Flashcards
Coasts
Flashcards do conjunto (102)
- 1Describe the stages the literal zone can be divided into:Coast: land adjacent to the sea often heavily populated and urbanised
Backshore: above high tide level and only affected by waves during exceptionally high tides and storms
Foreshore: where wave processes occur between high and low tide marks
Nearshore: shallow waters near the land that are used extensively for fishing coastal trade and leisure
Offshore: the open sea - 2Describe the two categories coastal landscapes can be divided into:Rocky (cliffed)-coastlines with cliffs varying in height between a few meters to hundreds of meters
Coastal planes (with no cliffs) where the land gently slopes down towards the sea across an area od deposited sediment , often in the form of sand dunes or mud flats . - 3Describe the differences between primary and secondary coasts:Primary coasts: dominated by land based processes such as deposition at the coast from rivers or formation of new coastal land by lava flows.
Secondary coasts: dominated by marine erosion or deposition processes. - 4Describe the difference between emergent and submerging coastsEmergent: where the coast is rising relative to the sea level, for example, as a result of tectonic uplift.
Submergent: being flooded by the sea either because of sea level rise and/or subsiding land - 5State the different tidal ranges:Microtidal 0-2m
Mesotidal (2-4)
Macrotidal (4+m) - 6Describe the differences between high energy and low energy coasts:Low energy: sheltered coasts with limited fetch and low wind speeds resulting in small waves
High energy: exposed coasts facing prevailing winds with long wave fetches resulting in powerful waves. - 7Describe the different types of cliff profileMarine erosion dominated: wave action dominates, and cliffs tend to be steep, unvegetated and there is little rock debris at the foot of the cliff
Subaerial processes dominated: not actively eroded at the base by waves, shallower, curved slope and lower relief, surface run-off erosion and mass movement are responsible for the cliff shape. - 8Describe the characteristics of coastal planes and how they form:Low lying, low relief areas of land close to the coast, many contain estuary wetlands and marshes, being just above sea level and poorly drained because of the flatness of the landscape, coastal planes form when:
Sea level falls- exposing the sea bed of what was once a shallow continental shelf
Sediment brought from inland by rivers is deposited, causing coastal accretion and causing coasts to gradually move seawards
Sediment is moved from offshore stores (sand bars) and deposited along the coast by ocean currents - 9Describe Geological structure:Geological structure is the arrangement of rocks in three dimensions, there are three elements to this:
Strata: the different layers of rock in a cliff face
Faulting: major fractures that have moved rocks from their original positions
Deformation: tilting and folding by tectonic activity. - 10Describe the two different types of coast that geological structure can produce:Concordant coastlines: Rock strata runs parallel to a coastline
Discordant: Different rock strata intersect the coast at an angle. - 11What effects do headlands and bays have on wave crests?In open sea, waves crests are parallel, as waves approach a coast and move into shallower waters waves slow down and wave height increases, in bays, wave crests curve to fill the bay and wave height decreases, the straight wave crests refract, becoming curved, spreading out in bays and concentrating on the headlands the effect of wave refraction is to concentrate powerful waves at headlands to create lower, diverging wave crests, reducing erosion.
- 12Describe how bays are formed at concordant coasts with reference to a case study:At concordant coasts, rock strata run parallel to the coastline, the most well known example is Lulworth cove, the hard Portland limestone, and semi-hard Purbeck beds protect much safer rocks landward, marine erosion has broken through the resistant beds, and then rapidly eroded a wide cove behind. There is resistant chalk at the back of the cove, preventing further erosion inland.
At the Dalmatian coasts of the Adriatic sea is another example of a concordant coastline where, the geology is limestone, the limestone has been folded by tectonic activity into a series of anticlines and synclines, that trend parallel to the modern coastline. The underlying structure of upstanding anticlines and syncline troughs has been flooded by sea level rise to form a concordant coastline of long narrow islands arranged offshore. - 13What are anticlines and synclines?Anticlines and synclines are types of geological fold caused by tectonic compression. Anti-clines form crests and synclines cause troughs.
- 14What are the dominant characteristics that influence cliff profiles:Resistance of rock to erosion, dip in rock strata in relation to coastline.
- 15What is dip and what can it do?Dip, meaning the angle of strata in relation to horizontal, is itself a tectonic feature.
- 16Describe, with drawings, the different types of cliff profiles:Horizontal dip: Vertical or near-vertical profile with notches reflecting strata that are more easily eroded.
Seaward high angle: Sloping, low angle profile with one rock layer facing to the sea; vulnerable to rock slides down the dip slope.
Seaward dip low angle: Profile may exceed 90 degrees, highly vulnerable to rock fall
Landward dip: steep profiles producing a very stable cliff with reduced rock falls - 17What other geological features influence cliff erosion?Faults: either side of faults rocks are highly fractured and broken, vulnerable to erosion
Joints: occur at most rocks, often in regular patterns, dividing rock strata up into blocks with a regular shape.
Fissures: smaller cracks in rocks, still vulnerable to erosion.
Folded rock: often heavily fissured and jointed, making them vulnerable to erosion. - 18What are mircofeatures:Microfeatures are small scale coastal features such as caves and wave cut notches which form part of a cliff profile.
- 19What is coastal recession?Coastal recession is the rate at which a coast is moving inland
- 20Describe the three different rock types:Igneous- Basalt and granite- Very slow rate of erosion, less than 0.1cm a year, igneous rocks are crystalline, consisting of interlocking crystals, making them resistant erosion. Igneous rocks such as granite often have very few joints so limited weaknesses for erosion to exploit.
Metamorphic: slate- marble-slow rate of erosion, 0.1-0.3cm every year. Crystalline metamorphic rocks are resistant to erosion, many metamorphic rocks exhibit a feature called foliation- causes all the crystals to orientate in one direction- produces weaknesses. Metamorphic rocks are often folded and highly fractured, making them more vulnerable.
Sedimentary: sandstone- shale- moderate to fast rate of erosion, clastic and eroded faster, age of sedimentary rocks is important, geologically young rocks eroded fastest. - 21How is erosion and weathering resistance affected?How reactive minerals in the rock are to chemical weathering.
Whether the rocks are crystalline or clastic
The degree to which the rocks are fractured/jointed/fissured. - 22How can groundwater flow weaken rocks?Flow through layers of rock weakens rocks by removing the cement that binds sediment in the rocks together. It can also create high pore water pressure in the cliffs which affects their stability.
- 23What is unconsolidated material?Unconsolidated material is sediment that has not been cemented to form solid rock, a process known as lithification.
- 24How does vegetation stabilise coastal sediment?Vegetation stabilises coastal vegetation by: Roots of plants bind sediment together, making them harder to erode. When submerged plants provide a protective layer so the sediment surface is not directly exposed to moving water and erosion. Plants protect sediment from erosion by wind, reducing wind speed a the surface because of friction and vegetation.
- 25Describe the process of plant succession:Pioneer species will begin to grow in bare sand or mud. This is first stage, each subsequent stage is called a seral stage. The end result is called climatic, climax community.
- 26How does plant succession take place on sand dunes?Begins with the colonisation of embryo dunes by pioneer plant species. Embryo dune pioneer plants, stabilise the mobile sand by their root systems. Reduce wind speed by their root systems, reduce wind speed at the sand surface allowing more sand to be deposited. Add dead organic matter to the sand, beginning the process of soil formation.
- 27Why are estuarine areas ideal for the development of salt marshes?Sheltered from strong waves, so sediment can be deposited. River systems transport sediment to the river mouth which may be added to sediment flowing into the estuary at high tide.
- 28How do characteristic coastal landforms contribute to coastal landscapes?Wave types and erosional processes contribute by the production of new coastal landforms. Sediment deposition processes produce coastal landforms often colonised by plant succession, the sediment cell model shows coasts can operate as hostilic systems. Weathering and mass movement are important on some coastlines.
- 29How are waves formed?Waves are formed by friction between wind and water transferring energy from the wind to the water. The force of wind blowing on the surface of the water generates ripples which grow into waves when sustained. Waves are simply energy moving through water, the water itself moves up and down. There is some orbital water particle motion within the cave, but no net forward water particle production.
- 30What does wave size depend on?The strength of the wind, the duration the wind blows for, water depth, and wave fetch.
- 31What happens as waves approach the coast?At the water depth of approximately half the wavelength, the internal orbital motion of water within the wave touches the sea bed. This creates friction between the wave and the sea bed, and this slows down the wave. As the wave approaches the shore, wavelength decreases, and wave height increases so the waves bunch together. The wave crest begins to move forward much faster than the wave trough. Eventually the wave crest outruns the trough and the wave topples forward.
- 32Describe the characteristics of destructive and constructive waves:Constructive: Lave how wave height of less than one meter but long wavelength of up to 100m, are flat waves with a strong swash and weak backwash, have a strong swash that pushes sediment up the beach depositing it as a ridge of sediment at the top of the beach. Have backwash which drains into sediment.
Destructive waves: have a height over one meter and a wavelength of less than 20 meters. Have a strong backwash that erodes beach material and carries it offshore, creating an offshore ridge or berm. - 33How can beaches experience both destructive and constructive waves over different timescales.Over a day, as a storm passes, and the wind drops, destructive waves change to constructive waves
Between the summer and winter
Because of a change in climate, if climate change caused the UK to become stormier, destructive waves and winter beach profiles could become more common: - 34Describe how beach landforms change constantly:Storm beaches, high at the back of the beach, result from high energy deposition of very coarse sediment during the most severe storms.
Low channels and runnels between berms
Offshore ridges/bars formed by destructive wave erosion and subsequent deposition of sand and shingle offshore. - 35Describe some marine erosion processes:Hydraulic action- air trapped in cracks and fissures is compressed by the force of waves crashing against the cliff face. Pressure forces these cracks open, meaning more air is trapped and greater force is experienced in the next cycle of compression. This process dislodges blocks of rock from the surface of the cliff.
Abrasion (corrasion)- Sediment is picked up by breaking waves and tossed against the cliff face, gradually chiselling away at the surface and wearing it down.
Attrition: As sediment is moved around by the waves the numerous collisions between particles slowly chip fragments off the sediment, making it smaller and more rounded over time.
Corrosion: Carbonate rocks (limestones) are vulnerable to solution by rainwater, spray and seawater. - 36Describe how a wave cut notch is formed:A wave cut notch is eroded at the base of a cliff by the process of abrasion and hydraulic action. As the notch becomes deeper, the overhanging rock above It becomes unstable and eventually collapses in a rock fall. Repeated cycles of notch cutting and collapse cause cliffs to recede inland. The former cliff position is shown by a horizontal rock platform visible at low tide, called a wave cut platform.
- 37Describe the different transportational processes:Traction- sediment rolls along pushed by currents and waves
Saltation- Sediment bounces along either because of the force of the water or of wind
Suspension- Sediment is carried in the water column.
Solution- Dissolved material is carried in the water as a solution. - 38Describe the process of longshore drift:Longshore drift is the process of transporting sediment along a coastline. It occurs when wave crests approach a coast at an angle- rather than 90 degrees. As a result, the swash from the breaking waves and the subsequent backwash follow different angles up and down the beach in a zig zag pattern. On most coastlines, there is a dominant prevailing wind so over time, there is a dominant direction of longshore drift.
- 39Describe the two ways sediment deposition can occur:1. Gravity settling occurs when the energy of transporting water becomes too low to move sediment. Large sediment will be deposited first, then smaller sediment.
2. Flocculation is a depostional process that is important for very small particles, such as clay, which are so small they remain suspended in water. clay particles clump together through electrical or chemical attraction, and become large enough to sink. - 40Summarise the formation of a spit:Spit: Sand/shingle ridge extending beyond a turn in a coastline, usually greater than 30 degrees, at the turn, the longshore drift current spreads out and loses energy, this causes deposition. The length of the spit is reliant on secondary currents causing erosion, either the flow of a river or wave action.
- 41Summarise the formation of a bayhead beach:Waves break at 90 degrees to the shoreline and move sediment into a bay where a beach forms. Through wave refraction, erosion is concentrated at headlands and the bay is an area of depostion
- 42Summarise the formation of a tombolo:A sand or shingle bar that links a coastline to an offshore island. Tombolos are formed as a result of wave refraction around an offshore island which creates an area of calm water and depostion between the island and the coast. Opposing longshore currents may play a role, in which case the depositional feature is similar to a spit.
- 43Summarise the formation of a barrier/bar:A sand or shingle beach connecting two areas of land, with a shallow water lagoon behind. This forms when a spit extends across a bay, closing it off.
- 44Summarise the formation on a hooked/recurved spit:A spit whose end is curved landward, into a bay or inlet. The seaward (distal) end of the spit naturally curves landward into the shallower water and the "hook" may be made more pronounced by waves from a secondary direction to the prevailing wind.
- 45Summarise the formation of a cuspate forelandroughly triangular shaped features extending out from a shoreline. There is some debate about their formation, but one hypothesis suggests they result from the growth of two spits from opposing longshore drift directions
- 46What are the three components of sediment systems?Sources: places where sediment is generated, such as cliffs or eroding sand dunes. some sources are offshore bars and river systems and these are an important source of sediment for the coast.
Transfer zone: places where sediment is moving alongshore through longshore drift and offshore currents. Beaches and parts of dunes and salt marshes perform this function
sinks: locations where the dominant process is deposition and where depostitional landforms are created. - 47How do sediment cell systems work?Sediment cell systems consist of inputs, transfers and outputs. Under natural conditions they operate under a state of dynamic equilibrium, for short periods this equilibrium may be broken but it will tend to return to balance over time. Negative feedback mechanisms help to maintain this balance.
- 48What is weathering?Weathering is a subaerial process. There are three main types:
1. Mechanical- the breakdown of rocks by the exertion of physical force and does not involve any chemical change
2. chemical weathering involves a chemical reaction and the generation of new chemical compounds
3.Biological weathering- often speeds up mechanical and chemical weathering through the action of plants, bacteria or animals. - 49Describe some examples of mechanical weathering:freeze thaw- Water expands in volume when it freezes, exerting a force within cracks and fissures; repeated cycles force cracks open and loosen rocks. any rocks with exposed cracks/fissures are vulnerable.
Salt crystallisation- The growth of salt crystals in cracks and pore spaces can exert a breaking force although, less than for freeze thaw. - 50Describe some examples of chemical weathering:Carbonation: The slow dissolution of limestone due to rainfall (weak carbonic acid) producing calcium bicarbonate in solution.
Hydrolysis: The breakdown of minerals to form new clay minerals plus materials in solution due to the effect of water and dissolved carbon dioxide. igneous and metamorphic rocks containing silicate minerals are especially vulnerable.
Oxidation: The addition of oxygen to minerals, especially iron compounds which produces iron oxides and increases volume contributing to mechanical breakdown. sandstones, siltstones and shale which contain iron are especially vulnerable. - 51Explain some examples of Biological weatheringPlant roots: trees and plant roots growing in cracks and fissures forcing rocks apart. An important process on vegetated cliff tops which can contribute to rock fall.
Rock boring: There are many species of clams and molluscs that bore into the rock and may secrete chemicals that dissolve the rocks. sedimentary rocks, especially carbonate rocks located at the intertidal zone are at particular risk. - 52Define Mass movement:Mass movement refers to the downslope movement of rock and soil. It is an umbrella term for a range of specific movements such as landslide rockfall and rotational slide. It is another subaerial process.
- 53Describe some mass movement processes:Fall: Rockfalls or blockfalls are a rapid form of mass movement. On coasts blocks of rocks can be dislodged by mechanical weathering or by hydraulic action or erosion. Undercutting by cliffs by the creation of wave cut notches can lead to large falls.
Topple: Geological structure influences topples . Where rock strata have a very steep seaward dip, undercutting by erosion will quickly lead to instability and blocks of material toppling seaward.
Rotational slumping: Mass movements can occur along a curved failure surface. In the case of a rotational slide, huge masses of material can slowly rotate downslope over periods lasting from days to years. Water plays an important role in rotational slides. Rotational slides create a back scar and terraced cliff profile.
Flow: Flows are common in weak rocks such as clay or unconsolidated sands. These materials can become saturated, lose their cohesion and flow downslope , heavy rainfall combined with high waves and tides can contribute to saturation. - 54Describe the two types of sea level change:Eustatic change: A rise or fall in sea level.
Isostatic change: Local rise or fall in land level - 55Describe how Eustatic rise and fall happensEustatic fall: During glacial periods, when ice sheets form on land in high altitudes, water evaporated from the sea is locked up on the land as ice, leading to a global fall in sea level.
Eustatic Rise: At the end of a glacial period, melting ice sheets return water to the sea and sea level rises globally. Global temperature increases cause the volume of ocean water to increase due to thermal expansion, leading to sea level rise. - 56Describe how isostatic rise and fall happens:Isostatic fall: during the build up of land-based ice sheets, the colossal weight of ice causes the earth's crust to sage. When ice sheets melt, the land surface slowly rebounds upwards.
Isostatic rise: Land can sink at the coast because of depostition of sediment, especially in large river deltas where the weight of sediment distribution leads to very slow crustal sag and delta subsidence. - 57Describe sea level change in the UKSince the end of the last ice age 12,000 years ago, the UK has felt the impact of continuing sea level change. Scotland is still rebounding upwards because of post-glacial adjustment, England and wales on the other hand are subsiding up to 1mm a year. The UK is pivoting, with the south sinking and the north rising. sea level rise caused by global warming compounds the effect in the south, but slows the effect in the north.
- 58What are emergent coastlines?Coastline with landforms that reflect previous sea levels caused by eustatic and isostatic change.
- 59What are submergent coastlines?Submergent coasts are coastlines that were never affected by glacial ice cover and do not experience post-glacial adjustment. Instead they were drowned when post-glacial sea levels rose.
- 60Describe the formation and characteristics of a fjordFjords are submergent landfrorms found on the coastlines of Norway and Canada. Fjords are drowned valleys, but they differ from rias in that the drowned valley is a U-shaped glacial valley, the fjord is often deeper than the adjacent sea, some over 1000m deep, at the seaward end of the fjord, there is a submerged lip, representing the former extent of the glacier that filled the valley.
- 61Describe the formation and characteristics of barrier island landformsFound on the east coast of the USA, they may have formed as lines of coastal sand dunes attached to the shore, later sea level rise flooded the land behind the dunes forming a lagoon, but the dunes themselves were not eroded so became islands, as sea levels continued to rise, the dune systems slowly migrated landwards.
- 62What are the factors that cause sea level rise?Thermal expansion: of the oceans- depends on how much global temperatures climb.
Melting of mountain glaciers in the alps, Himalayas and other mountain ranges will increase ocean water volume.
Melting of major ice sheets, could drastically increase global sea level. - 63What are the characteristics of rapidly retreating coastlines?Long wave fetch, large destructive ocean waves, soft geology, cliffs with structural weaknesses such as seaward rock dip and faults, cliffs that are vulnerable to mass movement and weathering , as well as marine erosion, strong long shore drift, so eroded debris is quickly removed exposing the cliff base.
- 64Using case studies, describe how the construction of dams can worsen coastal erosion:The construction of major dams on rivers can trap sediment behind the dam wall. This then starves the coast of a sediment source, leading to significant consequences.
The construction of the Aswan High Dam on the river Nile in 1964 reduced sediment volume from 130 million tonnes a year to 15 million tonnes a year. Erosion rates jumped from 25m a year to 200m a year. The construction of the Akosombo dam in Ghana in 1965 reduced flow of sediment down the river volta from 70 million cubic meters per year to less than 7 million, with major impacts on longshore drift and coastal erosion. - 65What is Dredging and why is it a problem?Dredging is the movement of sediment from the seabed or river bed. It is often done to make concrete foundations or to make navigation channels deeper. The removal of sediment from it's source can cause increased erosion.
- 66Use case studies to describe how erosion rate can varyOn the Holderness coast in East Yorkshire average annual erosion is around 1.25m a year, but there were wide variations from 0-6m a year, this is because coastal defences at Hornsea, Mapleton and Withernsea have stopped erosion, these defences have starved places further south of sediment as groynes have interrupted longshore drift, erosion rate therefore generally increases from north to south, some areas of boulder clay are more vulnerable to erosion rates than others, some cliffs are more susceptible to mass movement.
- 67Why is low lying coastal land often densely populated?Coastlines are popular with tourists, especially when access to beaches and sea is easy. Deltas and estuaries are ideal locations for trade between up river places and places along the coast and across the sea. Deltas and coastal plains are especially fertile and ideal for farming.
- 68Explain, with reference to case studies, the problems of coastal flooding at river deltas:Shanghai- located on the Yangtze river delta, with a population of 24 million, Karachi- located on the Indus river delta with a population of 23.5 million.
Sediment trapped upstream by dams, reduces new deposition of delta surface
Storm surges from cyclones flood the delta more frequently
River straightening for navigation means faster river flow and sediment being propelled offshore
Destruction of mangrove forests for wood and charcoal exposes the coast to erosion
Delta subsidence is caused by weight of sediment deposition, which is balanced by the new deposition on the delta surface - 69How is a storm surge caused?The most common cause of coastal flooding is storm surges events caused by a depression (low pressure weather system) in the mid latitudes, a tropical cyclone in areas just north and south of the equator. Strong winds from these weather systems push waves onshore, increasing the effective height of the sea, if high tides occur at the same time as a storm surge and offshore winds, the sea levels can rise even more. Coastal topography can also have an effect, In bays, the storm surge can be funnelled into increasingly narrow spaces between coastlines.
- 70Give a case study for storm surges:North Sea Storm surge, December 2013 - caused by a depression named xaver. It had major impacts due to 80mph winds and a storm surge approaching 6m
Significant coastal flooding in boston, hull, skegness and whitby
Scotland's rail network was shut down and 100 homes lost power
About 2500 coastal homes and businesses in the Uk were flooded
Across the countries affect, 15 died, forecasting, warning and evacuation limited scale of damage - 71Why is bangladesh particularly vulnerable to storm surgesMuch of the country is a low lying river delta, only 1-3m above sea level
incoming storm surges meet outgoing river discharges from the ganges river, meaning river flooding and coastal flooding combine
much of the coastline consists of unconsolidated delta sediment, which is very susceptible to erosion.
deforestation of mangrove forests has removed vegetation that once stabilised coastal swamps and dissipated wave energy during cyclones
The triangular shape of the bay of bengal concentrates cyclone storm surge as it moves north, increasing it's wave height
Three Storm surges have hit bangladesh since 1970, death tolls have fallen over time due to improved warnings, the construction of cyclone shelters and better aid response. 1970 cyclone had a 10m wave height and killed 400,000, and cost $90 million
2007 cyclone, killed 15,000, but cost $1.7 billion - 72What are the coastal risks posed by global warming?Sea level- sea level will rise by between 28-98cm by 2100- 55cm on average
Delta flooding- The area of the worlds major deltas at risk from flooding is likely to increase to 50%
Tropical cyclones- The frequency of tropical cyclones is likely to remain unchanged, but there could be more of the largest storms
Storm surges- Storm surges linked to depressions are likely to become more common
Wind and waves-There is some evidence of increased wind speeds and large waves
Coastal erosion- Erosion will generally increase because of the combined effects of changes to weather systems and sea level. - 73Describe some economic, social and environmental costs of coastal recession:Economic: Loss of property in the form of homes, businesses and farmland. These are relatively easy to quantify.
Social Costs: Costs of relocation and loss of livelihood/jobs (which can be quantified) but also include impact on health (such as stress and worry) which are harder to quantify
Environmental costs: Loss of coastal ecosystems and habitats. These are impossible to quantify financially but are likely to be small. - 74Why are economic losses to erosion small:Erosion happens slowly with a small number of properties affected over a long period of time,
property that is at risk loses it's value long before it is destroyed by erosion, because potential buyers recognise the risk
areas of high density population, especially towns and villages tend to be protected by coastal defences - 75What problems does coastal recession pose for coastal communities?Falling property values as date of eventual loss approaches, an inability to sell their property because the possibility of loss by erosion is too great, an inability to insure against loss,
the loss of their major asset, and facing the costs of getting a new home,
an increasingly unattractive environment scarred by collapsing cliffs, failing sea defences and blocked roads and paths - 76What help is there for those affected by coastal recession in the UK?In the UK, help consists of "Coastal Pathfinders Scheme" - cover the cost of property demolition and site restoration, provide up to £1000 in relocation expenses such as removal vans and storage, provide up to £200 in hardship expenses, have rollback policies, giving people fast-tracked planning approval to build a new home somewhere.
- 77Give some case studies for the impacts of coastal flooding on communities:Netherlands 1953 (North Sea Flood) Mid latitude depression moving south through the north sea generating a 5m storm surge, almost 10% of dutch farmland was flooded, 40,000 buildings damaged and 10,000 destroyed, 1800 dead
UK 2013-2014 Winter Storms: Coastal and other flooding caused by a succession of depressions and other storm surges, damage of around £1 billion, over the coarse of the winter
USA 2012 Hurricane: Landfall of hurricane sandy in New Jersey and other US states, with a 4m storm surge, US $70billion in damage, 6 million people lost power and 350,000 homes in New Jersey were damaged or destroyed . 6300 dead - 78Using case studies, explain how coastal erosion can create environmental refugees:By 2100, some places sea level rise resulting from global warming will be difficult to manage, the most at risk places being the maldives ,Tuvalu and Barbados. Coral reefs which act as a natural defence against erosion, are being destroyed by global warming induced coral bleaching, water supply is limited and at risk from salt water incursion as sea level rises and groundwater is overused. They have narrow economies based on tourism and fishing which are easily disrupted. They have high population densities and very limited space, so relocation is non-existant
- 79What is hard engineering, with references to it's advantages and disadvantages:Hard engineering aims to directly stop physical erosion processes altogether or to alter them to protect the coast. The advantages of hard engineering are that it is obvious to at-risk people that something is being done, and if implemented correctly, can protect an area of cost for decades. The disadvantages are that costs are very high, and there are ongoing maintenance costs, even very carefully designed engineering solutions are prone to failure, coastlines are made visually unattractive and the needs of coastal ecosystems are overlooked.
- 80Describe some methods of hard engineering:Rip Rap (rock armour) - Large igneous or metamorphic rocks are distributed at either the base of a cliff or a sea wall to break up and dissipate wave energy. These reduce the wave energy but can also lead to sediment deposition between rocks.
Offshore rock breakwater: Large igneous or metamorphic rocks distributed offshore to create a calm lagoon behind, breakwaters force waves to break offshore, rather than at the coast, reducing wave energy and erosive force. This encourages deposition between the breakwater and the beach, but can interfere with longshore drift
Sea wall: concrete wall with steel reinforcement and deep piled foundations, acts as a physical barrier against erosion, also act as flood barriers, modern sea walls are designed to dissipate, not reflect wave energy, can lead to destruction of natural cliff face and foreshore environment.
Revetments: Stone, timber or interlocking concrete sloping structures that are permeable. They absorb wave energy and reduce swash distance by encouraging infiltration. Reduced wave power can encourage deposition and may become vegetated. - 81Describe groynes:Vertical stone or timber fences built at 90 degrees to the coast, spaced along the beach. They prevent longshore movement of sediment, and encourage deposition building a wider, higher beach, however they prevent longhsore drift, creating sediment starvation and increased erosion downdrift.
- 82Describe soft engineering with reference to its advantages and disadvantages:Soft engineering is an alternative to hard engineering that attempts to work with natural systems and processes to reduce coastal erosion and flood threat. Soft engineering is usually less obvious and intrusive at the coast, but is not suitable for all coasts.
- 83Describe some methods of soft engineering, with references to their advantages and disadvantages:Beach Nourishment: Artificial replenishment of beach sediment to replace sediment lost by erosion, to enlarge the beach so that it dissipates wave energy and reduces wave erosion. Costs of £2million for every sqkm of beach, sediment must also be sourced from elsewhere in the local sediment cell.
Cliff regrading and drainage: Cliff slope angles reduced to increase stability and re-vegetated to reduce surface erosion. Costs of £1 million per 100m, can be disruptive during construction.
Dune stabilisation: Fences are used to reduce wind speeds across the dunes, which are then replanted with the marram and lyme grass to stabilise the surface. Dune fencing costs £400-£2000 per 100m and replanting the dues about £1000 per 100m. - 84Define the term sustainable coastal management:Managing the wider coastal zone in terms of people and their economic livelihood, social and cultural well-being, safety from coastal hazards, as well as minimising the environmental and ecological impacts.
- 85Describe what sustainable coastal management may include:Monitoring coastal change, and adapting to unexpected trends, Managing natural resources to ensure long-term productivity, managing flood and erosion risk, where possible, relocating to safe areas, creating alternative livelihoods before existing ones are lost to the sea, adapting to sea level rise by relocating, alternative building methods and water supplies.
Educating communities to understand why change is needed and how to adapt. - 86Why may adopting coastal management cause conflict?Coastal natural resources may have to be used less in order to protect them - some people may lose income.
relocation may be needed where engineering solutions are too costly or not technically feasible
some erosion and or flooding will always occur, as engineering schemes cannot protect against all threats
future trends, such as sea level rise, may change, creating uncertainty and the need to change plan. - 87What is is integrated Coastal zone management?IICZM is coastal management planning over the long term, involving all stakeholders, working with natural processes and using adaptive management.
- 88What are the key features of ICZM?The entire coastal zone is managed, not just the narrow zone where breaking waves and erosion cause flooding. This includes ecosystems, resources and human activity in the zone. It recognises the importance of the coastal zone to people's livelihoods, as globally, very large numbers of people work and live at the coast, but their activities tend to degrade the environment. It recognises the management of the coast must be sustainable, meaning that economic development has to take place to improve the quality of life of people but that this needs to be environmentally appropriate and equtable
- 89How does ICZM work?ICZM works with the concept of littoral cells or sediment cells. The coastline is divided into littoral cells and each managed as an integrated unit, in enland and wales there are 11 cells, each cell is managed either as a whole unit or sub unit, in both cases a plan called a shoreline management plan is used, the shoreline management plan area is further divided into sub-cells, smps extend across council, so many councils must work together on an agreed smp to manage an extended stretch of coastline.
- 90Explain different coastal management strategies:In the UK, coastal management is overseen by DEFRA.
No active intervention- No investment in defending against flooding or erosion, whether or not coastal defences have existed previously. The coast is allowed to erode landward/or flood.
Strategic realignment: Allow the coastline to move naturally (in most cases recede) but managing the process to direct it in certain areas, sometimes called strategic realignment or strategic retreat.
Hold the line: Build or maintain coastal defences so that the position of the shoreline remains the same over time
Advance the line: Build new coastal defences on the seaward side of the existing coastline. Usually involving land reclamation - 91What are decisions about what policy of coastal management made in consideration of?The economic value of the assets that could be protected, the technical feasibility of engineering solutions, some solutions may not be possible, the cultural and ecological value of the land, pressure from communities, the social value of communities that have existed for centuries
- 92What is a cost benefit analysis?Cost benefit analysis is used to help to decide if defending a coastline from erosion or flooding is economically viable.
- 93What is an environmental impact assessment?Coastal management usually requires and environmental impact assessment to be carried out, this is separate from the cost benefit analysis, but it may inform the final CBA. It aims to identify, the short term impacts of construction on a coastal environment, the long term impacts of building new sea defences or changing a policy from hold the line to no active intervention or managed realignment. EIA is wide ranging and includes assessments of, impacts of water movement and sediment flow, impacts on water quality, possible changes to fauna and flora, wider environmental impacts such as air quality and noise pollution, mainly during construction.
- 94Describe, how coastal management can lead to both winners and losersCoastal managers produce plans for entire SMP areas, so some areas are protected, while others are not.
Local councils and governments have limited resources, so some areas are protected while others are not. - 95Give an example where all stakeholders could agree on a course of action for coastal management:The blackwater estuary in essex is an area of tidal salt marsh and low lying farmland. Prone to flooding and coastal erosion, farmland was once protected by flood embankments and revetments. Over the last 30 years it has become clear that responding to sea levels and greater erosion by building higher coastal defences in places like blackwater is not sustainable.
The solution adopted was radical. In 2000 Essex wildlife trust purchased abbots farm on the black water estuary, which was threatened by erosion and flooding. A 4000 acre realignment programme was created by making five breaches in a sea wall in 2002, allowing a new salt marsh to form inland. The abbots hall farm owners received the market price for their farm, the very high costs of hold the line policy were avoided, but flood risk was reduced. New paths and river ways were created for leisure activities. Additional tourism streams from ecotourism and wildlife were created. - 96Why is coastal erosion rapid in some areas of the developing world?Upstream dams are reducing supply to the coast and disrupting local sediment cells
Rapid, unplanned coastal development, urbanisation and the development of tourist resorts with piecemeal defences and no overall plan. Widespread destruction of mangrove forests for fuel wood and shrimp ponds expose sediments prone to rapid erosion. - 97Describe the process of sediment cells:Along a coastline, erosion, transport and deposition processes operate in a literal system. A sediment cell has sources, transfers and sinks. Each cell can be regarded as a closed system, when there are large barriers between them, with few transfers between them. Under certain conditions. Transfers will take place, erosion from one and deposition in another. Longshore drift and currents transfer sediment within a cell. The coastline of England and wales is divided into 11 cells.
- 98How are raised beaches and Fossil cliffs formed?Raised Beach: A raised beach is a former beach now above high tide, some raised beaches consist of several levels, each indicating a different stage of uplift. Features such as rounded pebbles and boulders are present, but smaller particles are usually removed, influenced by isostatic rebound.
Fossil Cliffs: A fossil cliff is a near vertical slope initially formed by marine processes, but now some distance inland. - 99How are Rias formed:A ria is a flooded river valley, during ice ages some land areas are not covered with Ice but had frozen ground, so rivers carved valleys with some steeper sides than normal. Sea levels rose again after the ice melted and drowned the mouth of the valleys.
- 100Describe Bangladesh as a case study:Bangladesh is the country most at risk from sea level rise (between 6 and 22mm a year) and from storm surges linked to tropical cyclones, 40% of all recorded storm surges have taken place in Bangladesh. In 1970, a storm surge killed 500,000. Storm surges have caused 1.3 million deaths since 1700. In the past, they have reached 100km inland and further sea level could mean this could soon become much worse, a 1.5m sea level rise could flood 22,000km, displacing 16 million people.
- 101Give Kiribati as an example for environmental refugees:Situated in the middle of the pacific ocean, Kiribati is composed of 33 small islands, most of the population live in tarawa, where the maximum height of the land is 3m above sea level, sea level rise from storm surges due to climate change has increased flooding and erosion and contamination of freshwater supplies. The Kiribati government has looked at buying 23km2 of Fiji's vanua levi island, ready to relocate it's population.
- 102Describe Happisburgh as a case study for policy conflict:Happisburgh has repeatedly failed to qualify for government grants for coastal defences, a soft engineering method has been applied to the dismay of locals, and the residents of Beach road, who have gradually lost their homes to the sea, by 2100, the shoreline may recede by 200m, with a loss of 50 homes and a caravan site. In 2003 the lifeboat and beach ramp were lost, prompting concerns that tourism could be affected. In 1996, managed retreat, this did not change in 2004, just renamed to no active intervention. House values are low and people cannot afford to move elsewhere, no compensation available. Campaigning by the CCAC raised awareness of the coastal erosion issue, not only locally but troughout the UK.
Informações
- Descrição
- A level Geography FlashCards sobre Coasts, criado por toby blewett em 09-03-2018.
- Criado por
- toby blewett
- Visualizações
- 4
- Avaliação