Flashcards in Crowded coasts Deck (48):
Physical factors that create different coastal environments?
-Rock types and erosion create: cliffs and stacks.
-Where big rivers flow into the sea, wide tidal estuaries are formed
-Coastal erosion creates sheltered inlets and deep natural harbours
-Floodplains are wide, flat valley floors regularly flooded. Deltas form at river mouth when sediment is deposited by the river faster than the sea removes it.
-Beaches are formed where the sea deposits eroded material
-Coastal ecosystems are valuable natural environments, important breeding grounds for fish and shellfish.
What encourages different types of development?
-Dramatic scenery of coastlines e.g Jurassic Coast
-Natural harbours for import and export of raw materials attracts industry
-Estuaries allow easy access for ships, encourage port development
-Alluvium deposited on floodplains make soil fertile
-Some coastal ecosystems have a high biodiversity which attracts fishing and tourists.
-deep water access for boats
How has development led to coastal population growth?
-Accessibility, fertile soil, equable climate, dramatic scenery.
-Fishing, tourism and port development create employment opportunities.
-Land is flat so more property development and businesses
Three land use models
-Burgess: settlement growing out in concentric zones from the centre
-Hoyt:has concentric zones but adds sectors that grow along linear features
-Harris and Ullman: multiple nuclei of different land used
How does coastal development distort shape of a land use model?
Sea limit growth in that direction. Linear zones develop along the sea front
How does coastal development distort accommodation of a land use model?
Larger hotels based on the sea front, closest to the Tourist Business District (TBD). Smaller hotels further away from the TBD-Multiple nuclei.
How does coastal development distort open spaces of a land use model?
Parks and pleasure gardens on the seafront
How does coastal development distort entertainment of a land use model?
Piers want to attract tourists, so they locate where tourists gather at the sea front.
4 different types of conflict
Tourism, overfishing, aquaculture and industrialisation
How does tourism create conflict?
-Conflict between tourists and locals over traffic congestion, parking and noise.
-Environmental impact as increased tourism means more road building and construction of other amenities. Built on ecologically important land. Conflict with tourists and people protecting ecology of the coast.
How does overfishing create conflict?
-Rapid decline of fish populations
-Efforts to conserve fish conflict with fishing industry
-Limits to fishing could lead to job losses
How does aquaculture cause conflict?
-Affordable fish and shellfish cultivated in 'fish farms'
-Conflict with producers and environmentalists.
-High levels of fish decrease dissolved oxygen levels in water lead to death of fish and plant life.
-Diseases spread from farmed fish
How does industrialisation cause conflict?
-Ports expanded which means coastal ecosytems under threat-flat land good for construction
-Conflict between industry exploiting advantages of locating near the coast, and people trying protect SSSI.
-Pollution from industrial waste affects swimmers and marine life. Conflict between coastal industries and tourists and environmentalists.
What are the inputs, processes and outputs of coasts?
-Inputs: sediment from cliffs eroded and transported offshore by waves
-Processes: wave action, tidal movement, erosion, transportation and deposition
-Outputs: sediment washed out to sea
What are coastal sediment cells?
-Lengths of coastline that are self-contained for the movement of sediment
How are waves formed?
-Wind blowing over surface of sea, friction between wind and surface gives circular motion
-Effect of wave depends on height, height affected by wind speed and fetch
-As waves approach shore they break, friction with seabed slows bottom of waves making them more elliptical. Crest of waves rises then collapses.
Two types of wave?
-Constructive: low frequency. Low and long. Powerful swash carries material up beach and deposits it.
-Destructive: High and steep, high frequency, strong backwash removes material
Sub-aerial processes along a coastline
-Weathering: weakens cliffs making them vulnerable
-Throughflow: flow of water through cliffs (throughflow) and the flow of water over land (runoff) can make cliffs unstable causing landslides.
-Mass movement landslides
5 main ways waved erode the coastline
-Abrasion/corrasion: rock/sediment grind against rocks and cliffs.
-Hydraulic action: Air in cracks in cliffs compressed when waves crash in. Pressure exerted breaks off rock pieces.
-Quarrying: Energy of waves breaks against cliff detaching bits of rock
-Corrosion/solution:Soluble rocks gradually dissolved by seawater
-Attrition:Bits of rock smash against eachother and break into smaller bits
5 factors that affect the rate a stretch of coastline is eroded.
-Width of beach: Beaches slow down waves so wide flat beaches will protect cliffs more than, narrow steep.
-Breaking point of waves:Break directly at cliff causes most erosion vice versa.
-Aspect: faces dominant winds and wave direction, erosion will be faster
-The fetch of wave:waves with large fetch, much higher and steeper/more erosion
-Rock type:Hard rocks like granite much more resistant to erosion.
How does current transport sediment?
-Move material along coast-longshore drift
-Swash carries sediment up beach parallel to prevailing wind. Backwash carries sediment down beach at right angles.
Physical causes of flooding?
-Hurricanes reduce atmospheric pressure on sea surface causing it to rise (storm surge)
-Strong onshore winds:force water to higher levels, allowing waves further inland
-High rainfall causes high river discharge
-Tidal currents and surges funnelled into a coastal bottleneck forcing sea levels higher.
Human activity that intensifies coastal flooding
-Management of river systems: Dams trap sediment so reduce the amount deposited at the river's mouth, causing deltas and salt marshes to shrink, less protection against storm surges.
-Management of coastal systems: alter sediment movement, reducing the amount of protective beach material along the coast.
-Building on coastal lowlands:restricted sediment supply to protective beaches and marshes.
-Reclamation of coastal lowlands: Draining land to reclaim causes land to shrink to become lower than sea level.
What causes eustatic sea level change and the causes (global)?
-Change in volume of water in the sea, change in shape of ocean basins.
-Tectonic movements of earths crust alter shape
-Changes in climate: melting of ice sheets/water to expand
-Decrease in temperature/more precipitation as snow/more water stored in glaciers and so reduces volume of sea.
What causes Isostatic sea level change and the causes (local)?
-Vertical movements of land relative to the sea/downward movement of land causes sea levels to rise locally, uplift of land causes sea levels to fall.
-Tectonic uplift occurs mostly at plate boundaries
-Subsidence of land due to shrinkage after abstraction of groundwater
Impacts of sea level rise?
-More frequent and more severe coastal flooding: Flooding of low-lying area increased
-Submergence of low-lying Islands: lots of low-lying islands disappeared, and more at risk.
-Changes in coastline: sea levels rise the coastline changes-Islands created and area of land is decreased
Further impacts of sea level rise?
-Damage to coastal infrastructure
-decrease in tourism
-decrease in agriculture
-loss of homes
Four options of coastal management
-Hold the line: maintain existing coastal defences
-Advance the line: build new coastal defences further out to sea than existing ones
-Do nothing: build no coastal defences, deal with effects
-Retreat the line: build no coastal defences, move people away from the coast.
9 different types of hard engineering
How a sea wall works, cost and disadvantage?
-Reflects waves out to sea, acts as a barrier for flooding
-Expensive to build and maintain
-Strong backwash eroding under wall
How a revetment works, cost and disadvantage?
-Slanted structures on the foot of a cliff. Waves break against them, absorbing wave energy.
-Expensive to build, cheap to maintain
-Create strong backwash
How Gabions works, cost and disadvantage?
-Rock-filled cages, built at foot of cliff, absorb wave energy
How a riprap works, cost and disadvantage?
-Boulder piled along the coast, absorbing wave energy
-Shift in storms
How a groyne works, cost and disadvantage?
-Fences built at right angles to the coast. trap beach material deposited by longshore drift, creating wider beaches. Greater protection from erosion
-Starve down-drift beaches of sand
How a Breakwater works, cost and disadvantage?
-Blocks or boulders that force the waves to break offshore.
-Damaged by storms
How a earth bank works, cost and disadvantage?
-Mound of earth act a barrier
-can be eroded
How a tidal barrier works, cost and disadvantage?
-Built across river estuaries, retractable that can be raised to prevent flooding
How a tidal barrage works, cost and disadvantage?
-Dams built across river estuaries, water trapped behind dam at high tide, generates electricity. Controlled release of water at low tide generates electricity, prevents flooding.
-disrupt sediment flow, increasing erosion elsewhere.
6 types of soft engineering
-Land use management
What is beach nourishment
-sand and shingle added to beaches from elsewhere, creates wider beaches, reduces erosion
What is beach stabilisation?
-reducing slope angle and planting vegetation, sticking stakes and old tree trunks in beach stabilising sand, creates wider beaches.
What is dune regeneration?
-sand dunes created or restored by either nourishment or stabilisation. Act as a barrier between land and sea, absorbing wave energy
what is land use management?
-vegetation on dune easily trampled on which stabilise dune, walkways, fenced off areas prevent people accessing dunes, reducing vegetation loss.
what is creating marshland?
-planting appropriate vegetation, stabilising sediment, stems and leaves reduce power of waves. Reducing erosive power and how far waves reach inland
what is coastal realignment (managed retreat)?
-Breaching existing an existing defence allowing sea to flood land. Overtime, vegetation will colonise the land and become marshland.
Why is soft engineering more sustainable than hard engineering?
-Hard engineering: expensive, disrupts natural processes
-Soft engineering: cheaper, less money to maintain them. Integrate with the natural environment as it creates marshland and sand dunes, important for for coastal plants and animals. Low economic and environmental impact
What is a shoreline management plan (SMP)?
-How a coastline in one sediment cell should be managed. Developed by local authorities . All local authorities in one sediment cell cooperate when planning, so defences in one area dont increase erosion in the adjacent area in the same cel