factors
Physical geography: Some areas experience more natural hazards, e.g., along fault lines, near volcanoes and risk of hurricanes in tropical regions.
Natural environment: Some areas, e.g., steep slopes and flat, coastal lowlands, are vulnerable to natural hazards.
Questions
Briefly explain why some people are more vulnerable to hazards than others.
Outline the main impact of natural hazards on income groups.
Explain why natural hazards vary from place to place.
Short-term and long term-impacts
Nepal earthquake, 2015
Short-term impacts
In 2015 there was a 7.8 magnitude earthquake in Nepal.
There were over 300 aftershocks, some of them reaching magnitudes of over 7.0.
The main earthquake was a shallow-focus earthquake just 80 km from Kathmandu.
Rapid population growth in Kathmandu had increased the vulnerability of the area to earthquakes.
Nearly 9000 people were killed and 20,000 injured.
Overall, 8 million people were affected.
Over 600,000 homes were destroyed and over 250,000 homes were damaged.
Water and electricity were not available in many places following the earthquake.
The government immediately began to search for people in collapsed buildings.
Temporary shelters were provided for those made homeless.
Temporary schools made of bamboo and tarpaulin opened after a month.
Long-term impacts
Longer-term impacts largely related to rebuilding housing.
- One year after the earthquake, towns, and villages outside of Kathmandu remained severely damaged with debris present.
- Two years after the earthquake, only 5% of homes had been rebuilt and many school buildings were still only temporary structures.
Volcanic eruptions in Montserrat
Montserrat is a small island in the Caribbean and was affected by volcanic activity between 1995 and 2013.
Short-term impacts
In 1997 a pyroclastic flow killed 19 people.
The largest settlement, Plymouth, with a population of just 4000, was covered in ash and abandoned.
Other short-term impacts included evacuation and increased unemployment.
Long-term impacts
Long-term impacts have included the establishment of an exclusion zone, the creation of the Montserrat Volcano Observatory and the development of new infrastructure and buildings in the north of the island, including homes, hospitals, roads and expansion to the island’s ports.
Although there was an economic boom in the early 2000s, once those buildings were built many of the jobs disappeared.
Thus, with fewer jobs in construction, a declining tourist sector and rising prices, many Montserratians left the island for a second time.
Hurricane Matthew, September-October 2016
Hurricane Matthew was a Category 5 hurricane that caused significant loss of life and damage in Haiti, as well as widespread damage in parts of the USA.
The most significant impacts were felt in Haiti.
Short term impacts
Flooding, high winds, telecommunications were disrupted and damage to over 75% of Jeremie, in the west of the country.
Hurricane Matthew struck Haiti’s south coast. About 175,000 people were made homeless. Around 2.1 million people (20% of Haiti’s population) were affected by the hurricane.
Long-term impacts
Long-term impacts included the redevelopment of the area, clean-up and restoration, and the provision of clean water, sanitation, and housing.
Action Aid and World Nation helped provide clean water, sanitation and shelter.
For those affected by Hurricane Matthew, especially those who lost friends or relatives, the psychological hurt of losing loved ones became a long-term burden.
Questions
Outline the short-term impacts of the 2015 Nepal earthquake.
Briefly explain the long-term problems caused by the eruption of the Soufriere Hills volcano.
Compare the impacts of Hurricane Matthew on Haiti and the USA
Earthquakes present a hazard to many people and need to be managed carefully:
Preparation
There are many ways to prepare for an earthquake including warning and evacuation, building design, remote sensing, and geographic information systems (GIS).
GIS:
- Computer systems that allow different types of geographic data to be linked to a location and displayed in an easily understandable form.
The main ways of dealing with earthquakes include:
Better forecasting and warning.
Building design
Building location
Emergency procedures
There are a number of ways of predicting and monitoring earthquakes. These include:
Measurement of small-scale ground surface changes
Ground tilt
Changes in rock stress
Clusters of small earthquakes
Changes in radon gas concentration
Unusual animal behaviour, especially toads
Buildings can be designed to cope with the shockwaves that occur in an earthquake.
Examples:
Single-storey buildings are more suited than multi-story buildings as the potential for swaying is reduced.
Some tall buildings may be built with a ‘soft-storey’ at the bottom, such as a carpark on raised pillars.
This may collapse in an earthquake, so that the upper floors sink down onto it, so this cushions the impact.
Building reinforcement strategies include building on foundations built deep into the underlying bedrock, and the use of steel frames that can withstand shaking.
Land use planning is another way of reducing earthquake risk. Densely populated areas and important services such as hospitals and fire services should not be built close to known fault lines.
Remote sensing such as RapidEye and GeoEye satellite data may be used to monitor changes in ground movement. GIS systems may provide data on land use and infrastructure and highlight areas of particular vulnerability.
Questions
Outline how remote sensing can help predict earthquakes
Explain what is meant by ‘land use planning’ in relation to earthquakes
Identify ways of predicting and monitoring earthquakes
A hazard response curve shows the different stages in response to a natural hazard over time.
For example: Following the Haitian earthquake, the Red Cross estimated 3 million people need emergency aid. Seven days after the earthquake, the United Nations had delivered food to only 200,000 people. Assistance in the form of doctors, trained sniffer dogs, tents, blankets, and food was pledged from over countries. Financial assistance also poured in. The World Bank led with a $100 million commitment. However, most of this aid arrived too late for the thousands who were trapped in rubble or waiting for treatment for their injuries.
In contrast, following the 2011 Christchurch (New Zealand) earthquake, in which 185 people died, a full emergency management programme was placed within two hours. Rescue efforts continued for over a week, then shifted to recovery mode.
Questions
Describe the main short-term responses and relief following a large-scale earthquake
Suggest why the short-term responses and relief were more successful in New Zealand than in Haiti
Compare rehabilitation with reconstruction
Long term planning
Risk is the probability of a hazard event causing harmful consequences (losses in terms of death, injuries, damage to property, the economy, and the environment).
Most of the risk comes from people living in unsafe housing in areas with known fault lines. Earthquakes can also occur in areas where no fault line was known to exist.
Earthquakes killed about 1.5 million people in the twentieth century and the number of people at risk appears to be rising. More than a third of the World’s largest and fastest-growing cities are located in regions of high earthquake risk, so the problems are likely to intensify.
Hazard mapping
This shows the most likely areas that will be impacted by a natural hazard. Most earthquakes are closely linked with the distribution of fault lines, e.g., in western USA, most earthquakes occur in a linear distribution following the San Andreas fault line. However, the timing of the earthquakes is difficult to predict.
Rebuilding programmes
It is difficult to stop an earthquake from happening, so prevention normally involves minimising death, injury, damage by controlling buildings in high-risk areas, and using aseismic designs.
There is a need for rebuilding programmes, this varies with the scale of the impacts. For example, following the Christchurch earthquakes it was debated whether the whole city would be removed and rebuilt elsewhere. This was never done, and the cost would have been far too expensive, even for a relatively rich country.
Rebuilding in poor countries depends largely on the individuals themselves. Following the Haiti (2010) and Nepal (2015) earthquakes, large-scale rebuilding was needed, but the governments were too poor to undertake such measures. Many households are still living in temporary accommodation years after the events.
One option that has been used is to strengthen existing buildings (retrofitting) to make them safer in an earthquake. Engineers have created a number of ‘safe houses’ designs which withstand shaking better than some traditional designs. Safe houses can be built cheaply using straw, adobe, and old tyres, and by applying a few general principles, e.g., small windows create fewer weak spots in walls. Compressed bales of straw can be sandwiched between layers of plaster to provide some protection from earthquakes.
Exam-style Questions
- Describe the variations in earthquakes risk in Western USA
- Explain how small windows in a house help in an earthquake
- Explain how bales of straw can help protect buildings in an earthquake.
- Identify the correct order for the four terms via a Hazard response curve
- pre-disaster, rehabilitation, relief, reconstruction
- relief, pre-disaster, reconstruction, rehabilitation
- pre-disaster, relief, rehabilitation, reconstruction
- pre-disaster, relief, reconstruction, rehabilitation
- The risk of the population living in which type of area is most risky following a natural hazard?
- A rural area
- An area of low-density buildings
- A slum
- A HIC
- A primary hazard associated with earthquakes is:
- Gas leaks and fires
- Tsunamis
- Ground shaking
- Landslides and rockslides
- Describe a GIS.
- Examine the relationship between natural hazard magnitude and frequency.
- Explain why some people live in hazardous environments
- Define the term ‘vulnerability’
- Describe the main characteristics of the hazard response curve
- Examine the causes of hazards associated with earthquakes
Notes for Coastal Environment
Coastal Landforms:
Processes that occur in coastal zones:
- Wave Action from constructive and destructive waves
- Wind Action
- Mass movements (sliding and stumping) and weathering (mechanical, chemical, and biological).
Destructive Waves:
- Erosional Waves
- Short Wavelength, high height
- High frequency (10-12 per minute)
- Backwash greater than Swash
Constructive Waves:
- Depositional waves
- Long Wavelength, low height
- Low frequency (6-8 per minute)
- Swash greater than backwash
Erosional Processes:
- Hydraulic action
The force of air and water when the waves break - Abrasion
The wearing away of cliffs by the load carried by the sea - Attrition
The wearing away of the load carried by the sea. - Solution
The removal of chemical Ions, especially Calcium, which causes rocks to dissolve.
Processes of transportation:
- Traction
Larger particles are dragged along the seafloor. - Saltation
Smaller particles are bounced along the seafloor. - Suspension
Very fine materials are held up in suspension. - Solution
Dissolved sediments, e.g., calcium, may be carried in solution.
Deposition:
- A decrease in wave energy or velocity.
- A large supply of material.
- An irregular, indented coastline, e.g., river mouths.
Wave refraction and longshore drift:
- Wave refraction
- Waves approach an irregular coastline or at an oblique angle.
- Refraction reduces wave velocity and causes wave fronts to break parallel to the shore.
- Wave refraction concentrates energy in the flanks of headlands and disperses energy in bays.
- However, wave refraction is rarely complete.
- Longshore drift
When wave refraction isn’t completed, longshore drift or littoral drift occurs. The swash and backwash occur.
Swash:
- Movement up the beach Backwash:
- Movement down the beach.
Questions
- Outline the processes of weathering and mass movements that occur in coastal environments.
- Distinguish between swash and backwash
- Contrast constructive and destructive waves
Influences on coastal environments:
- Geology (rock type)
- Hard rocks, e.g., limestone give rugged landscapes
- Soft rocks, e.g., sands and gravels produce low, flat landscapes
- Geological structure
- Concordant (or Pacific-type) coastlines occur where the geological strata lie parallel to the coastline, e.g., along the California coastlines, USA.
- Discordant (or Atlantic type) coastlines occur where the geological strata are at right angles to the shoreline, e.g., the south-west coastline of Ireland.
- Processes
Erosional landscapes e.g., the east coast of England, contain many rapidly retreating cliffs. Rapid deposition e.g., the Netherlands, contain many sand dunes and coastal flats. - Sea-level changes
- These produce advancing coasts (those growing either due to deposition and/or a relative fall in sea level).
- These produce retreating coasts (those being eroded and/or drowned by a relative rise in sea level).
- Falling sea levels produce relict cliffs and raised beaches.
- Rising sea levels are associated with fjords and rias (drowned river valleys).
- An isostatic change is a local change in the level of the land relative to the sea.
- A eustatic change is a global change in sea level.
- Human Impacts
Coastal zones are used for settlement, industry, recreation, tourism, energy developments and transports. - Vegetation / ecosystem type
Mangrove, coral, sand dune, salt marsh and rocky shore add further variety to the coastline through their impact on microclimate, weathering and their indirect impact on human activities.
Questions
- Briefly outline how rock type affects coastal landform development.
- Outline how sea level changes lead to changes in coastal landforms.
- Briefly explain how vegetation may influence coastal environments.
Features of deposition:
Headlands and Bays:
A headland is a piece of highland (promontory) with steep cliffs projecting into the sea. The harder rocks form headlands that protrude.
A bay is a wide, gently curving indentation of the sea into land.
Bays may be eroded in beds of weaker rock; the weaker rock is eroded to form bays.
Cave -> Arch -> Stack -> Stump:
- Cave
- (Sea cave) an underground tunnel or chamber with an entrance from the sea.
- On a headland, erosion (due to wave refraction concentrated on the headland), will exploit any weakness, creating a cave.
- Arch
- A natural opening through a rock caused by marine erosion.
- Once the cave has been enlarged and eroded further back into the headland, both caves from each side will meet each other, forming an arch.
- Stack
- A steep pillar of rock rising from the sea, formerly part of the land but now isolated by marine erosion.
- Due to continued erosion, weathering and mass movements enlarge the arch causing the roof of the arch to collapse, forming a high standing stack.
- Stump
- An eroded stack now just appears above sea level.
- Formed by further erosion of a stack.
Wave-cut platform:
- A wave cut platform is a gently sloping area that extends from the base of a cliff, they are formed by marine erosion although weathering may also help from the platform.
- Erosion occurs between HWM and LWM.
- The cliff is eroded backwards to create an indent (notch).
- As erosion continues the notch retreats further into the cliff, and the overhang becomes larger.
Features of deposition
Deposition occurs with constructive waves, a good supply of material and a sheltered location.
Beaches
An accumulation of sand / shingle that may occur in sheltered areas or in exposed areas where there is a plentiful supply sediment.
Sediment can be carried by constructive waves and longshore drift.
Spit
A ridge of sand or shingle that is connected to the mainland at one end but the other end is in the ocean.
Spits often become curved as waves undergo refraction.
Tombolo
- A ridge of sand or shingle that connects an island to the mainland.
Bar
- An accumulation of sand or shingle that extends across a bay between two headlands (a bay bar) or deposited in water offshore parallel to the coast (offshore bar).
Prevailing wind
- The direction of the most frequent wind in the area.
Questions
- In your own words, describe how a wave-cut platform may be formed
- Describe how a stack is formed
- Outline the main characteristics of spits
Distinctive ecosystems develop along particular areas of coastlines:
Coastal Ecosystems:
Coral Reefs
- A reef composed of limestone due to the accumulation of coral. When coral die, they leave behind a hard skeleton of calcium carbonate which appears as rock.
- Sea surface temperatures of 17-33*C for growth.
- Salinity levels of 30-38 parts per thousand.
- Clear water for sunlight to reach coral reefs.
- Have a rich biodiversity.
- About 25% of the world’s sea fish breed, grow, spawn and evade predators in coral reefs.
Mangroves
- Salt-tolerant forests that grow in tidal estuaries and muddy coastlines of tropical areas.
- They require an SST (Sea Surface Temperature) of over 24*C in the warmest months.
- Annual rainfall of over 1250mm.
Home to a large biodiversity.
Sand dunes
Mounds of sand, formed by deposition of prevailing wind, usually situated along the beach.
Common in storm wave environments.
Favoured in areas of prevailing onshore wind.
Favoured in areas of a large supply of sand.
Favoured in areas of a large tidal range.
Saline, windy, and dry conditions.
Vegetation tends to be salt tolerant, plants that are adapted to salty conditions (halophytic) and drought-resistant, plants that are adapted to dry conditions (xerophytic) grasses.
Salt marshes
- Very productive and fertile ecosystems, in which vegetation grows on mud.
Salt marshes are found in sheltered locations, e.g., behind a spit and/or in tidal river estuaries.
High oxygen content.
High nutrient and light availability.
Salt marsh vegetation is halophytic (adapted to salty conditions)
Has deep roots to anchor the plant in the mud.
Has the ability to extract nitrogen directly from the air.
Formation (Salt Marsh):
A thin layer of mud forms over sand which is covered at each tide, the only plants are algae growing on the mud.
More mud deposited and the first plants appeared. The plants trap more mud and silt. The marsh is covered at each high tide and channels are cut as the water recedes.
Further plants appear high up the marsh. This accelerates mud accretion. Channels deepen as the marsh surface rises.
More plants move into the higher zones and the mud deepens. High tides still flood the marsh, but low tides are confined to the creeks, which are further eroded as the water runs off.
The marsh is now growing slowly, and the mud is very deep. Further plants colonise the higher zones. Erosion undercuts the creek banks and some collapse leaving bare salt pans above the collapse. The marsh is covered with vegetation (apart from creeks and pans), and only the highest tides fully cover it with water.
Questions
Compare and contrast the distribution of coral reefs with that of mangroves.
Contrast the conditions needed for the formation of salt marshes with those needed for the development of sand dune ecosystems.
Suggest possible reasons why there are no coral reefs off the west coast of South America.
Abiotic and biotic characteristics of a named coastal ecosystem
All ecosystems include biotic (living) and abiotic (non-living) components
Biotic:
- Living elements in an ecosystem.
Abiotic:
- Non-living elements in an ecosystem.
As sand dunes move further away from the sea, there are many changes in their biotic and abiotic components.
Not all sand dune ecosystems show the same changes shown in the diagram above. It depends in part, on the climate, geology, width of dunes, human activity, salinity, and pH of the area.
Zone 1:
- Pioneers
Zone 2:
- Shrubs and/or dune health
Zone 3:
- Thicket – dwarf trees and scrubs in areas of high rainfall
Zone 4:
- Woodland
Questions
- Describe how abiotic factors characteristics change with distance from the shoreline.
- State how biotic characteristics change with distance from the shoreline.
- Suggest how and why wind speed will vary from the seashore to the back of the dunes.
Threats to coastal ecosystems
Coral reefs
- Human impact
- Quarrying (extracting stones or other useful materials)
- Dredging (Scooping out mud, weeds and rubbish to clear the bed of a harbour, river or other area of water)
- Removal for souvenirs
- Development’ in general.
- Destructive fishing practices (using explosives).
- Fishing
Overfishing may reduce the number of grazing fish that keep coral clear of algae. - Pollution
Run-off from fertilisers or sewage can be particularly damaging as coral reefs are adapted to low nutrient levels. - Climate Change
Oceanic warming causes the coral to expel the microscopic algae (zooxanthellae) that produce the food that coral needs, leading to coral bleaching. - pH
Ocean acidification is caused by the increase of CO2 in seawater, causing the water to become more acidic. This has a negative effect on any shell-forming organism, as well as on coral reefs.
Mangroves
- Human impacts
- Hotels
- Deforestation
- Charcoal
- Wood
- Browsing by grazers (Allowing herbivores to feed off vegetation)
- Human trampling
- Souvenir collection
- Overfishing
- Waste from nearby areas + Human activities
- Pollution – Oil spills
- Changes to local landscapes
e.g., Coastal jetties – a long, narrow structure that protects a coastline from the currents and tides - Malaria control
Mangroves are a potential breeding ground for the mosquitoes. - Power plants (located along coastlines)
May raise the temperature of seawater and cause damage to ecosystems
Questions
- Briefly explain the impacts of global climate change on coral reefs.
- Suggest why mangroves are vulnerable to human activities.
- Suggest why coral reefs attract many tourists.
Sand dunes
- Human impact
- Disruption of sediment flow
- Construction of groynes.
Grazing
- Introduction of exotic species
Sand mining
- For cement and concrete (better than desert sand as it binds together better).
Vegetation trampled
- Four-wheel drive vehicles
- Sport-activities
- Car-parking
- Leads to compact soil
- Therefore, less oxygen
- Vegetation is reduced
Salt marshes
- Human impact
- Development
- Noise pollution
- Light pollution
- Affects light pollution
- Affects Reproductive success
Eutrophication
- Pollution of water due to high levels of nitrates (in fertilisers) and/or phosphates (in detergents).
- Releasing heavy metals
- Damages food chains
- Pesticides and insecticides
- Salt marshes may store pollutants and toxins for a long time.
Roads
Divided salt marshes into two sections.
Invasive species
Only occur in places where tidal flooding has been eliminated.
Salt marshes have been drained to control mosquitoes.
- Leads to a decline in biodiversity.
Questions
- Suggest why demand for sand mining is increasing.
- Outline the impacts of coastal activities on salt marshes.
- Outline reasons for the conservation of sand dunes and/or salt marshes.
So why are coral reefs, sand dunes, mangroves, and salt marshes so valuable?
Coral reefs:
- Rich biodiversity
About 25% of the world’s sea fish breed, grow, spawn, and evade predators in coral reefs. So, it is useful for fishing. - Protecting coastline
Protects the coastline from being eroded by forming barriers to protect the shoreline from waves, storms, and floods.
Mangroves:
- Water
Mangroves protect water quality by removing nutrients and pollutants from stormwater runoff before they reach seagrass habitats and coral reefs. - High biodiversity
Provide nursery habitats for many commercial fish and shellfish, therefore contributing to the local abundance of seafood.
Protect species of a $7.6billion seafood industry, which employs 100,000 + people in Florida. - Protecting coastline
Mangroves act as shock absorbers, they reduce high tides and waves and help prevent soil erosion.
Salt marshes:
- Rare biodiversity
Contains rare and valuable plants that have the ability to extract nitrogen directly from the air. - Protecting coastline
They help protect coastlines from storms, storm surges and erosion by creating a buffer between dry land and the sea. It also builds up the height of the coast by trapping slit during floods and adding new soil to their decaying vegetation.
Sand dunes:
- High biodiversity
Sand dunes are crucial for providing important ecological habitats.
Protecting coastline
They absorb the impact of storm surge and high waves, preventing and delaying floods and damage to structures.Protecting biodiversity
By building up higher and higher, large dunes can shelter the inland habitats from the wind.
Conflicts between different users
There are many different uses for coastal areas, and this can lead to conflict of many groups:
An example of successful management of conflicting land uses is the Soufriere Marine management Area in St Lucia. This uses a system of land-use zoning to allow different activities to occur in designated areas:
Questions
- Suggest a potential problem if ‘Conservation’ was a category in the table above.
- Identify the varied users (stakeholders) in the Soufriere Marine Management Area (stakeholders: any users of a coastal zone with particular interest, e.g., residents, tourists, fishermen.)
- Explain how fishing and aquaculture can lead to problems in coastal areas.
Causes of coastal flooding:
Storm surges, tsunamis, increasingly global climate change.
Storm surge
- Rapid rise in sea level caused by high wind speeds.
Tsunamis
Large sea waves caused by submarine earthquakes.
Tsunamis that occur close to the coastline have greater impact than those generated further out at sea.
Climate change
- This is leading to increasing frequency and magnitude of coastal flooding due to increased atmospheric energy.
Prediction
Coastal flood forecasts are concerned with high magnitude waves, high tides and storm surges occurring separately or together.
Most storms are tracked by satellites, especially by high-income countries (HICs), and predictions are made about their likely path. It is difficult to give much notice about tsunamis given their speed although there is a Pacific Tsunami Warning System.
With improved forecasting, many communities are able to take evasive action ahead of coastal flooding. Early warning systems in Bangladesh monitor tropical storms and monsoon rains and provide regular updates on the paths of storms and their likely impacts.
Building design
Preventing coastal erosion and flooding is the main aim. Two main approaches have been used:
Elevate buildings, so that flood water may pass under the building.
Flood-proof buildings through raised foundations, reinforced barriers, dry floodproofing (sealing a property so that floodwaters cannot enter), and wet flood proofing (allowing partial flooding of buildings)
Questions
- Suggest why it is difficult to warn against tsunamis.
- Explain how coastal buildings may be made ‘flood proof.
- Identify the main causes of coastal flooding
Coastal management strategies
Shoreline management plans
A shoreline management plant (SMP) is an attempt to protect some areas of coastline without leading to problems elsewhere. The coast is divided into sediment cells, i.e., natural units, and for each cell, governments can decide how best to manage the coast. Some areas may be allowed to be eroded and others may be given protection.
Integrated coastal zone management
Integrated coastal zone management (ICZM) is an attempt to manage all aspects of a coastal system, e.g., marine areas, land, people, and economic activities. It tries to balance protecting the coastline with its use by people and the economy. ICZM considers the interdependence of marine and terrestrial systems, stakeholders, and different scales, e.g., local and national importance.
Hard engineering
Attempts to manage coastal areas by altering natural processes through the use of man-made structures.
Soft engineering
Attempts to manage coastal erosion / flooding by working with nature, e.g., afforestation.
Questions
- Distinguish between hard and soft engineering.
- Distinguish between integrated coastal zone management and shoreline management plans.
- Briefly explain cliff drainage and revetments.
Overall questions
Define Mechanical / Physical weathering
Define Biotic and Abiotic factor
Give one feature of a coral reef
Give one factor that controls the distribution of coral reefs
Outline two marine processes
Outline one way industry can threaten coral reefs
How can coastal management strategies reduce coastal flooding?
Exam-style questions
Identify two types of mass movement that are important in coastal areas (1 mark)
Distinguish between isostatic and eustatic changes in sea level (2 marks)
Describe the distribution of coral reefs as shown in this image (2 marks)
- Describe how vegetation varies across a sand dune ecosystem (4 marks)
- Explain how spits are formed (4 marks)
- Explain the advantages and disadvantages of land-use zoning as a form of coastal management (4 marks)
- Outline the advantages and disadvantages of hard engineering methods of coastal management (8 marks)
Notes for Fragile Environments and Climate Change
Fragile environments are under threat from desertification, deforestation and global climate change.
Distribution and characteristics of fragile environments:
A fragile Environment :
- Vulnerable to change
- May find it difficult to recover from natural or human-induced changes
- Includes arid, semi-arid environments, rainforests and cold environments
Some ecosystems can cope with wide variations in climatic conditions and human pressures while others are much more sensitive to change
Natural events may cause changes such as :
- Volcanic eruptions
- Tsunamis
- Tropical cyclones
- Extreme weather
Increasingly, anthropogenic events (human-induced events) are increasing the pressure on natural ecosystems such as :
- Deforestation
- Intensive agriculture
- Urbanisations
Deforestation is the removal of forest cover – it can be complete or partial.
Here are the many types of fragile environments :
- Semi-arid environment near Uluru, Australia
- Submerged rainforest, Batang Ai, Malaysia
- Melting snow / ice caps
Questions
Define the term ‘fragile environment’.
Suggest reasons why the environment in the pictures above may be considered fragile.
State two natural threats and two human threats to fragile environments.
Desertification:
Desertification is the spread of desert-like conditions into areas that were previously green, these areas are becoming :
Biologically less productive than they once were
Can no longer support as many people at the same standard of living
There are many interrelated causes of desertification, this includes :
Drought
Population pressure
Fuel supply (deforestation for fuelwood)
Overgrazing
Migration
Up to two billion people – over one third of the world’s population, are at risk of its effects.
Here are the causes of desertification:
Sedentarisation : Making nomadic farmers remain in one area and not move around.
Deforestation:
Since agriculture started, almost one-third of the world’s forests have been cut down. This is to:
Make way for farming
Timber
Settlement
Transport developments
Mining
Other forests are flooded to make way for hydroelectric schemes. Some of the forests have been destroyed due to acid rain, especially in areas consisting of tropical rainforests.
Questions
Define the term ‘desertification’.
Outline the potential causes of desertification.
Describe the global variations in the extent of deforestation.
Natural climate change and the enhanced greenhouse effect:
Natural climate change
There are many reasons for long-term changes in the Earth’s climate (and they all pre-date the present global climate change). This includes:
- Tectonic plate movement
- Mountain building
- Volcanic activity
- Solar output
- Atmospheric dust
- Changes in the Earth’s position relative to the Sun
Global Climate Change:
- Recent changes in global temperatures
- Due to human activities
- Also known as global warming/ climate crisis/ enhanced greenhouse effect
The Milankovitch cycles show that the amount of solar energy reaching the Earth varies with :
- Changes in the Earth’s orbit (its ‘tilt’ and ‘wobble’) and direction of rotation
- The Earth’s orbit varies over a timescale of about 100,000 years
- When it is further from the sun, it receives less energy.
- In addition, when the tilt is greater, seasons are longer
- The ‘wobble’ determines which hemisphere is facing the Sun – northern or southern
Milankovitch cycles are variations in the amount of solar radiation received by the Earth due to variations in the Earth’s orbit, its tilt and its wobble.
Other natural causes include volcanic eruptions.
Those more likely to cause changes to climate are large eruptions, especially in tropical areas. For example, the eruption of Mt Pinatubo in the Philippines in 1991 led to a drop in the mean global temperature of 0.3*C. Even by 2005, the drop in global temperatures due to Mt Pinatubo was 0.1*C. Sunspot activity (solar flaring) occurs on an 11 and 22 year cycle. Atmospheric dust is also believed to block or reflect incoming solar energy, thereby leading to lower temperatures on Earth.
Human causes of climate change:
The greenhouse effect is the process in which certain greenhouse gases allow short-wave radiation to pass through the atmosphere, however, trap a portion of the outgoing long-wave radiation, hence raising temperatures.
Types of greenhouse gases :
- The most common is water vapour
- This accounts for about 50% of the natural greenhouse effect
Gases which account for human causes of climate change are :
- Carbon dioxide (CO2)
- Methane (CH4)
- Chlorofluorocarbons (CFCs)
The enhanced greenhouse effect:
Atmospheric levels of CO2 have risen from around 315 parts per million (ppm) in 1950. Now, they have increased to over 420 ppm (2020). They are predicted to rise to 600 ppm by 2050
The rise is due to human activities such as :
Burning fossil fuels (coal, oil, natural gas)
Land-use changing such as deforestation
Questions
Outline the impact of Mt Pinatubo’s eruption between 1991 and 2005.
Briefly explain the greenhouse effect.
Describe the trend in global average temperature change
The impacts of desertification:
Every year, up to 12 million hectares of land, 20 million tonnes of grain and 20 million tonnes of cereal are lost to desertification every year. Soil exhaustion decreases world food production
The impacts of deforestation:
Biodiversity :
The variety of living organisms in an environment
This includes habitat diversity, species diversity and population (genetic) diversity
Pastoralism is a farming system based on the rearing of animals.
Fuelwood is the use of trees and other vegetation as a source of fuel.
Questions
Describe the impact of deforestation on soil.
Identify the impacts of deforestation on the water cycle.
Briefly explain why deforestation may lead to increased risk of drought and fire.
Impact of climate change on fragile environments and people:
Rising sea levels:
Oceans are warming due to the ‘steric effect’. As the expansion of seawater gets warmer, the sea levels are rising.Therefore, ice on land is melting. Even if there was no ice melting, the oceans would increase in size as warmer water expand
Tens of millions of people are at risk from rising sea levels because:
Many low-lying islands and many of the world’s megacities are less than 10m above sea level.
Coastal flooding is also a major risk
Food production in coastal areas is likely to be affected by saltwater intrusion
Climate change is likely to lead to an increase in hazards. Increased atmospheric energy will lead to an increase in tropical storms (hurricanes), droughts and fires.
In the Amazon rainforest, there has been an increase in drought events, such as those of 2005, 2010 and 2015. These have led, in part, to increased tree mortality as well as the reduction of rainfall over the rainforest.
Similarly, in the Middle East and North Africa, water stress is likely to increase due to falling rainfall levels and increased demand for water.
Ecosystem changes: The effect of climate change is likely to cause :
- Latitudinal shifts relative to the Equator
- Altitudinal shifts as biomes move up-slope
- At high altitude and latitude, biomes may have nowhere to retreat and may become extinct
Ocean acidification is the decreasing of the pH of the oceans due to increasing levels of carbon dioxide absorbed by seawater.
In the world’s oceans, changes such as increased ocean temperatures and ocean acidification can lead to coral bleaching, decline in species that build their own skeletons, as well as fish species migrating pole-wards into cooler water.
Decreased employment opportunities: Climate change may lead to major job losses in different environments.
Agriculture may become less productive in areas which become drier and hotter
Tourism in many mountainous areas will decline as glaciers retreat
Fishermen may have to change the species that they catch.
Indigenous Populations are ethnic groups who are the original/earliest known inhabitants of a region, also known as ‘aboriginal’ people.
The area of tropical rainforests worldwide has halved since 1800 to 1.4 billion hectares. As a result of deforestation, up to 100,000 species may become extinct every year. Tropical forests are a vital source of material for medicines. Of the 3000 plants that may help cure cancer, 70% are found in tropical forests.
Changing settlement patterns: Settlements in low-lying areas may be abandoned or relocated Many settlements – or parts of settlements such as those along the USA’s east coast will require considerable protection from rising sea levels and coastal flooding, otherwise will have to be abandoned.
Health and well-being: A rise in temperature of 2*C could expose up to 60 million more Africans to malaria. Mosquitos would be able to breed in areas previously too cool for them.
Rising temperatures could lead to increased risk of dehydration, malnutrition and heat stress.
Agricultural crop yields, limit to cultivation and soil erosion: The decline in water resources may make it difficult for farmers to continue the type of farming they currently practise. They may have to change crop/type of farming and could be forced out of farming altogether.
A rise in temperature of 2°C could lead to 200 million people experiencing hunger. A rise in temperature of 3°C could lead to up to 500 million people experiencing hunger.
Questions
- Outline two reasons why sea levels are rising .
- State the projected range of sea levels by 2100 :
- At current level
- Due to possible ice melt from Antarctica Suggest why Kivalina settlement may have to relocate
- Suggest why the Kivalina settlement might have to relocate.
Responses to desertification, deforestation and climate change vary depending on a country’s level of development:
Desalination refers to the removal of salts from seawater to produce fresh water for human consumption and irrigation use
In many dry areas, seawater is a vital potential source of freshwater and can be used to combat desertification. Due to high energy input, the financial costs of desalinating seawater are generally still high. Alternative water sources are not always available. There are around 20,000 desalination plants operating worldwide producing almost 90 million m3 of water per day, which is used for 300 million people.
Other sources of water in dry areas include groundwater. This is fresh water stored in underground rocks (aquifers). This could be brought to the surface by using pumps. However, in dry areas groundwater is a finite, non-renewable resource.
Here are other methods to tackle desertification :
Overgrazing is the impact of too many livestock feeding on vegetation. This leads to a decline in the quality and amount of vegetation cover
Over-cultivation are the attempts to grow too many crops over a period of time, which lead to a decline in soil quality
High yielding varieties (HVVs) are genetically modified crops that produce greater yields per hectare, depending on whether the soil conditions are correct or not.
Agroforestry: combining agriculture and forestry
Questions
Explain how desalination may help in the management of desertification
Outline the advantages of using trees to combat desertification
Explain the term ‘zero tillage’
Zero tillage refers to not ploughing the soil.
Case study: Approaches to the sustainable use and management of a name rainforest : the Amazon rainforest, Brazil
The Central Amazon Conservation Complex is one of the world’s largest conservation areas, covering 53,230 km2. It protects several areas with rare, endemic and/or endangered species. It is the largest protected area in the Amazon, formed by the merging of the Jau National Park with The Anavilhanas National Park, The Amana Sustainable Development Reserve and The Mamiraua Sustainable Development Reserve.
Sustainable development is the development which improves basic living standards, however, not at the expense of future generations
Brazil’s Forest Code: A law that requires landowners in the Amazon to maintain a proportion of their land (80%) as forest. It was passed in 1965 and revised in 2012
Initiatives at a local scale: Some indigenous groups use many ways to use the rainforest sustainability
In the Yanesha Forestry Cooperative Project, farmers cut a strip of rainforest some 20-40 metres wide, farm it and then let it recover. The narrow belt allows rapid recovery and secondary forests grow back within twenty years.
Other communities enrich their soils by adding animal bones and charcoal. This increases soil fertility and allows them to farm the land more productively
Others plant fig trees on degraded land, which attract birds and bats which bring in seeds from neighbouring forests. The birds and bats deposit seeds in their droppings, helping the forest to regenerate
Questions
Identify one advantage and one disadvantage of the Central Amazon Conservation Complex.
Identify one advantage and one disadvantage of a small-scale (localised) project
State the main objective of Brazil’s forest code.
Responses to global warming and climate change
Responses to climate change can take two main forms :
Mitigation: Attempts to prevent climate change from happening
Adaptation: Measures to manage the impacts of climate change
Mitigation refers to programmes to try to prevent climate change from happening or try to reduce the scale of climate change that occurs
Adaptation refers to the measures that are taken to manage the impacts of climate change, this includes preventing coastal erosion and protecting cities against sea level rise.
Individual choices: There are many actions that individuals can do to reduce their own contribution to climate change. This includes:
Walking
Cycling (better than using a car)
Eating less meat and fewer dairy products
Switching to renewable sources of energy
The response of the United Kingdom
Adaptation: There are many ways in which UK is adapting to climate change, which include:
Improving and increasing flood defences
Improving public transport
Adding more bus and cycle lanes
Mitigation: The UK’s progress on climate change mitigation is predicted to stall in the 2020s, partly as a result of a lack of new climate policies in recent years. This is also due to failure to meet afforestation targets and a lack of progress in developing carbon capture and storage (CSS) technology
Carbon capture and storage (CSS) is the process of capturing carbon emissions and storing the carbon underground in safe rock formations
Nevertheless, the UK now burns far less coal than it used to. There is potential for more renewable energy, especially wind and solar powered energy.
UK : Climate change pledges and targets:
The response of China
China: Climate change pledges and targets:
China has responded in many ways to the threat of global climate change by reducing its consumption of coal .This is partly due to changes in China’s economy: There is more growth in the service sector, and less growth in the heavy industries (which can be energy-intensive and can also use vast amounts of cement and concrete)
In 2015, China announced its coal consumption would peak by 2020. It would not be building any new coal-fired power stations. China has also invested heavily in wind and solar energy. The Three Gorges Dam makes a significant contribution to the production of renewable energy, although the vast amount of concrete used in building the dam would have contributed to global climate change.
China is also providing incentives for buying hybrid vehicles (vehicles that can run on electricity as well as fossil fuels) and electric vehicles. China’s high-speed trains transport nearly 3 million passengers daily, thereby reducing a large number of people from using motor vehicles.
– Electric vehicles. Hence. China is enforcing stricter fuel-efficiency standards.
Adaptation: China has a very varied climate and ecosystems, which makes adaptation to climate change very complicated. Urban populations such as Shanghai are extremely vulnerable to a rise in sea levels. Water scarcity in the north has led to changes in crop productivity, increased flood risk and increasingly frequent and intensive droughts.
Questions
- Outline methods in which individuals could help contribute to reducing climate change
- Suggest how China’s energy consumption is changing
- Comment on the UK’s attempts to reduce climate change
Exam-Style Questions
- The most important greenhouse gas is: (1 mark)
- Carbon Dioxide
- Methane
- Water Vapour
- Chlorofluorocarbons
- Climate Change mitigation refers to: (1 mark)
- Measures that deal with the impacts of climate change
- Developments that improve basic living standards without harming future generations
- Attempts to prevent climate change from occurring
- Use of technological developments such as HYVs
Define the term ‘indigenous population’ (1 mark)
Suggest why an increase in 2°C could lead to increased risk of death in Africa. (2 marks)
Explain two potential impacts of rising sea levels. (4 marks)
Identify individual choices to deal with global climate change. (4 marks)
Explain why oceans are experiencing acidification. (2 marks)
To what extent is it possible to manage rainforests sustainably? (6 marks)
Examine the main measures to tackle desertification in developed and emerging/developing countries. (12 marks)
Notes for Urban Environments
Urbanisation:
The process by which an increasing percentage of a country’s population
Comes to live in towns and cities (Urban areas)
It may involve rural-urban migration, natural increase and reclassification of rural settlements as they are engulfed into an expanding city
LLEDCs : Least Less Economically Developed Countries
LEDCs : Less Economically Developed Countries
NICs : Newly Industrialised Countries
MEDCs : More Economically Developed Countries
Suburbanisation :
- Outward growth of towns and cities
- To engulf surrounding villages and rural areas
This may result from the out-migration of population :
From the inner urban areas to the suburbs
From the inward rural-urban movement
Counter-urbanisation :
- A process involving the movement of population
- Away from the inner urban areas to smaller urban areas and rural settlements such as new towns, commuter towns and villages
- On the edge or just beyond the city limits/rural-urban fringe
Questions
- Distinguish between urbanisation and counter urbanisation.
- Contrast the trends in the levels of urbanisation in the image above.
- Define the term ‘least less economically developed countries’.
Rapid urbanisation and growth of megacities
There are several reasons for rapid urbanisation in LICs and NICs. These include :
- In urban areas, the prospects of finding employment, better paid jobs and more secure jobs are creator
- This is known as an economic pull factor
- In urban areas, there are better provisions of education and health facilities
- This is known as a social pull factor
- In rural areas, there are fewer economic opportunities. Farming is low and insecure
- This is known as an economic push factor
- In rural areas, there is an increased chance of danger (subject to climate change and natural hazards)
- This is known as a physical push factor
- In rural areas, there is poor access to clean water, sanitisation, health care and education
- This is known as a social push factor
Consequently rural-urban migration may be large scale :
- Leading to rural depopulation
- The growth of population in urban areas
- The majority of those who migrate are young adults
A megacity is a city with over 10 million people. By 2018, there were 33 cities with a population over 10 million. Of these, 27 cities were in developing/emerging countries.
Megacity growth may be slowing down. Several factors may help explain this :
- In many cities in the developing world, slow economic growth (or economic decline) has attracted less investment as well as fewer people
- Lower rates of natural increase have occurred as fertility rates have come down
Questions
- Outline the reasons for the rapid growth of urbanisation
- Define the term ‘megacity’
- Identify from the table above the megacity with (a) greatest relative increase, (b) largest absolute increase and (c) population decline.
Problems associated with rapid urbanisation
For individuals and families, urban areas offer the prospects of quality of life. For some, migration to urban areas improves their standard of living. For others, migration may result in unemployment, poor quality, housing and deprivation
Rapid urbanisation is associated with 5 categories :
- Congestion
- Transport
- Employment
- Crime
- Environment
1. Congestion
- Rapid urbanisation can lead to large-scale congestion of people (and economic activity)
- For example, in Mumbai, up to 1 million people live in the Dharavi slum, an area that covers about 2 km2. Some 99% of houses do not have a private toilet. Such conditions of congestion fuel the spread of diseases such as COVID-19 in 2020
2. Transport
- Congestion is a problem due to :
- Vast numbers of cars on the road
- Poor quality / size of roads in many cities
- Urban traffic congestion varies with days of the week, time of day, weather and seasons
- Traffic is more congested on weekdays – especially during peak flow times in the morning and the evening
- Congestion may be related to festivals, large sporting events and national holidays
- Congestion may decrease in the summer as more people walk/cycle to work, and schools are closed
3. Employment
- Most migrants are drawn to large cities by the prospect of employment and better standards of living
- Many are faced with unemployment, underemployment (working only occasionally or just a few hours a day/week), low pay and lack of job security
- Many are forced to enter the informal sector: the unregulated economy, with casual jobs such as selling food on the street and domestic service
4. Crime
In many large urban areas, crime is a problem. This may be partly related to large-scale unemployment and lack of job opportunities
Often, crime is concentrated in areas of high population density.
In Kaduna, northern Nigeria, crime is highest in areas of high population density. The main criminal activity is burglary/theft.
In wealthier areas, the more common criminal activities include car theft and damage.
5. Environment
Environmental issues are widespread, major problems include waste products and waste disposal
In LICs, 25% of urban dwellers have no adequate sanitation and no means of sewage disposal
Air pollution is common in cities in rapidly industrialising countries: Delhi has some of the worst air quality in the world. As a result, this poor air has been linked to higher rates of death
Water pollution is widespread as water is used as a dumping ground for agricultural, industrial and domestic waste for untreated sewage
Water shortages have become more frequent in some cities.In Bangkok, overuse of groundwater has led to subsidence
For some people, not being connected to a water tap means that they have to buy water from sellers which is very expensive
Questions
Estimate the population density of Dharavi
Suggest why there are variations in traffic congestion
Explain why poor people may pay more for their water than rich people
Urban land use patterns
Cities face a range of social and environmental challenges resulting from rapid growth and resource demands
Urban land use refers to activities such as industry, housing and commerce, which may be found in towns and cities.
Land values :
Land values decrease with distance from the city centre
Land values increase with accessibility to good transport routes
Land use :
The main function for which an area is used for. Ex: residential, industrial or commercial purposes
Accessibility is how easy it is to get to a place
Concentric zone model:
A model based on Chicago in the 1920s
The city is growing spatially due to immigration and natural increase
The area around the CBD has the lowest status and highest density housing
Residents move outwards with increasing social class and their homes are taken by new migrants
The Central Business District (CBD)
Most of the commercial activity is found here – central area
It is the most accessible (to public transport)
Has the highest land value
Tends to have high rise buildings
Owing to the strong demand for land
Generally a shortage of space
Most residential areas are found in the suburbs :
- The suburbs refer to the outer part of an urban area
- Suburbs consist of residential housing and shops of a low order (newsagents, small supermarkets)
The rural-urban fringe: boundary of a town or city between urban and rural functions where new buildings are changing land use from rural to urban.
Industrial areas occur in several locations, such as the inner city (the area surrounding the CBD), major transport routes and in edge-of-town locations.
In many cities, the inner city is the older industrial area of the city. It may suffer from decay and neglect, leading to social problems. Inner cities are characterised by poor quality terraced housing with old manufacturing industry nearby
Questions
- Define the term – accessibility
- Suggest contrasting reasons for the location of industrial areas in cities
- Explain how and why land values vary in a city
Urban challenges – developed countries
All urban areas may face challenges, even prominent cities, such as London, UK.
- One of these is to provide food for their residents
- There are complex supply chains, which can be badly disrupted.
- London’s food sector accounts for £20 billion and about 10% of jobs in the city. There are many food banks in London. These help to feed 1.5 million people who go hungry
- There are complex supply chains, which can be badly disrupted.
Food bank : A charity providing food for those who cannot afford to buy sufficient food to meet their needs
- Most of London’s energy comes from gas, although there is a plan to produce 15% of London’s energy from renewable resources by 2030. At present, less than 1% comes from renewables
- Transport faces issues regarding congestion and sustainability
- Central London has a 20 mph speed limit.
- It also has a congestion charge to limit the number of car trips made
- However the number of car journeys is increasing, which reduces the reliability of bus journeys due to increased congestion
- London has a well-developed underground network, however some parts of it have very poor air quality
- London produces a huge amount of waste :
- Some of this is disposed in landfill sites
- Some is burnt to generate electricity
- Some is recycled
- On average, most households produce around 1000 kg of waste yearly
Landfill: Dumping of waste materials in the ground
- London has a concentrated resource consumption due to its size and wealth
- Its ecological footprint is 6.6 global hectares (gha) per person, compared with world
average of 2.8 gha - The UK’s overall figure is 6.3 gha
- Its ecological footprint is 6.6 global hectares (gha) per person, compared with world
Ecological footprint: A measurement of the amount of land needed to provide a population with the resources it consumes such as water, food and energy. It is measured in global hectares (gha)
London is a multicultural city, however, based on 2011 census data, segregation is evident. There is a higher concentration of white British towards the edge of the city. In contrast, some minority ethnic groups are concentrated nearer the centre, this involves Bangladeshis (in the east end) and Indians and Pakistanis (in the west, east and some parts of the south).
Multicultural: An area with many different races and socioeconomic groups.
Segregation: Keeping apart people of different racial backgrounds
Questions
Suggest why air quality in London varies spatially and temporally
Define the term ‘ecological footprint’
Suggest why London has a high ecological footprint
London has a high ecological footprint per person because it has a wealthy population and so their consumption of energy, water, transport, material and food is likely to be much higher than that of people who are less well off.
The total number of slum dwellers in the world stood at 980 million people in 2015, which represents about 32% of the world’s urban population. 78.2% of the urban population is in LICs.
Mumbai experiences many of the problems resulting from rapid city growth, poverty, unemployment, underemployment, limited access to health care, limited access to education, poor sanitation and poor access to electricity.
This hence results in :
Most of the residents living in slums/squatter settlements – these have limited security of tenure
Dharavi, the main slum in South Mumbai consists of an area of 2km2, home for up to 1 million people
Due to its close proximity to Mumbai’s financial and commercial district, there is a greater pressure to clear parts of Dharavi. This is to allow for modern developments
Squatter settlement: An illegal settlement where homes have been built by the residents
Positive and negative impacts of living in a slum:
| Positive aspects | Negative aspects |
| They are points of assimilation for immigrants. | Security of tenure is often lacking |
| Informal entrepreneurs can work here and have clients extending to the rest of the city. | Basic services are absent, especially water and sanitation |
| Informal employment, based at home, avoids commuting. | Overcrowding is common |
| There is a strong sense of kinship and family support. | Sites are often hazardous |
| Crime rates are relatively low | Levels of hygiene and sanitation are poor, so disease is common |
There are 4 aspects to take into account for Dharavi, this is :
Informal economy
Water and sanitisation
Air Quality
Quality of life
Informal economy (Dharavi)
The unregulated and untaxed economy, sometimes called the black market
The formal economy refers to the regulated economy, for example, offices factories and services such as health care, education and government
Much of the formal economy produces goods and services for wealthy people
By contrast, the informal economy is small scale, locally owned and labour intensive
Dharavi has many informal activities that provide a livelihood for many of its residents
Up to 85% of Dharavi adults work locally; there are major recycling industries as well as pottery industries
Working conditions for recycling industry can be very dangerous
Water and sanitisation (Dharavi)
The Dharavi slum has a poor sewage system and poor drainage system
The area is subject to floods usually in the wet season
There are up to 4000 cases per day of diphtheria and typhoid – partly the result of a lack of a proper sewage system
Water access is from standpipes, so access to water is limited. Many pumps are only available for two hours per day
Many people used the Mahim creek for washing, however, it is also used for urination as well as defecation
Open sewers drain into the creek, which brings a range of pollutants. Dharavi has a very limited number of toilets (one for every 500 people)
Air quality (Dharavi)
Air quality in Dharavi (Mumbai in general) is poor, this is due to industrial and vehicle emissions
Air quality in general is worse in winter (November to February), this is due to less rainfall to clear the air
Quality of life (Dharavi)
- Many aspects of Dharavi lead to a low quality of life, this includes lack of security of housing (up to 90% may be illegal) and low life expectancy (about 50 years)
- There are many jobs available: Dharavi’s informal economy is worth between US $500 million and $1 billion a year (£250 million – £500 million)
Questions
- Outline one advantage and disadvantage about Dharavi’s location.
- Define the term ‘informal economy’.
- Explain why water pollution is a problem in Dharavi
Different strategies can be used to manage social, economic and environmental challenges in a sustainable manner
Development of the rural-urban fringe
The rural urban fringe is the edge of a city where it meets the countryside
There are many pressures on the rural-urban fringe, which include :
- More housing: e.g. Blackbird Leys, Oxford
- Industrial growth: e.g. Oxford Science Park
- Transport Infrastructure: e.g. M25, London
- Recreational pressures for golf courses and sports stadiums: e.g. Kassam Stadium, Oxford
The advantages and disadvantages of out-of-town (rural-urban fringe) shopping centre:
| Advantages | Disadvantages |
| Plenty of free parking | They destroy large amounts of undeveloped, valuable habitats |
| Lots of space so shops are not cramped | They lead to pollution and environmental problems at the edge of town |
| Easily accessible by car | They only help those with cars |
| Developments on the edge of town reduce the environmental pressures and problems in the city centres | Successful out-of-town developments may take trade away from city centres and lead to a decline in sales in the CBD |
Greenfield and brownfield sites
A greenfield site is a site that has not been previously developed on. Most greenfield sites are on the edge of town, not necessarily so.
A brownfield site is a site that was once developed, but is now derelict/abandoned
The advantages and disadvantages of greenfield and brownfield sites:
| Advantages of greenfield sites | Disadvantages of greenfield sites |
|
|
| Advantages of brownfield sites | Disadvantages of brownfield sites |
|
|
Questions
Identify the part of the city most likely to have a greenfield site.
State the advantages of developing brownfield sites.
Describe the disadvantages of developing greenfield sites.
Sustainable urban systems
Large cities are often considered unsustainable because they consume huge amounts of resources and produce vast amounts of waste.
Sustainable urban development meets the needs of the present generation without compromising the needs of future generations.
The Rogers’ model (cities for a small planet) compares a sustainable city with that of an unsustainable one. In the sustainable city, inputs are smaller and there is more recycling.
Linear city: A city with large inputs of resources and large amounts of waste
Circular city: A city with a high proportion of renewable resources and a high proportion of recycling.
To achieve sustainability, a number of options are available :
Reduce the use of fossil fuels (can be done by promoting public transport)
Keep waste production to within levels that can be treated locally
Provide sufficient green spaces
Reuse and reclaim land, e.g. brownfield sites
Encourage active involvement of the local community
Conserve non-renewable resources
Use renewable resources
Compact cities minimise the amount of distance travelled, use less space and require less infrastructure (pipes, cables, roads etc); they are easier to provide a public transport network for, and reduce urban sprawl
If a compact city covers too large an area, it becomes congested, overcrowded, over-priced, polluted and therefore making it unsustainable.
A sustainable future requires:
- Use of appropriate technology, materials and design
- Acceptable minimum standards of living
- Social acceptance of projects
- Widespread public participation
The main dimensions of sustainable development are :
- Provision of adequate shelter for all
- Improvement of human settlement and management
- Sustainable land use planning and management
- Integrated provision of environmental structure (water, sanitation, drainage and solid waste management)
- Sustainable energy and transport systems
- Settlement planning in disaster-prone areas
- Sustainable construction industry activities
- Meet the urban health challenge
Questions
- Describe the main characteristics of a linear city.
- Outline how a circular city is sustainable.
- Outline two social demands in the sustainable city.
Stakeholders in managing urban areas
A stakeholder refers to any group or individual who is affected by, can affect or has an interest in development (ex: new housing or a new out-of-town development).
Some stakeholders may be supportive of the development, while other stakeholders may be against it. Other stakeholders may see both advantages and disadvantages of the development
Stakeholders include individuals involved in a scheme, national and local governments, charities, local churches, local planners, building companies, property owners, retailers, developers and estate agents.
For example, the Houldsworth Village Partnership in Manchester involves at least 60 different stakeholder groups, including the Stockport Metropolitan Council, the Guinness Northern Counties Housing Trust, the University of Manchester, St Elisabeth’s School, existing residents and traders, the Stockport Sports trust and the Reddish Crime Panel
Some stakeholders may have conflicting interests, for example :
- Established residents in areas desiring no new developments
- Compared with younger people desiring new, affordable housing developments
Corporate objectives may differ from individual ones
The impact of a new development may have negative impacts on others, for example, an out-of-town development may create jobs locally, however, this also leads to increase in congestion, increase in air pollution and a decline in habitat.
Stakeholders may have to compromise their individual beliefs and values for the greater good
However, it is possible for stakeholders with an interest in the success of a partnership/development to attempt to minimise the impact on stakeholders with negative views. For example : A new housing development retaining open space and vegetation rather than having high density housing only.
Questions
- Explain the likely view of two contrasting stakeholders (e.g. existing residents and first-time buyers) about a new local housing development.
- Identify one private and one public stakeholder in the Houldsworth Village Partnership.
- State one reason why it may be difficult to reach agreement on how best to develop urban areas sustainably.
Exam-Style Questions
- Urbanisation is defined as: (1 mark)
- The growth of urban areas
- An increase in the proportion of people living in urban areas
- An increase in the population living in urban areas
- All of the above
- A greenfield site is: (1 mark)
- An area of land that has never been developed
- An area of conservation
- An increase in the population living in urban areas
- All of the above
- The proportion of people who live in slums around the world is approximately: (1 mark)
- 10%
- 30%
- 50%
- 70%
- Compare push and pull factors in relation to urbanisation. (2 marks)
- Outline the advantages of compact cities (3 marks)
- Describe the main locations in which industry is located in an urban area. (4 marks)
- Define the term ‘Squatter settlement’ (1 mark)
- Suggest reasons for the growth of counter-urbanisation in developed countries (4 marks)
- Analyse how urban areas may be made more sustainable (8 marks)
Answers to Questions
Page 7
The region with the greatest number of tropical cyclones per year is the Western Pacific Ocean, with an average of 26.
Most volcanoes occur at plate boundaries. They occur at constructive plate boundaries where new magma reaches the Earth’s surface due to convection currents. They also occur at subduction zones where oceanic crust plunges under continental crust or other oceanic crust and is melted. Volcanoes may also occur at hotspots – these are areas where an isolated plume of magma burns through oceanic or continental crust and creates volcanic eruptions.
An earthquake of magnitude 7.0 is one thousand times more powerful than one of magnitude 4.0.
Page 8
The main conditions needed for the formation of tropical cyclones include oceans that have sea surface temperatures of over 27 ̊C, for enough evaporation to occur. They develop away from the Equator as there is insufficient rotation (Coriolis Force) there. They also develop in low pressure systems where the vertical wind shear is limited.
A category 3 tropical cyclone has winds of 178–209 km/h and a storm surge generally 2.7–3.6m above normal.
A category 5 tropical cyclone is likely to cause complete roof failure on many residences and industrial buildings. Some small buildings will be blown over or blown away.
Page 10
- A lahar is a type of mudflow in which volcanic ash mixes with water. It is a secondary hazard. In contrast, a pyroclastic flow is an explosive cloud of superhot material ejected by the volcano in a violent eruption. It is a primary hazard.
- Primary hazards are those that occur directly as a result of a volcanic eruption e.g., lava flows, ash fallout, gas emissions and/or pyroclastic flows. In contrast, secondary hazards are those that result from the interaction of materials ejected by the volcano with other materials. For example, when ash mixes with rain/water/snow it can produce lahars (mudflows); when emissions of sulphur mix with rain they produce acid rain and can lead to acidification. Other secondary hazards occur when emissions have an impact on other physical systems e.g., emissions of ash may form a layer in the atmosphere leading to a reduction in the amount of solar radiation reaching the Earth’s surface, causing global cooling.
- The primary hazard of an earthquake is ground shaking. This does not lead directly to many deaths but the damage that it can cause to buildings may lead to many deaths. Most people are killed by the collapse of buildings, landslides, and rockslides, or, in coastal regions, from resulting tsunamis which overwhelm people and destroy buildings.
Page 10-11
People live in hazardous areas because either they believe the advantages of living there outweigh the disadvantages or they have little choice over where they live as they are too poor to afford better.
As Mt Etna is a volcano, it is a hazard. There are several craters which have erupted in the past and could erupt/explode in the future. The restaurant/building and the number of cars suggests that this area could be a tourist attraction, and that there are many jobs available in the tourism/hospitality sector.
People live in areas that experience earthquakes because there are also employment opportunities. Many large cities experience earthquakes, e.g., Tokyo and Los Angeles. People may perceive that the risk of an earthquake affecting their own family is remote.
Haiti suffered a much greater loss of life than the USA (546 fatalities and 128 people missing compared with 47 fatalities in the USA. However, the USA experienced much greater economic loss, $10 billion, compared with $2.8 billion in Haiti.
Page 12
People who are poor, the elderly, the very young and women are more vulnerable to natural hazards for several reasons e.g., they may live in poor quality housing; they may not be very mobile (no form of transport); they could be carers for the young/old/people who are sick or have disabilities. For these reasons they may not be able to get away very easily from an impending natural hazard.
The risk of death from natural hazards increases with poverty. For example, data shows that high-income communities experienced 26% of the disasters between 1994 and 2013, but only accounted for 13% of the deaths. In contrast, low-income populations experienced just 17% of disasters but accounted for 33% of deaths. The lower middle-income population experienced a higher proportion of deaths to disasters whereas the upper middle-income experienced a higher proportion of disasters to deaths. Thus, the risk of death from disasters increases with poverty.
Some areas experience more natural hazards because they are located along fault lines, near volcanoes or are in coastal areas in the tropics (risk of tropical cyclones). Some areas are very steep while flat coastal areas may be at risk of storm surges and/or tsunamis.
Page 14
About 9000 people were killed and 20,000 injured. Overall, around 8 million people were affected; 600,000 homes were destroyed and over 250,000 homes were damaged. Water and electricity were not available in many places. Temporary shelters were provided for those made homeless. Temporary schools were made of bamboo and tarpaulin.
Long-term impacts included the establishment of an exclusion zone, the creation of the Montserrat Volcano Observatory and the development of new infrastructure and buildings in the north of the island including homes, hospitals, roads, and expansion to the island’s port. However, once these were rebuilt the island’s population fell due to a combination of few jobs, declining tourism, and rising prices.
Rehabilitation involves the provision of temporary housing and services. This is meant to be a short-term process. Reconstruction refers to the permanent rebuilding and provision of services. Both aim to improve the quality of life of those affected but one is temporary, and one is permanent.
Page 15
Remote sensing can help predict earthquakes as it can measure small-scale ground surface changes and ground tilting from a large distance.
Land-use planning refers to using different areas for different land uses. In the case of areas where there is an earthquake risk, important services such as hospitals and fire services should not be built close to known fault lines, and areas of high housing density should be placed away from steep slopes which are more vulnerable to failure in an earthquake than flatter areas.
Earthquakes can be predicted and monitored using measurements of small-scale ground surface changes, ground tilt, clusters of small earthquakes, unusual animal behaviour, changes in rock stress and changes in radon gas concentration. However, monitoring occurs once the earthquake has happened – it is difficult to predict when an earthquake will occur, and how strong it will be.
Page 15-16
The main responses following a large-scale earthquake are to rescue people who are trapped and to provide emergency relief such as food and water, medication, and shelter. This may typically last for up to a few days or weeks.
One of the main reasons why the earthquake in Christchurch was easier to manage was because fewer people were affected. Although the earthquakes were of similar magnitude, the damage was much more in Haiti due to the poor building standards. In contrast, buildings were of a higher quality in New Zealand and there was less destruction. In addition, in Haiti many of the GIS is a computer system that allows different types of geographic data to be linked to a location and displayed in an easily understandable form.
Page 16-17 (Exam-style questions)
The earthquake risk is highest in the western parts of the USA and declines eastwards.
Smaller windows mean there are fewer weak spots in a building’s structure. In an earthquake most of the built structure remains intact and can support the rest of the building. With larger windows, a greater proportion of the building is weak, and so the risk of collapse is greater.
Compressed bales of straw can be placed between layers of plaster. The straw is held together by nylon netting. The straw acts as a shock absorber and can reduce the impact of small earthquakes.
C
C
C
A GIS is a computer system that allows different types of geographic data to be linked to a location and displayed in an easily understandable form.
The relationship between magnitude and frequency is inverse, i.e., in general low magnitude events have a high frequency of occurrence, whereas high magnitude events have a low frequency. Some people choose to live in hazardous environments because of the potential jobs they create e.g., tropical coastal areas are associated with tourism and fishing; some volcanic soils are fertile and good for farming. Others may have little choice where they live and may be forced to live in relatively unsafe locations because the better sites have already been developed.
Some people choose to live in hazardous environments because of the potential jobs they create e.g., tropical coastal areas are associated with tourism and fishing; some volcanic soils are fertile and good for farming. Others may have little choice where they live and may be forced to live in relatively unsafe locations because the better sites have already been developed.
Vulnerability refers to the geographic conditions that increase the susceptibility of a community to the negative effects of a natural hazard.
Following a natural hazard, the first stage is to rescue people. People are provided with emergency aid, shelter, food, and medication. Rehabilitation involves the provision of temporary housing and services, and this may last for many weeks. Finally, there is the reconstruction programme. This can take many years depending on the funding that is available.
Earthquakes can cause primary and secondary hazards. The primary hazard associated with earthquakes is ground shaking. This is caused by the shock waves released when an earthquake occurs. Ground shaking can in turn cause many secondary hazards. It can lead to ground failure and liquefaction – this refers to the way in which soil and loose materials can turn into a liquid-like substance and lose all its strength and cohesion. As a result, buildings may collapse, gas pipes may fracture, and fires may ignite. Ground shaking can also lead to landslides and rockfalls. In coastal areas, submarine earthquakes may cause tsunamis.
Page 19
The mass movements are Sliding and thumping, the weathering is mechanical, chemical, and biological.
Swash is the movement up the beach, whereas backwash is the movement down the beach.
Constructive waves consist of depositional waves, whereas destructive waves consist of erosional waves. Constructive waves have relatively low frequency (6-8 per minute), whereas destructive waves have relatively high frequency (10-12 per minute). Constructive waves have a long wavelength, and a low height, whereas destructive waves have a short wavelength, and a high height. Constructive waves have a swash greater than its backwash, where Destructive waves have a backwash greater than its swash.
Page 20-21
Hard rocks give rugged landscapes, whereas soft rocks produce low, flat landscapes.
They produce advancing coasts or retreating coasts, falling sea levels produce relict cliffs and raised beaches, rising sea levels are associated with fjords and rias (drowned river valleys).
Mangrove, coral, sand dune, salt marsh and rocky shore increase biodiversity through their microclimate, weathering and their indirect impact on human activities.
Page 23
Erosion occurs between the high-water mark and the low-water mark, the cliff is eroded backwards to create an indent (notch), as erosion continues the notch retreats further into the cliff, and the overhang becomes larger.
On a headland, due to wave refraction, energy is being concentrated on the sides of the headlands, creating caves. Overtime due to further erosion and weathering, the caves then go further back into the headland, and meet the cave at the other side which creates an arch. This arch, due to erosion, weathering and mass movements, collapses on itself creating a stack.
A spit is a beach of sand or shingle that is connected from the mainland to the ocean. It has a plentiful supply of sediment and often becomes curved as waves undergo refraction.
Page 24
Coral reefs and mangroves are both located in tropical environments. However, coral reefs are found in areas of clear water whereas mangroves are in estuaries and areas of muddy water.
Sand dunes are found in storm wave environments where there is a strong prevailing onshore wind, a large supply of sand and a large tidal range, so that a large expanse of sand can regularly dry out and be carried onshore by the winds. In contrast, salt marshes are found in sheltered areas behind spits and in river estuaries, where there are high levels of nutrients and oxygen, and the tide has a cleansing action on the salt marsh (removes debris).
Possible reasons for the lack of coral reefs off the west coast of South America are that the water is too cold (cold ocean currents) or that is does not have the right salinity levels (too hot, causing increased salinity due to high evaporation), or the water is too murky due to strong ocean currents lifting up sediments from the sea floor.
Page 26
Human activities in salt marshes are very varied e.g., building accommodation, hotels and other tourist developments, roads, industrial development etc. Many salt marshes offer a good site for trade. Some salt marshes have been drained to eradicate mosquitoes. The introduction of exotic species may lead to major changes in the salt marsh ecosystem.
Vegetation cover, diversity and canopy height all increase with distance from the shoreline. However, salt tolerance and tolerance to sand movement decrease rapidly at first, and then decrease more slowly.
Wind speed will be higher on the shoreline than at the back of the dunes. This is because the vegetation reduces wind speed both near the surface (winds are slowed down by tall grasses) and higher up (by the growth of shrubs, bushes and trees).
Page 27
Global climate change leads to increased temperatures which lead to increased ocean temperatures. More carbon dioxide in the oceans leads to acidification which damages coral and shell-forming organisms. The increase in temperature leads to a decrease in algae which leads to coral bleaching.
Mangroves are in low-lying coastal areas so are potentially in a good site for settlement, trade, tourism, transport etc. Wood can be used for building, burning, foraging and it has many industrial uses. Hence mangroves are vulnerable to human pressures.
Coral reefs attract many tourists because they are located in warm tropical areas, they are associated with clean ocean water, they occur near to the coastline, they have a large biodiversity, and they may be close to sandy beaches.
Page 28
Sand is used in the construction industry to make cement and concrete. River and coastal sand are coarser than desert sand and are better at binding in concrete and cement than desert sand. There has been a huge demand for sand especially in rapidly developing economies.
Human activities in salt marshes are very varied e.g. building accommodation, hotels and other tourist developments, roads, industrial development etc. Many salt marshes offer a good site for trade. Some salt marshes have been drained to eradicate mosquitoes. The introduction of exotic species may lead to major changes in the salt marsh ecosystem.
Reasons for the conservation of sand dunes and/or salt marshes include their biodiversity – both are extreme environments in which specialised organisms survive and both are important habitats for the reduction of natural hazards, e.g. they reduce the risk of flooding (salt marshes) and high wind speeds (and dunes) and they offer a recreational function, which is important for human well-being.
page 30-31
A conservation area may lead to major access roads being built and possibly a visitor centre, it could cause problems related to congestion and lead to land prices rising as less land is available for development.
Different land-users of the Soufriere Marine Management Area include residents of Soufriere, divers/snorkelers, conservationists, commercial fishermen, subsistence fishermen, yachting enthusiasts, tourists, hotel workers.
Fishing can damage marine ecosystems directly through over-fishing. Commercial fisheries require ports, and so there is habitat destruction to make way for ports. Aquaculture developments may lead to the escape of alien species, and there may be effluent from aquaculture farms. Recreational fishing may lead to litter and oil on beaches, and discarded fishing gear.
page 31-32
Tsunamis are very fast waves in open water hence there is very little time to give warning. The tsunamis are generally caused by earthquakes near tectonic plate boundaries. Many of these are located around the Pacific Ocean, so they are relatively close to land masses/islands. The places they are close to therefore get little warning of the impending tsunami.
Buildings can be made flood-proof by being raised up (on stilts so that flood water may pass under the building, or on raised foundations); important features e.g. water, gas, electricity can be provided in sealed-infrastructure; partial flooding may be allowed and important furnishings kept at higher elevations (upstairs floors).
The main causes of coastal floods are high wind speeds, storms, storm surges, tsunamis. These may be affected by high tides and, increasingly, human activities.
page 33-34
Hard engineering structures alter natural processes to reduce the potential for erosion of the coastline. They include groynes, sea walls, revetments, rock armour and cliff drains. In contrast, soft engineering refers to working with nature. Examples include: the maintenance of a mangrove forest to reduce the impact of tropical storms, beach nourishment/replenishment increases the size of a beach by using sediment dredged from elsewhere.
Integrated coastal zone management is an attempt to manage all aspects of a coastal system, e.g. marine areas, land, people and economic activities. It tries to balance protecting the coastline with its use by people and the economy. In contrast, a shoreline management plan (SMP) is an attempt to protect an area of coastline without leading to problems elsewhere. The coast is divided into sediment cells, i.e. natural units. Some areas may be allowed to be eroded whereas others may be given protection.
Cliff drainage removes water from rocks in the cliff. This reduces the risk of landslides. It is very cost-effective although in some cases the drains may become new lines of weakness. Revetments have a permeable design which absorbs much wave energy and allows water to pass through the structure but with a much reduced force. They are easily made but have a limited lifespan.
Page 34 (Overall questions)
Any of the various weathering processes that cause physical disintegration of exposed rock without any change in the chemical composition, e.g. Hydraulic action, abrasion, attrition, mass movements etc.
A biotic factor is living elements in an ecosystem, an abiotic factor is non-living elements in an ecosystem.
Contains a rich biodiversity.
Must be placed in a warm environment, sea surface temperatures of 17-33*C.
Traction (larger particles dragged along the seafloor), and saltation (smaller particles bounced along the seafloor).
Thermal pollution, which leads to a rise in the temperature of water, which therefore expels the algae from the coral leading to coral bleaching.
Sea walls: Large-scale concrete curved walls that are designed to reflect wave energy; Revetments: Porous design to absorb wave energy; Gabions: Rocks held in wire cages to absorb wave energy.
Page 34-35 (Exam-style questions)
Sliding and slumping are important types of mass moss movement that occur in coastal environments.
Isostatic changes are local changes in the level of the land relative to sea level whereas eustatic changes are global changes in sea level. Both can lead to a relative rise or fall in sea level compared to the land.
Coral reefs are mainly found in tropical regions, close to land (and islands) and mainly in the western parts of oceans. They are especially common in the western Pacific Ocean.
As distance from the shoreline increases, vegetation cover also increases. It also becomes taller and there is a greater biodiversity. Vegetation near the shoreline has to tolerate high salinity levels and high wind speeds whereas towards the back of the dunes both salinity levels and wind speed are much reduced.
Spits are formed due to longshore drift transporting sediment along a coastline. When there is a change in the shape of the coastline longshore drift continues to transport the sediment away from the shoreline. Wave refraction and/or secondary winds may cause the end of the spit to become curved and bend inwards towards the coastline.
Land-use zoning has a number of advantages. These include: it allows for a variety of activities in an area, it varies the employment opportunities in an area, it provides for activities and employment in different seasons, and it allows an area to develop a wide range of resources. However, there are also disadvantages. Only a small area may be given over to each land-use, people may have to travel a long distance to reach their land-use site, some areas e.g. marine reserves may be placed close to a conflicting land-use e.g. fishing, and some fish may move into the fishing area, pollutants from one area. Ex: fishing/yachting may be transported into nearby land-use zones e.g. marine reserves.
The advantages of hard engineering structures are that they can provide some protection against coastal erosion and/or flooding. Some of the methods are easy to construct e.g. sea walls, cheap e.g. rock armour, and easily replaced or repaired e.g. groynes. However, hard engineering structures can be expensive, may have a limited life span, and can lead to other parts of the coastline being eroded e.g. down drift from groynes. They may also be unattractive and can interrupt the natural flow of sediment.
Page 38
A fragile environment is one that is vulnerable to change and may find it difficult to recover from natural or human-induced changes e.g. tropical rainforest, deserts or tundra.
Tropical rainforests are considered fragile as they have infertile soils which are susceptible to soil erosion if trees are cut down.Deserts are considered fragile as the lack of rainfall makes regeneration difficult. Similarly, tundra and alpine areas are considered fragile as the low temperatures slows regeneration after a disturbance.
Two natural threats to fragile environments are drought and fires. Two human threats to fragile environments include global warming and land-use change (deforestation).
Page 39
Desertification is the spread of desert-like conditions into previously productive areas.
The potential causes of desertification are diverse and include population pressure (growth, in-migration), agriculture (grazing and cropping) and the removal of trees for fuelwood/building purposes. These either reduce vegetation cover or degrade the soil. With less vegetation cover, the soil is exposed and subject to wind or water erosion, thereby leading to desertification.
Much of the original forest cover in Europe and south-east Asia has been removed. There has also been widespread removal in parts of southern and central Africa. There has been less forest loss in South and North America and in parts of Russia.
Page 42
The decline in mean temperature peaked at over 0.3 ̊C in the first year following the eruption. The decline in temperature dropped quickly between 1992 and 1995, and then declined more slowly until 2005 although mean temperatures were still 0.1 ̊C lower some 14 years after the eruption of Mt Pinatubo.
The greenhouse effect occurs because greenhouse gases (such as water vapour, carbon dioxide and methane) allow short-wave radiation to pass through the atmosphere but trap a proportion of out-going long-wave radiation from the Earth. This leads to a warming of the atmosphere. It is a natural effect and essential for life on Earth.
Mean global temperatures decreased by about 0.3 ̊C between 1880 and 1910, and then an increase of 0.5°C to the 1940s, followed by a decrease of 0.2 ̊C to the 1950s, and finally an increase of about 1.1 ̊C since the 1950s.
Page 42-43
Deforestation leads to an increase in soil erosion due to greater rain splash impact. It also leads to a leaching of nutrients (minerals) from the soil, making the soil less fertile.
Deforestation leads to changes in the water cycle. With fewer trees, there is less interception, reduced infiltration, more overland run-off and increased risk of flooding. The amount of rainfall in the region will be reduced, and drought may become more common. Water quality is also reduced as the overland run-off carries more sediment into rivers and streams.
Deforestation can lead to increased risk of drought and fire since with fewer trees there is reduced interception and more overland run-off. Much of the water leaves the regions. Hence temperatures can become much higher (as they are not heating water vapour), and therefore there is a greater risk of drought. As vegetation dries out in the raised air temperatures, the risk of fire increases.
Page 44-45
- Sea levels are rising because (i) as the oceans warm, they expand (the ‘steric effect’) and (ii) as a result of increased air temperatures more ice and snow is melting, eventually getting into the sea, therefore leading to sea levels rising. In some areas the land is sinking (subsidence), therefore sea level relative to the land is rising.
- 0.3–1.2m
- Up to 2.4m
- Kivalina is very low-lying and vulnerable to sea level rise, coastal erosion, increased storm events and saltwater intrusion.
Page 46
Desalination is useful in combating desertification as it allows freshwater to be made from seawater. For countries with a coastline the sea is an almost inexhaustible source of water. However, the major disadvantage is that it is expensive so many low-income countries cannot afford it. In addition, for countries that are land-locked, there is no source of seawater unless they were to import it through other countries which would also be very expensive.
Trees protect, shade and fertilise the soil. The roots bind the soil together and help reduce soil erosion. They reduce wind speed, and so help reduce evaporation. They return nutrients to the soil, and their leaves cast a shadow on the ground, thereby reducing temperature.
Zero tillage refers to not ploughing the soil.
Page 47
One advantage of the Central Amazon Conservation Complex is its large size (over 50,000km2). However, it covers only a tiny part of the Amazon rainforest so does not provide much overall protection.
Some advantages of small-scale local projects are that they are more likely to be in tune with the needs of local workers and may develop plans that are related to very localised problems/solutions. However, one disadvantage is that they may only affect a small area/small number of people.
The main objective of Brazil’s Forest Code is for landowners to maintain a proportion of their land (80%) as forest.
Page 49
- Individuals could choose to buy electric vehicles rather than those that run on diesel or petrol. Individuals could also use public transport, such as the high-speed trains. In addition, they would be able to walk or cycle rather than using a car; eat less meat and dairy products; use alternatives to plastics; and/or switch to renewable sources of energy.
- China’s energy consumption is changing in several ways. It has expanded greatly as the country developed economically. However, the country’s economy is changing, and as services replace heavy industry energy consumption will decrease. In addition, there is less burning of coal and a greater use of renewables notably wind and solar. However, there are major developments in nuclear power and in hydroelectric power e.g. the Three Gorges Dam.
- The UK has made progress with attempts to reduce global climate change through improved public transport, more bus- and cycle-lanes and through less use of fossil fuels such as coal. However, its progress in climate change may have slowed down due to a lack of new policies and limited progress with carbon capture and storage schemes such as afforestation.
Page 49-50 (Exam-style questions)
C
A
An ‘indigenous population’ refers to ethnic groups who are the original/earliest known inhabitants of a region aka First People/Nation, Australian Aboriginal people.
An increase of 2°C could expand the range of areas that mosquitoes could breed in, and so spread the risk of malaria, and lead to an increase in malnutrition and dehydration, lead to an increase in heat stress and so lead to increased risk of death.
Two potential impacts of rising sea levels are increased coastal flooding, especially of low-lying areas, and seawater may also contaminate freshwater stores (saltwater intrusion).
There are many options that people can make to reduce their own contribution to climate change including: walking or cycling rather than using a car – this reduces emissions of carbon; eating less meat and dairy products – if demand for meat decreases and there are less cattle emissions of methane are reduced; switch to renewable sources of energy – this reduces carbon emissions; wear a jumper/use a blanket rather than turning the heating on/up.
Oceans are experiencing acidification due to increased carbon emissions over the last 150 years. Carbon is absorbed by seawater and gradually makes it more acidic.
Sedentarisation of nomads forces them to remain in one area rather than move over large areas. This increases the grazing pressure on the land and may lead to overgrazing, vegetation removal and desertification.
It is possible to have large conservation areas e.g. Central Amazon Conservation Complex which protect rare and endangered species. The Forest Code is a law that requires landowners in the Amazon to maintain a proportion of their land (80%) as forest. Some indigenous groups use many ways to use the rainforest sustainably. In the Yanesha Forestry Cooperative Project, farmers cut a strip of rainforest some 20–40m wide, farm it, and then let it recover. Others plant fig trees on degraded land. These attract birds and bats which bring in seeds from neighbouring forests. The birds and bats deposit the seeds in their droppings thereby helping forest to regenerate.
There are many ways of tackling desertification. For rich countries/countries with a coastline, desalination is an option. However, it is expensive and a network of pipes would be needed to transfer the water from a coastal desalination plant to the desertified areas. Groundwater is an option – but it is a non-renewable resource, especially in dry areas. In poorer countries, desertification could be tackled through reduction in livestock numbers but increasing their quality; use of indigenous species/those adapted to dry conditions/poor quality grazing may reduce pressure on vegetation. Arable farming could be improved by using crops adapted to dry conditions, use of fertilisers to improve soil quality, crop rotation, zero tillage and/or irrigation. It is also useful to maintain a tree cover where possible as trees protect, shade and fertilise the soil.
Page 52
Urbanisation is the increase in the proportion of people living in urban areas in a country. In contrast, counter-urbanisation refers to the movement from larger urban areas to smaller urban areas and rural areas.
In Tanzania between 1950 and c.2000 more people lived in rural areas than in urban areas. However, from the mid-1970s the growth of the urban population was faster than the growth of the rural population. Tanzania is currently experiencing rapid urbanisation. In contrast, the rural population in Thailand has remained larger than the urban population but they are predicted to be very similar by 2025. Urbanisation was relatively slow up until about the 1980s. Since c.1990 the rate of urban population growth has exceeded the rate of rural population growth, and urbanisation has been rapid. The UK has had a much larger urban population than rural population since the 1950s. The rural population has been decreasing and the urban population increasing and so the proportion of population living in urban areas has been increasing (urbanisation).
LLEDCs are the world’s poorest countries.
Page 53-54
- Reasons for rapid urbanisation include the belief that there will be better chances of employment, better paid jobs and more secure jobs in urban areas; better provision of education and health facilities in urban areas; better access to clean water and sanitation, health care and education.
- A megacity is a city with over 10 million inhabitants.
- Dhaka
- New Delhi
- Tokyo – 2%
Page 55
- Population density in Dharavi is about 500,000 per km2
- Congestion varies with days of the week, time of day, weather and the seasons. Congestion is greater on weekdays, especially during the peak flow times in the morning and evening, with more people travelling to and from work. Congestion is also related to school opening and closing times, although many students walk/cycle to school. Congestion may be related to festivals, large-sporting events and national holidays. By contrast, during the summer, congestion may decrease as more people walk/cycle to work and schools are closed.
- Poor people are less likely to be connected to a water pipe and so may not be able to access piped water. (In some cases, there may be a shared water pipe in a street.) Therefore, they must buy it from vendors (sellers) and must buy it in bottles, which adds to the cost. In contrast, wealthier people are connected to the network of piped water and so have easier access and cheaper water – even if they are metered.
Page 57
Accessibility refers to how easy it is to reach a place.
Industry in a city tends to be located in the inner city, along major transport routes, in edge-of-town locations and by deep-water ports.
The value of land varies in urban areas. Central areas are the most valuable. They used to be the most accessible parts of a city (to public transport) and had a higher concentration of shops and offices. Land values are also high along major routeways and by intersections – these areas are accessible for workers, consumers, deliveries etc. Out-of-town locations have become more valuable as new ring-roads (orbital routes) make them more accessible, and therefore attractive to prospective users.
Page 58-59
Air quality is likely to vary spatially (by area) and temporally (over time). For example, there are likely to be more vehicles in central areas leading to more emissions. There will also be higher concentrations near shopping centres, schools, industrial estates etc. There is also likely to be poorer air quality in the underground tube network, especially in the older deeper stations and lines. Air quality is likely to be lower during rush hour, and on weekdays rather than at the weekend.
An ecological footprint measures the amount of land needed to provide a population with the resources it consumes and to absorb its waste.
London has a high ecological footprint per person because it has a wealthy population and so their consumption of energy, water, transport, material and food is likely to be much higher than that of people who are less well off.
Page 61
One advantage of Dharavi’s location is that it is close to the financial and commercial core of Mumbai. One disadvantage of its location is that it is prone to summer flooding.
The informal economy is the unregulated, untaxed economy – it is sometimes called the ‘black market’.
Water pollution is a problem in Dharavi because there is limited access to piped water and so some people collect water from the Mahim Creek. However, this creek is also used as a toilet by many people and used to dispose of other waste materials including chemicals and industrial products. It also receives water from open sewers. Hence the water sources are heavily polluted.
Page 62
Greenfield sites are likely to be on the edge of town.
Redeveloping brownfield sites may make good use of disused land, it does not harm the environment and it may create jobs locally.
The disadvantages of developing greenfield sites include the destruction of habitats to make way for new developments. This reduces biodiversity and the provision of ecosystem services. It replaces permeable surfaces with impermeable surfaces – this may increase the risk of flooding and lead to a deterioration of water quality.
Page 64
The linear city has a large volume of inputs (e.g. food, energy and goods) and a large volume of outputs leading to many organic and inorganic waste materials leading to emissions of CO2, SO2 and NO2.
The circular city is more sustainable because there are fewer inputs of energy, food and goods; there is more recycling of materials, and there is less pollution and waste produced.
Two social needs in the sustainable city are access to education, so that everyone can achieve their potential, and providing affordable medical provision for everyone.
Page 64-65
Existing residents may prefer that no further development occurs as it will lead to pollution, congestion, noise etc. However, first-time buyers may view it as an opportunity to buy a house (own a property) and to have somewhere to live and not to be paying rent to a landlord.
An example of a private stakeholder is the residents whereas a public stakeholder could be the Stockport Metropolitan Borough Council.
It has proved difficult to reach agreement on how to develop urban areas sustainably as different users have different perspectives/aims.
Page 65 (Exam-style questions)
B
A
B
Pull factors (in relation to urbanisation) are the positive aspects of urban living that attract migrants. Push factors are the negative aspects of rural living that make a person want to leave.
Compact cities minimise the amount of distance travelled, use less space, require less infrastructure, are easier to provide a public transport network for, and reduce urban sprawl.
Industry is located in different zones in cities for different reasons. Early industrial areas were in the inner city to be close to transport routes (e.g. railways and canals), the market (city centres) and the workforce. Some industries require specific locations e.g. close to a river for water e.g. large steel works, or along transport routes (as the workforce became more mobile and goods were transported by lorries). More recently, industrial areas have developed on the edge of town where there is more land available and it is cheaper than more central areas.
A ‘squatter settlement’ is a settlement which has no formal government recognition i.e. it is an illegal settlement and can be demolished without warning.
Counter-urbanisation may occur in many MEDCs because large cities are seen as being too expensive, unhealthy, with a poor environment and high crime rates. In contrast, smaller settlements are considered to be healthy, safer, have a sense of community and house prices there are cheaper.
Urban areas may be made more sustainable by using resources in a sustainable way; conserving non-renewable resources; minimising waste – cutting use of non-renewable resources; providing affordable housing and medical provision; making cities more compact; providing access to education for all; creation of a healthy environment free from pollution; providing a range of jobs for people, and making it possible for them to get to work; ensuring that housing and employment are close together; empowering people and allowing them to make decisions in local politics.
