Case study theme 2

Question 1

For a named river you have studied, explain why flooding occurs ?

Answer 1

Named river: river Valency (on the northern coast of Cornwall, South West of England)
- Deforestation, trees removed from valley sides => less interception => more surface runoff => water reaches river quickly
- Confluence just before Boscastle with river Jordan => lots of water joined at once => high discharge level during periods of heavy rainfall
- Urbanisation, (concrete, brick, steel) impervious surfaces => water cannot infiltrate => Increases surface run-off => water reaches river quickly & flood

Question 2

For a named river you have studied, describe the impacts of flooding ?

Answer 2

Named river: river valency
- Gov had to spend 10m GBD to build defences to ensure that flood is not going to happen again => affect the local economy & public spending => lower SOL
- Increase in premiums paid by local residents to insurance in future due to greater risk of property being damaged
- Less money for local shops and services => main function is tourism => less tourists travel to dangerous destination

Question 3

For a named river you have studied, describe how it is managed to reduce the risk of flooding ?

Answer 3

Named river: River valency
- Increase channel size (channelisation); make river channel deeper => increases the amount of discharge river can carry when joined by the river Jordan, northeast of river Valency
- Afforestation, increase interception as trees are planted to the valley sides => decreases surface run-off & increase infiltration of water to soil
- Bridge built over the river rather than into the river => not slowing down, disturbs the flow of the river, prevent lots of discharge accumulated behind the bridge

Question 4

Describe the main features of an oxbow lake and explain its formation. You may use a labelled diagram or diagrams.

Answer 4

• A curved, horseshoe-shaped lake forms on a river’s flood plain; surrounded by flat land & may gradually become shallow forming a marsh
• When river goes around a meander, most water is directed to the outside bend => river velocity on outside of meander is high => giving it energy to carry greater load
• With load by corrasion & hydraulic action => river laterally erodes the outside bank, form steep river cliff
• On the inside bend, river flow more slowly => not enough energy to carry material => deposition occurs forming a slip-off slope
• With erosion on the outside bend and deposition on the inside => the meander gets more sinuous; eventually the meander’s neck is very narrow
• River breaks through neck at time of high discharge to take shorter course
• Deposition at the bend in the channel => seal the bend form ox-bow lake, may dry up over time

Question 5

Draw a labelled diagram to show the features of a waterfall. Explain how a waterfall is formed.

Answer 5

• Waterfall occurs in the upper course of a river, where more resistant rock (limestone) at Ban Gioc waterfall in Cao Bang, Vietnam overlies less resistant rock (erodes much quicker)
• Mentioned hydraulic action, abrasion & corrosion as erosions processes & define them (psr)
• Erosion a lot faster in less resistant rock => soft rock retreats due to the splashing water and eddie currents in the plunge pool; undercuts hard rock above, eventually created an unsupported overhang.
• Continued erosion increases the size of the overhang & eventually collapses into plunge pool due to gravity
• Due to repeated collapses, the waterfall gradually retreated upstream, forming steep sided valley on both side called gorge.

Question 6

Describe the main natural features of a delta and explain how it is formed. You may use a labelled diagram or diagrams

Answer 6

• Delta is a low-lying landform found at the mouth of the river
• Usually flat & triangular/fan-shaped; often contain marshes, mudflats & wetlands due to poor drainage & very fertile soil
• When a river carrying a large amount of sediment entering a sea/lake => river loses velocity
• Fine clay particles stick together (flocculation) => form larger, heavier particles that sink & are deposited
• Over time, continuous deposition builds up sediment to sea level & vegetation grows on it to trap soil together forming a delta
• The main channel is forced to divide into smaller channels called distributaries

Question 7

Describe the opportunities provided by a named river you have studied for people who live close to it ?

Answer 7

Named river: river Valency
- Tourism, river flows through steep-sided scenic valley before reaching Boscastle harbour, north coast of Cornwall=> attract tourists => create jobs & income
- Water supply, provides local freshwater source => support daily needs e.g washing, sanitation, small-scale use
- Agriculture & farming, river deposits alluvium => sediments rich in nutrients (fertile soil) => high-yield crops; water supply for livestocks

Question 8

Volcanic eruptions are another tectonic hazard. For a named volcano you have studied, explain the causes of a volcanic eruption ?

Answer 8

Named volcano: Soufriere Hills volcano
- Occur in south of the island Montserrat by movement at a destructive (convergent) plate boundary & describe the engine that cause movement
- Atlantic plate subducted beneath the Carribbean plate
- As the denser oceanic plate sinks into the mantle, it melts due to high temperature & pressure => forming magma beneath Earth’s surface
- Hot magma is less dense => rises through cracks in the Earth’s crust
- Magma is viscous & contains large amounts of dissolved gases => gases are trapped & pressure build beneath surface
- Eventually, pressure is too great => magma is forced upward & erupts explosively releasing ash, volcanic gases & pyroclastic material

Question 9

For a named area which you have studied, explain the causes of an earthquake ?

Answer 9

Named area: Tohoku (Tohoku earthquake 2011, magnitude 9.0)
- Occur along Japan trench (east of Japan), by movement at a destructive (convergent) plate boundary & describe the engine that cause movement
- The Pacific plate moving towards & forced beneath the Okhotsk plate (part of North American) as the oceanic plate is denser & sinks
- Friction causes the plates to become stucked together & pressure builds up as plate continues to move while stuck
- When pressure is too great, plates slip past each other & release seismic waves rapidly
- Sudden release cause violent ground shaking produce earthquake, formed very large fault area beneath sea bed

Question 10

Describe the impacts of an earthquake on a named area you have studied ?

Answer 10

Named area: Tohoku (Tohoku earthquake 2011, magnitude 9.0)
- Loss of life & destruction of settlements, earthquake & resulting tsunami killed around 18000 people & communities swept away by tsunami waves
- Damage to infrastructure: roads, railways, ports & airports were destroyed => disrupt transport and communication
- High costs of damage & rebuilding, caused approximately $235 billion; factory closed, disrupted global supply chain => hinder growth

Question 11

For a named example you have studied, describe the problems caused by a volcanic eruption ?

Answer 11

Named area: Montserrat (Soufriere Hills volcano)
- Destruction of settlement & infrastructure; capital city Plymouth, south-west of Montserrat buried under thick layer of ash & pyroclastic material => destroy homes, gov buildings
- Loss of life & displacement of people, 19 people killed in 1997 due to pyroclastic flows & 2/3 of population migrated => overcrowding in other areas
- Economic decline, agriculture was destroyed as ash covered farmland & livestock died; tourism collapse due to safety concern => unemployment

Question 12

For a named area you have studied, explain what has been done to reduce the impacts of earthquakes ?

Answer 12

Named area: Tohoku (Tohoku earthquake 2011)
- Gov introduced strict planning regulations, building needs earthquake-resistant features e.g shock absorber, deep foundation
- Strengthened earthquake-early warning system; seismic sensors detect seismic P-waves & send alerts seconds before stronger shaking arrives => can react
- Preparedness & education to people in Tohoku region, north-east of Japan through regular earthquake drills & evacuation plan

Question 13

Explain why people live close to a named volcano you have studied ?

Answer 13

Named volcano: Soufriere Hills volcano (Montserrat)
- Fertile volcanic soil, ash breaks down into minerals => allowing farmers to grow crops successfully => income
- Employment opportunities in tourism, attract visitors to volcanic landscape & monitoring centre => income for locals
- Geothermal energy for electricity & water due to heat close to the surface => reliable & cheap energy source => create local jobs

Question 14

Describe and explain the conditions which lead to the development of a coral reef ?

Answer 14

• Warm water, usually between 23°C to 27°C => algae inside coral polyps photosynthesise efficiently => energy for coral growth
• Shallow water, less than 50m deep => sunlight can penetrate => photosynthesis of algae => energy to build CaCO3 skeleton
• Clear, unpolluted water & little sediment; muddy water blocks sunlight prevents coral growth => form away from river mouths
• Good supply of oxygen in water => get energy from respiration => for growth & repair (build CaCO3 skeleton)

Question 15

For a named coastal area you have studied, describe the impacts of a tropical storm ?

Answer 15

Named coastal area: Phan Thiet e.g Typhoon Usaghi
- Torrential rain => widespread flooding in low-lying coastal wards => disrupt transport, damage houses & affect agriculture
- Very strong winds => damage houses with lightweight roofing, uprooted trees & brought down electricity lines
- Storm surge, pushed seawater onto low-lying coastal areas e.g Mui Ne, northeast of Phan Thiet => coastal flooding & beach erosion => damage infrastructure

Question 16

For a named coastline you have studied, describe the hazards resulting from natural processes and their impacts on people ?

Answer 16

Named coastline: Phan Thiet; Chosen hazard: coastal erosion
- Damage to homes & property, coastal areas e.g Mui Ne, northeast of Phan Thiet, waves remove bead => buildings exposed to wave attack
- Affects tourism industry due to beach narrowing along Mui Ne reduces space for tourists & damaged resorts => lose income
- Damage local infrastructure, coastal road, walkways & fishing facilities => disrupts transport & lost of income by fishing

Question 17

For a named area of coast you have studied, explain what is being done to manage coastal erosion ?

Answer 17

Named area of coast: Phan Thiet
- Sea dykes along vulnerable coastal sections e.g Mui Ne, northeast of Phan Thiet => absorb & reflect energy => protect hotels, roads & tourists
- Rock armour (tetrapods) => break incoming waves & reduce their energy before reach land; tightly held together (no regular repair)
- Offshore breakwaters (concrete barrier offshore) => waves break before reaching beach => reduces wave energy & encourage deposition

Question 18

For a named area of coast you have studied, describe the benefits for people of living on or near the coast ?

Answer 18

Named area of coast: Phan Thiet
- Employment in tourism, e.g Mui Ne, northeast of Phan Thiet attracts lots of tourists due to sandy beaches & warm climates => create jobs & income
- Fishing & marine resources from East sea, jobs in fishing, seafood processing => sales & local consumption
- Recreational & peaceful lifestyle, sea breezes, scenic views & leisure beach activities => improve quality of life

Question 19

Another area of natural vegetation is a mangrove swamp. Describe the main characteristics of mangrove swamps and explain why they develop in some areas ?

Answer 19

• Are coastal wetlands found in tropical & subtropical regions, consists of salt-tolerant trees & shrubs in waterlogged soils with prop roots & aerial roots rise above mud & dense vegetation
• Warm tropical climate, high temp => mangrove trees grow throughout year => increase plant productivity & rapid growth
• Low-energy coastal environment e.g sheltered bays & estuaries => sediments deposit => create soft, muddy surfaces for mangrove to grow
• Brackish water, as other plants will grow more dominate in freshwater & mangroves are adapted for high-salinity

Question 20

Describe the features of a sand spit and explain how it has been formed. You may include a labelled diagram.

Answer 20

• A long narrow ridge of sand/shingle extends out from coastline into sea, end of spit is curved & behind spit often has mudflats/salt marshes
• Prevailing wind pushes waves coming to the coast at an angle => swash moves up the beach at an angle
• Backwash, however, drains straight back down => transport sediment along the coastline in a zig-zag pattern
• When coastline changes direction, LSD continues deposit sediment in same direction out into sea
• Deposit builds up above water level forming a spit that grows longer over time
• Secondary wind pushes wave coming from another angle => curve the end of spit
• Sheltered area behind spit => low-energy & fine sediments settle with vegetation growth form salt marshes

Question 21

Explain how bays and headlands are formed on a coast. You may use a labelled diagram or diagrams.

Answer 21

• Form where there are alternating bands of hard & soft rock at right angles to sea (discordant coastline)
• Soft rock eroded more quickly than hard rock through hydraulic action & abrasion (define for psr) => over time forming an indentation in coastline known as bay
• Hard rock eroded slower remains protruding out to sea forming a headland
• Water around headland is shallow => waves slow down due to friction while the rest of the waves continues moving fast in deeper water => waves bend towards the headland (wave refraction)
• Wave energy is concentrated in the headland => low-energy wave into bays => deposition & beach form

Question 22

Explain the formation of a cliff and wave-cut platform. You should include a labelled diagram or series of diagrams.

Answer 22

• Formed where coastline made of more resistant (hard) rocks
• Wave erosion by hydraulic action & abrasion (define for psr) is concentrated at the base of the cliff forming an indentation called wave-cut notch
• Notch gets larger due to repeated erosion create an overhang protrude outward
• As the overhang gets larger, it collapses due to gravity as its weight can no longer be supported
• Repeated collapses of overhang => cliff gradually retreated backward leaving an area of gently-sloping rocks extends out to sea called wave-cut platform (can exceed 0.5 Km as waves can’t reach that far)

Question 23

Explain the formation of an arch and a stack at the coast. You should include a labelled diagram.

Answer 23

• Needs a headland of more resistant (hard) rock protruding out to sea
• Erosion by hydraulic action & abrasion (define for psr) concentrates at the line of weakness (cracks/faults) forming wave-cut notch
• Repeated erosion => notch gets larger forming a cave
• Continued erosion deepens cave further into headland & if caves develop on both sides => eventually meet forming an arch going through headland
• Roof of the arch is weakened by marine erosion below and weathering from above => roof collapses due to gravity as its weight can no longer be supported
• Form an isolated pillar of rock called stack that can be further eroded and weathered into a smaller feature, stump

Question 24

For a named area of tropical rainforest you have studied, explain why deforestation has taken place ?

Answer 24

Named area of tropical rainforest: Borneo
- Population growth & migration increases demand for land, people move from densely populated islands e.g Java west of Indonesia to Borneo north of Indonesia
- Mining activities for gold & coal; forests cleared for open-cast mining & build transport infrastructure
- Commercial logging of valuable hardwood trees e.g teak & mahogany => export to international markets => open areas further into the forest

Question 25

For a named area of tropical rainforest you have studied, describe the impacts of deforestation on the local people

Answer 25

Named area of tropical rainforest: Borneo - Loss of traditional livelihood, indigenous groups e.g Dayak people, live in central & western Borneo rely on forest for hunting, shifting cultivation & collect forest products - Displacement of indigenous communities; logging companies take ancestral land => loss of traditional culture - Soil erosion, tree roots no longer hold soil together => soil wash to river => loss of soil nutrients & flooding

Question 26

For a named area of desert you have studied, explain why the climate is hot and dry ?

Answer 26

Named area of desert: Sahara - Location near Tropic of Cancer (23.5° N of equator) => air sinks after rising at Equator => warms & dries as it sinks prevent cloud formation & rainfall - Affected by north-east trade winds blow from land rather than oceans => carry little moisture reduce humidity & rainfall e.g in Egypt & Sudan, eastern Sahara - Clear skies due to few cloud formation => strong solar radiation reaches the ground during day => high daytime temp (40°C)

Question 27

For a named area of hot desert you have studied, describe and explain the characteristics of its natural vegetation ?

Answer 27

Named area of hot desert: Sahara - Sparse & widely spaced vegetation e.g Northern Algeria & Libya, north of Sahara, as rainfall below 100 mm per year => reduce competition for scarce water - Deep & extensive root system, deep => reach groundwater supplies, wide network => absorb water before evaporates - Thick waxy surfaces & spines reduce water loss through transpiration (smaller surface area) - Seed remain dormant for years, only germinate after rainfall => survive droughts

Question 28

For an area you have studied with an equatorial climate, describe and explain the climatic characteristics.

Answer 28

Area: Borneo - High temperatures (26-28°C) with little seasonal variation; near Equator => sun at more direct angle all year => intense & constant solar radiation - High annual rainfall of over 2000 mm per year e.g in Saba & Sarawak, north of Borne; strong heat => rapid evaporation & rising moist air => rainfall - High humidity, often above 80%; dense vegetation & high temp => large amount of evaporation & transpiration => uncomfortable, humid

Question 29

For a named area of tropical rainforest you have studied, describe and explain the characteristics of its vegetation ?

Answer 29

Named area of tropical rainforest: Borneo - Layered structure, distinct layers: emergent, canopy, under canopy, shrub layer => due to intense competition for sunlight => plants grow at different heights - Evergreen broad leaves with drip tips => rainfall runoff quickly (2000-3000 mm per year) => prevent rot/fungal growth - Buttress root => provide support for very tall trees & absorb nutrients in the topsoil - Lianas & epiphytes grow on tree trunks => reach sunlight above the under canopy => survive

Question 30

For a named area of tropical rainforest you have studied, describe the impacts of deforestation on the local natural environment

Answer 30

Named tropical rainforest: Borneo - Loss of biodiversity, forest clearance destroy habitats of endangered species => reduce population number => risk of extinction - Soil erosion, logging in areas like Central Kalimantan, south of Borneo => soil easily washed away by rainfall => loss of nutrients (infertile soil) - River & water pollution, soil washed into rivers => sedimentation => muddy water reduce sunlight & oxygen