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36 Cards in this Set
- Front
- Back
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What is a coastal zone? Why are coastal zones popular? |
The transition zone between the land and sea Fishing, trade, resources such as oil, residential, recreational, tourist |
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Describe the differences between hard rock coasts and soft rock coasts, using examples. |
Hard rock -Land's end -more resistant to eroding -igneous and sedimentary -high, steep and rugged -bare cliff faces
Soft rock -Walton, the Holderness -clay and shale -less resistant to erosion -less rugged and not so steep -slumping
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Describe the three main types of erosion. |
Hydraulic action -water is forced into cracks in the rock, compressing air -when wave retreats air is forced out, splitting rock
Abrasion -loose rocks and sediment are hurled at the cliffs by waves, wearing and chipping the cliff
Attrition -loose sediment and rocks knocked off the cliff collide with others in the sea and become smaller and rounder |
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Describe the process of a wave cut. |
-Waves concentrated at base of cliff -Abrasion creates wave cut notch -Cliff overhang -Collapse -Resulting debris at base protects cliff from further erosion -Attrition over years erodes protection and cliff is again exposed -Repeating process, cliff retreats inwards -Smooth level of rock is left (wave cut platform) to show where cliff originally was |
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Describe how coastal landforms are created. |
-Hydraulic action weakens joints and fissures -Large crack -Cave formed by hydraulic action and abrasion -Cave grows -Arch -Arch collapses, leaving a stack -Stack erodes into stump |
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Describe the differences between concordant and discordant coastlines. |
Concordant -layers of rock are parallel to coastline -Lulworth -Coves (oval shaped bay with narrow opening to sea)
Discordant -layers of rock are perpendicular to coastline -headlands and bays
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Describe the difference between joints and fissures. |
Joints are small, natural cracks. Fissures are larger cracks caused by past tectonic movement. |
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What does the size of a wave depend on? |
-Wind strength -How long the wind blows for -Fetch (area the wind blows over) |
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How do waves occur? |
-Wind tugs surface of water, causing wave shape to move -Particles move in circular motion and return to starting point -In shallower water, wave is distorted until it breaks -After break, not only energy but water that moves forwards -Swash and backwash |
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Describe the differences between constructive and destructive waves. |
Constructive -Summer -Spilling waves -Long wavelengths and low amplitudes -Strong swash -Transport sand up the beach -Sand is deposited as a beach berm or bank
Destructive -Winter (when strong winds and storms are more common) -Larger amplitudes and smaller wavelengths -Plunging waves -Strong backwash -Erode sand from beach -Steep beach profiles -Sand carried by underwater rip current -Sand deposited out at sea, causing offshore bar -Strong currents -Come in quick succession |
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What is an underwater rip current? |
After a wave breaks, the next incoming wave arrives so quickly that its backwash has to flow under an incoming wave |
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What is longshore drift? |
When waves break at an angle, rather than parallel to it, sediment is moved along the coast. The sediment is dragged down by backwash by pushed along the coast in the swash. As the prevailing winds are usually in one direction, longshore drift is too. |
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What is a spit and how is it formed? |
A long, narrow ridge of sand and shingle which is projected into the sea from the coastline.
-Longshore drift transports beach material -Spits form in shallow, sheltered water where there is a change in direction of coastline -deposition and accumulation of material -Larger material deposited first due to reduction of energy -Finer material deposited, builds up rest of spit
-Change in wind direction could result in recurved spit -If growing across an estuary, length of spit is restricted by river erosion -Salt marsh may form behind spit |
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What is a bar and how does it form? |
A ridge of sand and shingle which has joined two headlands, cutting off a bay.
-Spit grows across a bay -Behind bar, lagoon is created as water is trapped -Lagoon fills with deposition over time |
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What is a tombolo and how does it form? |
A ridge of sand and shingle joining a mainland to an island. -Spit continues to grow until it reaches an island, creating a 'bridge' |
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Describe the properties of plants that grow on beach sand. |
-Tough -Long roots to hold them in place in strong winds -Tough, waxy leaves to stop them getting sand blasted -Survive being sprayed with saltwater |
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Describe the effects of rising sea levels on coastal flood risk. |
-Sea is warming up and expanding -melting ice caps cause sea levels to rise -Global warming causes sea levels to rise -17% of Bangladesh could be flooded if the sea rises by 1 metre -London and Essex in danger as they are low lying -Many coral islands (i.e. in the Pacific) could disappear underwater |
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Describe the impacts of increasing flood risks. |
-Gravity causes high tides twice a day -Spring tides (exceptionally high tides) happen a few times a year -Flood risk increases in spring tides -Spring tides and large waves make sea higher -Spring rides and waves combine with low air pressure to form storm surges and sea levels rise -Storm surges caused by hurricanes, global warming will increase hurricanes -Destructive storms, such as Storm Sandy in America 2012, could becomes 1 in 20 year events by 2050 whilst they are currently 1 in 100 year events |
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Describe the impacts of rising sea levels on erosion and deposition. |
-Balance of erosion and deposition will change due to increased sea levels and storms -Spits and beaches etc. may erode faster and become submerged -A sea level rise of just 50cm would make UK coastal defences useless -Only option would be to build higher defences or abandon some areas to sea |
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Define weathering. |
the breakdown of the rocks where they are. Rocks are weakened by being chemically attacked or mechanically broken down. |
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Define mass movement. |
the movement of materials down a slope, such as rock falls, landslides or cliff collapses |
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Give examples of marine processes. |
Hydraulic action Abrasion Cliff foot erosion (They make the cliff steeper) |
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Give examples of subaerial processes. |
-Weathering -Freeze thaw action -Solution -Rotational slumping -Rotational sliding -Cliff face erosion (rainwater)
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Give an example of how humans actions cause erosion. |
Building on the cliffs adds weight and weakens the cliffs |
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Why do erosion rates differ between locations? |
-resistance of rocks -wave energy/fetch -weathering and mass movement |
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Describe holistic coastal management. |
-Some places are protected if they are worth it, whilst others aren't -Cost benefit analysis -Defences may cause erosion somewhere else -Climate change will bring rising sea levels -May be better for environment -Takes opinions of different stakeholders -Economic costs -Benefits now and in future |
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Talk about the ICZM. |
-Integrated coastal zone management -Local councils set up defences -SMP (Shoreline management plan) -Hold the line -Advance the line -Retreat the line -Do nothing |
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What are the two main disadvantages of hard engineering managements? |
-Expensive -Ugly and look unnatural |
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Describe the benefits and costs of sea walls. |
-Reflects waves (and if recurved wave energy) -Can prevent beach access -Wave scours (waves attack foundations) -Unsightly -Can reflect wave energy back and create stronger waves -Can prevent coastal flooding |
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What are gabions? |
Cheap sea walls, they are weaker by a lot cheaper |
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Describe the benefits and costs of revetments. |
-break up incoming waves -can be destroyed in big storms -restrict beach -ugly |
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Describe the benefits and costs of rip rap. |
-easy to build -more expensive if built in sea -dissipate wave energy -look natural -allow build up of beach
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Describe the benefits and costs of groynes. |
-prevent longshore drift -larger beach dissipates wave energy and reduces erosion -may increase erosion downdrift -wood rots, high maintenance |
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Describe methods of soft engineering and their costs and benefits. |
Soft engineering is cheaper.
Planting vegetation -absorb rain and reduce sub aerial processes
Beach Replenishment -looks natural -beach for tourists -reduces wave energy -protects cliffs and land -erodes quickly and must be replaced every few years
Offshore breakwaters
Cliff Regrading -reduces steepness of cliff and so reducing mass movement -may have to destroy properties -still need cliff foot defences |
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Describe the difficulties in building defences. |
-Government think it is too expensive to protect farmland and isolated houses -Residents and business owners often disagree -Hard to persuade people that have lived their all their life that the protection of their property is not sustainable -Sea level predictions are unknown |
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Evaluate the opinions of different stakeholders towards coastal defences. |
Residents and business owners -favour hold the line -favour hard engineering as they want their coast protected -against ugly defences that will discourage tourists
Local Politicians and Council -Must be unbias when considering stakeholders -Want effective coastal protection at a low price
Local people living further inland -concerned local taxes will have to pay for defences -favour low cost options -do not want low value land protected
Environmentalists -do nothing -fear the destruction of habitats
Residents and businesses downdrift -worry that defences updrift will reduce their beach size and protection -favour defences that include everyone affected
Fishermen and boat users -need access to the sea |
