Flashcards in Coasts Deck (177):
What is input?
Material or energy moving into the system from the outisde
What is output?
Material or energy moving from the system to the outside
What is energy?
Power or driving force
What are stores/ components?
The individual elements or part of a system
What are flows/transfers?
The link or relationships between the components
What is positive feedback?
Where a flow/transfer leads to increase or growth
What is negative feedback?
Where a flow/transfer leads to decrease or decline
What is dynamic equilibrium?
This represents a state of balance within a constantly changing system
Give an example of input
Give an example of an output
Ocean currents, rip tides, sediment transfer, evaporation
Give an example of energy
Energy associated with flowing water, the effects of gravity on cliffs and moving air
Give an example of stores/components
Beach,sand dunes, nearshore sediment
Give an example of flows/transfers
Wind-blown sand, mass movement processes, long shore drift
Give an example of positive feedback
Coastal management can lead to an increase in erosion somewhere along the coast. Groynes trap sediment, depriving areas further down- drift of beach replenishment and this can exacerbate erosion.
Give an example of negative feedback
When the rate of weathering and mass movement exceeds the rate of cliff-foot erosion and a scree slope is formed. Over time this apron of material extends up the cliff face protecting the cliff face from sub aerial processes. Leading to a reduction in the effectiveness of weathering and mass movement.
Give an example of dynamic equilibrium
Constructive waves build up a beach making it steeper. This encourages the formation of destructive waves that plunge rather than surge. Redistribution of sediment offshore by destructive waves reduces the beach gradient which in turn encourages the waves to become more destructive. This is a state of constant dynamic equilibrium between the type of wave and the angle of the beach.
What factors affect wave energy?
-The strength of the wind (determined by the pressure gradient)
-The duration of the wind (the longer the wind blows, the more powerful waves will become)
-The fetch (the distance of open water over which the wind blows. The longer the fetch, the more powerful the waves)
How are waves formed?
As air moves across the water, frictional drag disturbs the surface and forms ripples or waves. In the open sea there is little horizontal movement of water. Instead there is an orbital motion of the water particles. Close to the coast, horizontal movement of water does occur as waves are driven onshore to break of the beach
Compare destructive and constructive waves
-Distant weather systems generage these waves in the open ocean
-Low surging waves with a long wavelength
-Strong swash, weak backwash
-Associated with a gentle beach profile
-Local storms are responsible for these waves
-High, plunging waves, with a short wavelength
-Usually associated with a steeper beach profile
What are tides?
Changes in the water level of seas and oceans caused by the gravitational pull of the moon and a to a lesser extent, the sun.
What is tidal range?
The coastline experiences two high and two low tides in. The relative difference in height between these tides is tidal range.
What are rip currents?
Strong localised underwater currents that occur in some beaches, posing a considerable danger to swimmers and surfers. They are commonly formed when a series of plunging waves cause a temporary build up of water at the top of a beach. Met with resistance from the breaking waves, water returning down the beach (the backwash) is forced down below the surface following troughs and small undulations in the beach profile.
Where are rocky coasts generally found?
-in the UK where do these tend to be?
In high energy environments
-stretches of the Atlantic-facing coast e.g Cornwall
-where the rate of erosion exceeds the rate of depositon
Give 3 examples of erosional landforms that are found in high energy environments
-wave cut platforms
What is indicative of a low energy coast?
-in the Uk where do these tend to be?
Sandy and estuarine coasts
-stretches of the coast where the waves are less powerful, or where the waves are sheltered from large waves (e.g bays of Lincolnshire)
-where the rate of deposition exceeds the rate of erosion
Give 3 examples of erosional landforms that are found in low energy environments
What does wave refraction cause?
Energy to be concentrated on headlands and dissipated at bays
What erosive features may wave refraction cause?
-depositional features- beaches
How can negative feedback be seen in wave refraction?
Variations in rock strength lead to the formation of headlands and bays
This causes wave refraction which in turn encourages erosion of the headlands and deposition in the bays-working against the erosion of the softer rock that formed the bay originally
-if conditions remained stable for a long period of time a state of equilibrium would be reached where the shape of the coastline remains static due to a balance between the potential erodibility of the rocks and the effect of wave refraction.
Give 6 sources of sediment
-rivers (this will be deposited in river mouths and estuaries where it will be reworked by waves, tides and currents)
-longshore drift (sediment is transported from one stretch of coastline (as an output) to another stretch of coastline (as an input)
-wind (wind-blown sand can be deposited in coastal regions). Sand dunes are semi-dynamic features at the coast that represent both accumulations (sinks) of sand and potential sources
-glaciers (in Alaska ice shelves carve depositing sediment trapped within the ice )
-offshore (storm surges can be responsible for input of sediment into the coastal system)
What is a sediment cell?
A stretch of coastline, usually bordered by two prominent headlands, where the movement of sediment is more or less contained
What are the inputs of a sediment cell?
These are derived from the river, coastal erosion and offshore sources such as banks or bars
What are the the transfers of a sediment cell?
These involve longshore (littoral) drift together with onshore and offshore processes such as rip currents
What are the stores of sediment cells?
These include the beach, sand dunes and offshore deposits (bands and bars)
What would you consider a state of dynamic equilibrium?
-how could this balance be upset?
Where erosion and deposition are balanced?
-a surge in river discharge following floods introducing vast amount of sediment into the system
-an extreme storm may erode transport and transfer sediment out of the system
What is weathering?
The breakdown or disintegration of rock in situ
What is mechanical (physical )weathering?
The breakup of rocks without any chemical changes taking place
What are the different types of mechanical (physical weathering)?
-Freeze thaw weathering (chalk is the main rock affected)
-Salt crystallisation (when salt water evaporates, it leaves salt crystals behind. These can grow over time and exert stresses in the rocks. Salt can also corrode rock, particularly if it contains traces of iron
-wetting and drying (rocks such as clay expand when they get wet and contract as they dry. This can cause then to crack and break up)
What is biological weathering?
The breakdown of rocks by organic activity.
How can biological weathering take place on the coast?
-thin plants roots grow into small cracks in a cliff face. These cracks widen as the roots grow which breaks up the rock
-water running through decaying vegetation becomes acidic, which leads to increased chemical weathering
-birds (e.g puffins and sand martins and animals (rabbits) dig burrows into cliffs
-marine organisms are also capable of burrowing into rocks (piddocks) or of secreting aids (e.g limpets)
What is chemical weathering?
Involves a chemical reaction where salts may be dissolved or a clay-like deposit may result which is then easily eroded.
What are the three types of chemical weathering?
-Carbonation (rainwater absorbs carbon dioxide from the air to form a weak carbonic acid. The reacts with calcium carbonate in rocks, such as limestone and chalk, to form calcium bicarbonate which is easily dissolved. The cooler the temperature of the rainwater the more carbon dioxide is absorbed. So carbonation is more effective in winter
-Oxidation (the reaction of rock minerals with oxygen e.g iron forms a rusty red power
-Solution (the dissolving of rock minerals such as rock mi eras, such as halite (rock salt)
What is mass movement?
The downhill movement of material under the influence of gravity
Give an example of mass movement
Feb 2014- the Jurassic coast near Lyme regis in Dorset was affected by a number of dramatic landslips, damaging holiday chalets. The exposed stretch of the coastline is constantly being reshaped.
What are the four main types of mass movement?
What is soil creep?
-an extremely slow form of movement of individual soil particles downhill
-often involves particles rising towards the ground surface due to wetting or freezing and then returning veritically to the surface in response to gravity as the soil dries out or thaws. This zig zag movement is similar to the of longshore drift
What is landslide
-a block of rock moving very rapidly downhill along a planar surface, often a bedding plane that is roughly parallel to the ground surface. Unlike a mudflow where the moving material becomes mixed, the moving block of material in landslide remains largely intact
-frequently triggered by earthquakes or very heavy rainfall when the slip surface becomes lubricated and friction is reduced.
-tend to be a considerable threat to people and property.
What is a mudflow?
A mudflow involves earth and mud flowing downhill, usually over unconsolidated or weak bedrock such as clay, often after heavy rainfall. Water gets trapped within the rock, increasing pore water pressure, which forces rock particles apart and leads to slope failure. Pore water pressure is a form of energy within the slope system and is an extremely important factor in determining slope instability. Mudflows are often sudden and fast flowing
What is rockfall?
A rockfall involves the sudden collapse or breaking away of individual rock fragments at a cliff face. Often triggered by mechanical weathering or an earthquake. Once broken away from the source the rocks fall or bounce down the slope to form scree at the foot of a slope. Scree often forms a temporary store within the coastal system, with material gradually being moved and transported elsewhere by the store. The scree forms an impute to the sediment cell
What is runoff?
When overland flow occurs down a slope or cliff face, small particles are moved downslope to enter the littoral zone, potentially forming an input to the sediment cell. Runoff transfers both water and sediment. Toxic chemicals can contaminate storm water and cause threats to coastal ecosystems
What is solifluction?
Specific to cold periglacial environments
In the summer the surface layer of soil thaws out and becomes extremely saturated because it lies on top of impermeable frozen ground. Known as the active layer, this sodden soil with its blanket of vegetation slowly moves downhill by a combination of heave and flow. Solifluction characteristically formed features called solifluction lobes.
What is landslip of slump?
-Its slide surface is curved rather than flat
-commonly occur in weak and unconsolidated clays and sands often when permeable rock overlies impermeable rock which causes a build up of poe water pressure.
Describe hydraulic action
When a wave advances air can be trapped and compressed. When the wave retreats the compressed air expands. This continuous process can weaken joints and cracks in the cliff, causing pieces of rock to break off. Simultaneously, bubbles formed in the water may implode under high pressure. This generates tiny jets of water which will over time will erode the rock. This process is specifically termed cavitation.
Describe wave quarrying
The action of waves breaking against unconsolidated material such as sands and gravels. Waves scoop out the loose material in a similar way to the action of a giant digger in the quarry on land
When waves advance they pick up sand and pebbles from the seabed, a temporary store. When they break at the base of a cliff, the transported material is hurled at the base of a cliff, the transported material is hurled at the cliff foot-chipping away at the rock.
Describe solution (corrosion)
Weak acids in seawater can dissolve alkaline rock (e.g chalk) or the alkaline cement that bonds rock particles together. This is solution
What is attrition?
The gradual wearing down of rock particles by impact and abrasion, as the pieces of rock are moved by waves, tides and currents. This process gradually makes stones rounder and smoother.
What are the two factors affecting coastal erosion?
most erosion happens during winter storms (e.g dawlish in 2014 when destructive waves are at their largest)
-rock type (lithology)
physical strength and chemistry. Tough and resistant rocks such as granite erode at slower rates compared to weaker clays and shales.
e.g cracks joints
-Presence of absence of a beach
beaches absorb wave energy and reduce the impact of waves on a cliff
weathering and mass movement will weaken cliffs
What is traction?
The rolling of coarse sediment along the saa bed that is too heavy to be picked up and carried by the sea
What is saltation?
Sediment 'bounced' along the seabed, light enough to be picked up or dislodged but too heavy to remain within the flow of the water
What is suspension?
Smaller, lighter sediment picked up and carried within the flow of water
What is solution?
Dissolved load- chemicals dissolved in the water, transported and precipitated elsewhere.Plays an important role in the carbon cycle, transferring and redepositing carbon in the oceans.
What are the characteristics of swash aligned beach?
Tend to form in low energy environments such as bays that are affected by waves roughly parallel to the shore
What are the characteristics of a drift aligned beach?
Form where the waves approach the coast at an angle.. Longshore drift moves sediment along the beach, often cumulating in the shape of a spit, a sediment sink or store. Sediment may be graded along a drift aligned beach. Finer shingle particles are likely to be carried further by longshore drift and and also to become increasingly rounded as they move.
What is a spit?
A long narrow feature made of and or shingle, that extends from the land into the sea. Spits form on drift aligned beaches. Sand or shingle is moved along the coast by longshore drift, but if the coastline suddenly changes direction, sediment begins to build up across the estuary mouth and a spit will form. . The end of the spit will also begin to curve round as wave refraction carries material round into the more sheltered water behind the spit. A 'compound spit' occurs where the transport processes are variable over time which produces a series of 'barbs along the spit'
What is a tombolo?
A beach that has formed between a small island and the mainland. Deposition occurs where waves lose their lose their energy and the tombolo begins to build up. Tombolo's may be covered at high tide
What is an offshore bar?
Submerged ridges of sand or course sediment created by waves offshore from the coast. Destructive waves erode sand from the beach with their strong backwash and deposit it offshore. Offshore bars act as both sediment sinks and sediment input stores. They can absorb wave energy thereby reducing the impacts of waves on the coastline.
Where do steep cliffs tend to occur?
-where the rock is strong and resistant to erosion, such as most igneous and metamorphous rocks
-sedimentary rocks that are dipping steeply or even vertically tend to produce steep and dramatic cliffs, as with the absence of a beach and exposed orientation with a long fetch and high energy waves that encourage erosion and undercutting by the sea
Where do gentle cliffs tend to occur?
-weak or unconsolidated rocks that are prone to slumping
-rocks that are dipping towards the sea also tend to have low-angle cliffs
-a sheltered location with low energy waves and a short fetch will result in subaerial debris building up at the foot if a cliff, reducing its overall angle
-a wide beach will absorb wave energy preventing significant undercutting and steepening
What does the rate of retreat on a cliff depend on?
-the balance of marine factors:
e.g *wave energy
*presence of a beach
-terrestrial factors such as sub-aerial processes:
The most rapidly retreating retreating beaches seem to be composed of very weak rock such as the glacial till cliffs of the Holderness coast
What characteristics relate to lithology?
Lithology: what is Strata?
Layers of rock
Lithology: what are bedding planes?
Horizontal, natural breaks in the strata, caused by gaps in time during periods of rock rock formation
Lithology: what are joints?
Vertical fractures caused either by contraction as sedimentary dry out or by earth movements during uplift
Lithology: what are folds?
Formed by pressure during tectonic activity, which makes rocks buckle and crumple (e.g the Lulworth crumple)
Lithology: what are faults?
Formed when the stress or pressure to which a rock is subjected, exceeds it's internal strength (causing it to fracture). The faults then slip or move along fault planes
Lithology: what is a dip?
Refers to the angle at which rock strata lie (horizontally, vertically, dipping towards the sea, or dipping inland)
Beach profiles: why do larger pebbles tend to be at the top of a beach?
As constructive waves will carry a range of sediment sizes up a beach due to the strong backwash, but due to the water percolating in the beach, the weaker backwash will only be able to drag back the smaller pebbles. Over time this leads to the pebbles being sorted with large at the top to smaller at the bottom
Beach profiles: why do pebbles at the bottom of the beach tend to be more rounded?
Due to the constant action of the waves causing abrasion and attrition
Beach profiles: why are most of the angular pebbles at the top of a beach?
Due to scree falling off a cliff face
How do seasonal changes in wave type create summer and winter profiles?
-Sediment is dragged offshore by destructive waves in winter
-Sediment is returned by constructive waves in summer
Why are beach profiles steeper in summer?
-as waves are more constructive than destructive
-constructive waves are less frequent and have a longer wavelength per minute, so wave energy dissipates and deposits over a wide area (weakening the backwash)
How frequent are constructive waves per minute?
6-9 per minute
How do destructive waves in winter create a different beach profile to constructive waves in the summer?
-in winter destructive waves occur at a higher frequency
-Berms may be eroded by plunging waves and high energy swash crashing down onto the beach
-strong backwash transports sediment offshore (depositing it as offshore bars)
-sometimes the backwash exerts a rip current, or undertow, dragging sediment back as the next wave arrives over the top
How frequent are destructive waves per minute?
11 to 16 per minute
What is a barrier beach?
Where a beach or spit extends across a bay to join two headlands, it forms a barrier beach or bar
When were barrier beaches and bars on the south coast of England believed to have deposited?
Following rising sea levels after the last glacial period
Give examples of large scale barrier islands
-along the coast of the Netherlands
-In North America along the South Texas coast
What prerequisites are required in order for sand dunes to form?
-large quantities of available sand, washed onshore by constructive waves (an offshore sand bar is an ideal source of sand)
-large tidal range, creating a large exposure of sand that can dry out at low tide
-dominant onshore winds, that will blow dried sand to the back of the beach
How do dunes develop?
Where sand is initially trapped by debris towards the bark of the beach
How does vegetation succession occur
-dunes develop (due to sand being trapped by debris towards the back of the beach)
-vegetation helps to stabilise the sand and eventually dunes develop
-over a period of several hundred years a transformation occurs known as vegetation succession
What are the first colonising plants known as?
Give examples of how pioneer species have special adaptations to help them survive in hostile conditions
-Plants such as sea rocket and couch grass are able to cope with very dry, salty and exposed conditions
-when they die, the plants add important organic matter to the developing soil
What are fore dunes?
Low sand dunes, formed when pioneer plants bind the sand
What is a typical species found in fore dunes?
How is Marram grass well adapted?
-what is the growth of Marram grass stimulated by?
-with long tap roots to seek water
-the growth of marram grass is stimulated by burial and its tangle of lateral roots is perfect for binding sand
What is the climatic climax community?
-as the environment changes over time, different species colonise the sand dunes until they become stable
-the final community will be adjusted to the climatic conditions of the area
What are saltmarshes?
Areas of flat, silty sediments that accumulate around estuaries or lagoons
What 3 types of environment do saltmarshes develop in?
1.) In sheltered areas where deposition occurs (e.g in the lee of a spit)
2.) Where salt and freshwater meet (e.g estuaries)
3.) Where there are no strong tides or currents to prevent sediment deposition and accumulation
Describe salt marsh formation and plant succession
1.) As mudflats develop, salt-tolerant plants (such as eelgrass) begin to colonise and stabilise them
2.)Halophytes (salt-tolerant species) such as glasswort and cordgrass help to stop tidal flow and trap more mud and silt
3.) As sediment accumulates the surface becomes drier. Different plants begin to colonise (such as sea asters and meadow grass)
4.)Creeks (created by water flowing across the estuary a low tide) divide up the salt marsh
Describe salt marsh formation and plant succession: in more detail: step 1.
-To begin with, mud is deposited close to a high tide line dropping out of the water by a process known as flocculation
-This involves the tiny individual particles of clay (mud) such that their combines mass enables them to sink in the seabed
Describe salt marsh formation and plant succession: in more detail: step 2.
-As with sand dunes, pioneer plants such as eelgrass and cordgrass start to colonise the transition zone between high and low tide
-These plants can tolerate inundation by salty water and they also help to trap further deposits of mud
Describe salt marsh formation and plant succession: in more detail: step 3.
Gradually the mud levels rise above high tide and a lower salt marsh develops with a wider range of plants that no longer need to be adapted to salty conditions
Describe salt marsh formation and plant succession: in more detail: step 4.
Soil conditions improve and the vegetation succession begins to form a meadow
Describe salt marsh formation and plant succession: in more detail: step 5.
Eventually, shrubs and trees will colonise the area as the succession reaches its climatic climax
What are the two main causes of sea level change?
What is isostatic change?
When the land rises or falls, relative to the sea
What is eustatic change?
When the sea itself rises or falls
Is eustatic change local or global?
Is isostatic change local or global?
Describe eustatic change
-in cold glacial periods, precipitation falls as snow (rather than rain) and forms huge ice sheets that store water that is usually held in the oceans
-as a result sea levels fall. As temperatures rise at the end of glacial periods, the ice sheets begin to melt and retreat.
-their stored water then flows into the rivers and sea, and sea levels rise
Describe isostatic change
-during glacial periods, the enormous weight of the ice sheets (which can be several kilometres thick) make the land sink: isostatic subsidence
-as the ice begins to melt at the end of the glacial period , the reduced weight of the ice causes the land to readjust and rise: isostatic recovery
Describe how in the UK isostatic change is because of a pivotal motion
-lands in the north and west (which was covered by ice sheets during the ice age ) is still rising as a result of isostatic recovery
-lands in the south and east (which the ice sheets never covered) is sinking. Rivers pour water and sediment into the thames estuary and the English Chanel. The weight of this sediment causes the crust to sink and relative sea levels to rise. Therefore south-east England faces increased flood risks, not only as a result of isostatic change but also as a result of rising sea levels as a result of rising sea levels caused by global warming
Describe how past tectonic activity has had an impact on some coasts across the world as well as on sea levels
1.)the uplift of mountain ranges and coastal land at destructive and collision plate margins that resulted in a relative fall in sea levels in some parts of the world
2.)local tilting of land at destructive margins e.g some ancient mediterranean ports have been submerged and others have been stranded above the current sea level
What is an emergent coastline?
Where a fall in sea level exposes land previously covered by the sea
What is a submergent coastline?
Where a rise in sea level floods the coast
What is a coastal landform associated with emergent coastlines
How are raised beaches formed?
As the land rose as a result of isostatic recovery, former wave-cut platforms and their beaches were raised above sea level
Where are raised beaches common?
On the west coast of Scotland , where remains of eroded cliff lines (called relic cliffs) can often be found behind the raised beach, with wave-cut notches and caves as evidence of past marine erosion
What are two coastal landforms associated with submergent landforms
How do rias form?
When valleys in a dissected upland area are flooded
Where are rias commonly found?
In south-west England, where sea levels rose after the last ice age, the lower parts of many rivers and tributaries were drowned to form rias
Give an example of rias
The Kingsbridge estuary in Devon- it provides a natural harbour with the deepest water at it's mouth
What are rias?
Sheltered winding inlets with irregular shorelines
How are Fjords formed?
When deep glacial troughs are flooded by a rise in sea level
What are the nature of Fjords?
They are long and steep sided with a U-shaped cross section and hanging valleys
How are Fjords different to rias?
They are much deeper inland than they are at the coast-the shallower entrance marks where the glacier left the valley
Give examples of where Fjords can be found
Norway, Chile and New Zealand
What are Dalmatian coasts?
Distinctive submergent coasts that form in a landscape of ridges and valleys running parallel to the coast
How are Dalmatian coast's formed?
When the sea levels rise, the valleys flood, although the tops of the ridges still remain exposed, forming a series of islands running parallel to the coast
Give an example of a Dalmatian coast
The Dalmatian coast in Croatia
What have the IPCC found out?
According to the IPCC sea levels stabilised about 3000 years ago and they have changed very little since that time until very recently
From the late 19th century to the late 20th century- globally how much did sea levels rise by?
About 1.7mm a year
By 2100 what does the IPCC estimate the sea levels to have risen by?
Between 30cm and 1m from current levels
Sea level rise: Between 1880 and 2010 what did global temperatures rise by?
By an average of 0.85 degrees
What is sea level rise primarily due to?
-the thermal expansion of water
-due to heating
-the melting of freshwater ice such as the Greenland and Antarctic ice sheets and mountain glaciers
What are the two types of costs and benefits?
Cost-benefit analysis: What does tangible mean?
Where costs and benefits are known and can be given monetary value (e.g building costs)
Cost-benefit analysis: What does intangible mean?
Where costs may be difficult to assess but are important (e.g the visual impact of revetment)
What are the advantages of groynes?
-work with natural processes to build up beach which inc. tourist potential and protects land behind it
-not too expensive
What are the disadvantages of groynes?
-starve beaches further along the coast of fresh sediment (because they interrupt LSD) often leading to inc. erosion elsewhere
-unnatural and can be unattractive
What is the cost of groynes?
£5,000 to £10,000 each (at 200 metre intervals)
What are the advantages of sea walls?
-effective prevention of erosion
-they often have a promenade for people to walk along
What are the disadvantages of sea walls?
-they reflect wave energy rather than absorbing it
-they can be intrusive and unnatural looking
-they are very expensive to build and maintain
What is the cost of sea walls?
What are the advantages of rip rap (rock armour)?
-often used for recreation e.g fishing, sunbathing
-relatively cheap and easy to construct and maintain
What are the disadvantages of rip rap (rock armour)?
-can be intrusive
-the rocks are usually not local and can look out of place with local geology
-can be dangerous for people clambering over them
What is the cost of rip rap (rock armour)?
£100,000 to £300,000 per 100m
What are revetments?
Sloping wooden concrete or rock structures placed at the foot of a cliff or top of a beach. They break up the waves energy
What are the advantages of revetments?
They are relatively inexpensive to build
What are the disadvantages of revetments?
-intrusive and very unnatural looking
-they need high levels of maintenance
What is the cost of revetments?
up to £4,500/m
What is an offshore breakwater?
A partly submerged rock barrier, designed to break up the waves before they reach the coast
What are the advantages of offshore breakwaters?
An effective permeable barrier
What are the disadvantages of offshore breakwaters
Visually unappealing and a potential navigation hazard
What is the cost of offshore breakwaters?
Similar to rock armour-depending on the materials used
What are the advantages of beach nourishment?
-relatively cheap and easy to maintain
-it looks natural and blends in with the existing beach
-it inc. tourist potential by creating a bigger beach
What are the disadvantages of beach nourishment?
-needs constant maintenance because of the natural processes of erosion and LSD
What are the costs of beach nourishment?
What is cliff regrading and drainage?
-cliff regrading reduces the angle of a beach to help stabilise it
-drainage removes water to prevent landslides and slumping
What are the advantages of cliff regrading and drainage?
-drainage is cost-effective
-can be effective on clay or loose rock where other methods will not work
What are the disadvantages of cliff regrading and drainage?
-regrading effectively causes the cliff to retreat
-drained cliffs can lead to collapse (rock falls)
What is the cost of cliff regrading and drainage?
Cost is variable
What is dune stabilisation?
-Marram grass can be planted to stabilise the dunes
-Areas can be fenced in to keep people of newly planted areas
What are the advantages of dune stabilisation?
-maintains a natural coastal environment
-provides important wildlife habitats
-relatively cheap and sustainable
What are the disadvantages of dune stabilisation?
-time consuming to plant marram grass
-people may respond negatively to being kept off certain areas
What are the costs of dune stabilisation?
£200 to £2000 per 100m
What are the advantages of marsh creation?
-relatively cheap (land reverts back to it's original state before management)
-creates a natural buffer to powerful waves
-creates an important wildlife habitat
What are the disadvantages of marsh creation?
-agricultural land is lost
-farmers or landowners need to be compensated
What do shoreline management plans identify?
The natural processes, human activities and management decisions
What are shoreline management plans?
Extremely detailed, comprehensive documents and are based on the sediment cell principle that intervention will be largely self-contained within each cell, having no knock on effects elsewhere
SMP's: What are each sediment cells treated as?
A 'closed cell'
Shoreline management plans:What are the 4 options considered for any stretch of coastline?
1.) Hold the line-maintaining the current position of the coastline (often using hard-engineering strategies)
2.) Advance the line- extending the coastline out to sea (by encouraging the build up of a wider beach, using beach nourishment methods and groin construction)
3.)Managed retreat/strategic realignment- allowing the coast to retreat in a managed way (e.g creating salt marsh environments by deliberately breaching flood banks that protect low-quality farmland)
4.)Do nothing/no active intervention- letting nature take it's course and allowing the sea to erode cliffs and flood low lying land and allowing existing defences to collapse
What is Integrated coastal zone management?
The process that brings together all of those involved in the development, management and use of the coast
What is the aim of Integrated coastal zone management?
To establish sustainable levels of economic and social activity; resolve environmental, social and economic challenges and conflicts; and protect the coastal environment
What does the move to adopt an ntegrated coastal zone management mean?
-That complete sections of the coast are being managed as a whole rather than by individual towns or villages
-This is because human actions in one place affect other places further along the coast
-Essentially this is because of the transfers (flows) within the sediment cell, moving sediment from one place to another
-What is eroded from one location eventually becomes a protected beach somewhere else