Coasts Revision Flashcards
(134 cards)
1
Q
What is the littoral zone and how can it change?
A
The area of the coast that can be affected by wave action.
It is a dynamic zone which means its constantly changing due to the interaction between processes on land and in the sea.
These changes can be:
- Long - term due to climate or sea level changes
- Short term due to the tides, waves, and storms
2
Q
What are the four parts of the littoral zone?
A
- Backshore is usually beyond the influence of wave action but can be affected during storm events
- Foreshore is the intertidal area between high and low tide
- Nearshore is the breaker zone where friction between the seabed and the waves causes them to break
- Offshore is the area outside the influence of waves
3
Q
What are concordant coasts?
A
A concordant coastline is a coastline where the same type of rock runs parallel to the coast, and the layers of rock are folded into ridges.
Concordant coastlines are also known as longitudinal or Pacific type coastlines
Example: Durlston Bay and Dalmatian and Haff coastlines
4
Q
What are discordant coasts
A
A discordant coastline is a coastline where bands of different rock types run perpendicular to the coast, resulting in the formation of headlands and bays
Discordant coasts are also known as Atlantic coasts
Example: Lulworth cove
5
Q
Eustatic sea level change
A
Eustatic sea level change is a global change in the amount of water in the oceans or the shape of the ocean basins.
Caused by:
1. Changes in ocean water volume and temperature = Impact seen in tropical oceans/meltoing of ice caps
2. Tectonic activity
3. Thermal expansion
6
Q
What is Isostatic sea level change?
A
Isostatic sea level change is a local/regional change in sea level that occurs when the land rises or subsides relative to the water
May be due to:
- Post-glacial adjustment
- Accretion
- Subsidence
- Tectonics
The Earth’s crust floats on a denser underlying layer (asthenosphere), which is in balance when the weight of the crust is exactly balanced by its buoyancy
The addition of a load at a particular point of the crust (water, ice or increasing sediment at a delta) upsets the equilibrium and some of the asthenosphere floats away, causing isostatic depression as the land level falls
7
Q
What are Emergent Coasts?
A
Emergent coastlines are coastlines that have been created when the sea level has fallen relative to the land. This can happen when the land is uplifted or when the sea level falls
8
Q
What are Submergent Coasts?
A
Coastlines that have been submerged underwater due to a rise in sea level.
They are the result of areas of land that were once part of the terrestrial land being inundated by the sea
9
Q
What are the characteristics of a high energy coast?
A
- Destructive waves
- Exposed to strong winds and long fetches
- Higher rates of erosion and deposition
- Tend to be rocky coasts
- Steep cliffs - marine cliff profile
- Less steep cliffs - subaerial cliff profile
Headlands, wave - cut platforms
10
Q
What are the characteristics of a low energy coast?
A
- Constructive waves
- Sheltered locations with short fetch
- Higher rates of deposition than erosion
- Sandy beaches, salt marshes, estuarine and tidal mud flats
- Gentle relief
- Sediment from land and sea
Beaches, spits, coastal plains
11
Q
Why do coastal plains occur?
A
They usually occur where the land gradually slopes down towards the sea, tend to be low relief
Coastal plains include both:
- Sandy coastlines
- Estuarine coastlines
12
Q
What are primary coasts?
A
dominated by land-based processes, such as deposition from rivers
13
Q
What are secondary coasts?
A
dominated by marine erosion or deposition processes
14
Q
Wave tide types?
A
Microtidal coasts – have a tidal range of 0-2m
Mesotidal coasts – have a tidal range of 2-4m
Macrotidal coasts – tidal range greater than 4m
15
Q
What are Dalmatian coastlines named after and how do they form?
A
Named after the Dalmatian region of Croatia.
Formed as a result of tectonic forces and sea level rise
Tectonic activity forms anticlines and syncline which run parallel to the sea
Sea level rise after the Devensian Glacial then flooded the synclines leaving the anticlines standing above the water
The result is a series of islands which run parallel to the coast
Feature long islands and coastal inlets that run parallel to the coastline.
Normally occur in high energy environments from where there is eustatic or isostatic change creating a submerging coastline.
16
Q
Haff coastlines?
A
Located along the southern Baltic coastline and named after the Haffs, or lagoons, of the southern shore of the Baltic Sea.
Characterized by long spits of sand that run parallel to the low coast.
During the Devensian Glacial large amounts of sand and gravel were deposited offshore
After the glacial period had ended the material was then deposited nearer to the land by constructive waves
This formed bars across bays and river mouths trapping the water behind to form a lagoon (Haff)
These are a feature of low-energy coastlines
17
Q
What is differential erosion?
A
The difference in rates of erosion due to some rock types being more resistant than others. More resistant rocks erode more slowly than less resistant rocks
18
Q
What are the 4 processes of erosion?
A
Hydraulic action - the most powerful (affects rocks of all resistance)
Abrasion - needs looser sediment to be effective, or soft sedimentary rocks
Attrition - only acts on already eroded sediment - soft sedimentaries are easily rounded
Solution - mainly affects limestone, which is vulnerable to solution by weak acids
19
Q
What is flocculation?
A
when very small clay particles clump together in the water (in suspension) and eventually become large enough to sink.
20
Q
What are the different weathering types?
A
Mechanical weathering processes include freeze - thaw and salt crystallisation
Chemical weathering includes solution (carbonation)
Biological weathering includes plant roots and animal activity
21
Q
What are the different types of mass movement?
A
Landslide: A rapid downslope movement of large blocks of rock and soil along a line of weakness in the rock, such as a fault. Landslides are common on steep slopes and in areas where rocks are being undercut.
Mudflow: A slow or rapid flow of saturated soil down a slope. Mudflows can be destructive when they reach plains or piedmonts, and are common near erupting volcanoes.
Slump: A type of slide where a mass of earthen material moves downslope in one piece. Slumps often occur when clay-rich soil becomes saturated and slippery.
Rockfall: Bits of rock fall off a cliff face, usually due to freeze-thaw weathering.
Rotational slip: Saturated soil slumps down a curved surface.
22
Q
What is isostatic rebound?
A
Isostatic rebound occurs for example, when an ice sheet melts and the land slowly starts to rise again as the huge weight has gone (happening in SE England now) this is known as glacio-isostasy
23
Q
What are glacioeustasy or glacio-eustatic changes?
A
It’s when ice sheets melt causing rising global sea levels
24
Q
What are examples of emergent landforms?
A
Landforms that exist because of a reduction in sea level are called emergent landforms
This happens during isostatic recovery
When land rebounds through isostatic recovery landforms which are the result of previous sea levels are revealed including:
Raised beaches (formed when sea levels were much higher than now)
These are:
Beaches which are above high tide level
They are flat and covered by sand/pebbles
Experience succession
Raised beaches can be seen on the Scottish islands of Islay, Jura, Colonsay and Mull
Fossil cliffs
This is a:
Steep slope at the back of a raised beach
Wave-cut notches, caves, and arches may be evident
25
What are examples of submergent landforms?
This happens when coastlines are flooded
Rias (river valleys drowned after sea ice melts)
River Fowey estuary in Cornwall
fjords (drowned glacial valleys) in Norway
Dalmatian coast is a submergent landform
26
Who will sea level rise affect?
Sea level rise may affect a different number of people due to:
Different populations in low lying coastlines
Can be ideal for agricultural fertility
27
Why do sea levels rise?
Melting glaciers and ice sheets: As glaciers and ice sheets melt, they add water to the ocean.
Thermal expansion: As the ocean warms, its water expands.
Changes in land-water storage: Changes in the amount of water stored in lakes, rivers, aquifers, and reservoirs, as well as changes in precipitation patterns, can contribute to sea level rise.
Vertical land motion: The Earth's crust rebounds and subsides, which can affect sea levels.
Human activities: Human activities, such as burning fossil fuels, are the main driver of climate change.
28
What are erosional processes?
Erosional processes refer to how natural forces like water, wind, ice, and biological activity wear away the Earth's surface.
29
What are mass movement processes?
Mass movement refers to the downslope movement of rock, soil, and debris due to gravity.
30
How many types of erosional processes are there?
6
31
What are the types of erosional processes?
Hydraulic Action: The force of moving water that breaks down rocks.
Abrasion: Rocks or sediment scrape against surfaces, wearing them down.
Attrition: Rocks and pebbles collide and break into smaller, smoother pieces.
Corrosion: Chemical dissolution of rocks, especially limestone, by acidic water.
Solution: Rocks dissolve directly in water, particularly limestone in coastal and river environments.
Wind Erosion: Wind removes fine particles (deflation) or wears down rock surfaces (abrasion).
These processes shape various landforms, such as cliffs, valleys, waterfalls, caves, and glacial features.
32
How many types of mass movement processes are there?
6
33
What are the types of mass movement processes?
Soil Creep: Slow, gradual movement of soil down a slope due to freezing/thawing or plant growth.
Mudflow: Rapid flow of water-saturated soil and debris, often after heavy rain.
Landslides: Sudden, rapid movement of large masses of rock and debris, triggered by rain, earthquakes, or human activity.
Rockfall: The rapid fall of rocks from steep slopes, often due to freeze-thaw weathering.
Slump: A downward, rotational movement of a section of slope, often caused by erosion or water.
Debris Flow: A fast-moving flow of rocks, soil, and water, more destructive than mudflows.
Factors influencing mass movement include water, slope angle, vegetation, and human activity. These processes create landforms such as scarps, talus slopes, and debris cones.
34
What landforms are form at emergent coasts?
Forms:
1. Raised beach = is a flat, sandy or pebble-covered beach that sits above the current sea level
2. Fossil cliffs = is a steep slope at the back of a raised beach that was formed by marine erosion but is now above high tide
35
What are types of depositional landforms?
1. Spit = A beach spit is a long, narrow ridge of sand or shingle that extends from the land into the sea (Example = Holderness coast)
Caused by:
Longshore drift: Longshore drift carries sediment along the coastline in a zig-zag pattern.
Deposition: When the coastline changes direction, the energy of the longshore drift disperses, causing deposition on the sea bed.
2. Sand Dune = A dune is a natural hill or ridge made of sand that forms when wind blows sand into a sheltered area
Formation:
Sand dunes are formed when wind blows sand off the beach and deposits it around an obstacle, like a rock or driftwood. The sand builds up into ridges, called embryo dunes, that grow in size over time
Stabilization
Vegetation, such as marram grass, stabilizes the dunes through a process called plant succession.
Conditions
Sand dunes form where the rate of beach deposition is greater than erosion. The stronger the wind, the higher the dunes will be.
3. Bayhead beach (Lulworth cove)
Swash - aligned feature = where waves break parallel to the shoreline and move sediment into a bay, where a beach forms. Erosion is concentrated at headlands and the bay is an area of deposition
36
Why does deposition occur?
Deposition occurs when waves no longer have sufficient energy to continue to transport material
This loss of energy might be due to:
- the wind dropping, removing an energy source
- resistance by obstruction, e.g. a groyne or headland
- dissipation of energy through refraction
- friction from extended transport across shallow angled nearshore and foreshore zone
Sediment is deposited when the force transporting the sediment drops.
- Deposition occurs in two main ways:
Gravity settling occurs when the energy of transporting water becomes too low to move sediment. Large sediment will be deposited first, followed by smaller sediment (pebbles -> sand -> silt)
37
What is flocculation?
Flocculation
This process is important for very small particles, like clay, which clump together and become large enough to sink
- Flocculuation is a depositional process that is important for very small particles, such as clay, which are so small that they will remain suspended in water. Clay particles clump together through electrical or chemical attration, and become large enough to sink.
38
What landforms are created by weathering?
Forms:
1. Talus scree (St Oswald's slope)= A mass of small loose stones that form or cover a slope on a mountain due to:
Mechanical weathering, in particular:
Freeze-thaw weathering
A type of erosion that occurs when water enters cracks in rocks and freezes, causing the crack to widen. This process continues until the rock breaks causing blackballs
2. Rotational scar slope = The scar left behind due to rotational slump
Chemical weathering when heavy rain reacts with permeable minerals in rocks and saturates them leading to material coming away from the cliff face
3. A terraced cliff profile = a stepped cliff face that's created by eroded rocks and fractures or lithology in the rock.
39
How does the coast act as a system?
As with any geographical system, the coast, as a system, has inputs, stores, transfers and outputs
The system constantly strives to be in a state of dynamic equilibrium
The coast can be viewed as both an open system and a closed system
It is an open system because it receives inputs from the lithosphere, atmosphere, hydrosphere, biosphere and cryosphere
However, during research and coastline management the coast can be seen as a closed system where a specific sediment cell is examined
40
What are examples of positive feedback at the coast?
As waves erode the cliff, material is released
This material abrades the cliff which results in even more cliff erosion
41
What are examples of negative feedback at the coast?
As the shore is eroded, the material makes the wave-cut platform wider
This can absorb wave energy and reduce the impact at the base of the cliff
42
What examples of geology?
Characteristics of the land:
Rock type
Rock structure
Coasts can be classified as:
Rocky
Sandy
Estuarine
They can also be classified as:
Concordant - where different rock types run parallel to the coast
Discordant - where different rock types run at right angles to the coast
43
What can sea level change occur as a result of?
Global warming - natural and enhanced
Tectonic activity - which can lead sections of land to rise or subside
Longer-term sea level change can be:
Eustatic - when the sea level itself changes
Isostatic - when the land rises or falls relative to the sea
This leads to coasts that are either emergent or submergent
44
What are examples of short term processes at the coast?
Coasts can also be categorised by short-term factors:
Waves - can be constructive or destructive
Tides - tidal range is the difference between high and low tide
Rivers
Storm events
These create coastlines that can be:
Retreating or advancing which depends on whether erosion or deposition dominates
Dominated by land-based processes (primary coasts) or marine processes (secondary coasts)
Large or small tidal range
High or low-energy
45
Why do rocky coasts form?
Rocky coasts form where there is more resistant geology - in the UK this is mainly in the north and west of the country
Cliffs of varying heights and steepness can be found along rocky coastlines:
Steep cliffs tend to be found in high energy environments
Cliffs with a gentler slope tend to be found in low energy environments
Erosion is more dominant than deposition
Two types of erosion may dominate along rocky coastlines:
Marine erosion - the action of waves
Sub-aerial erosion - weathering and mass movement
46
What is coastal morphology?
The shape and form of the coastline is known as coastal morphology
This is influenced by the rock type (geology) and structure
47
What does geological structure refer to?
the way that rocks are folded or tilted - this is known as its lithology
48
What are Strata?
Layers of rock
49
What are Bedding planes?
Horizontal cracks created by pauses in rock formation
50
What is a Joint?
Vertical cracks caused by tectonic movement or contraction
51
What is a Fold?
The result of pressure during tectonic movement causing the rock strata to fold
52
What is a Fault?
The result of stress or pressure causing it to fracture
53
What is a Dip?
The angle of the rock strata
54
How do Sedimentary rocks form?
As a result of compaction and cementation of sediment called lithification
Examples of sedimentary rocks include shales, sandstone, and limestone
Least resistant
Sedimentary rocks:
- Erode and weather more rapidly than other types of rock
- Form in layers
- Have weak bedding planes
- They are clastic which means they are made of clasts (sediment particles)
- Are heavily jointed
- Often have many bedding planes and fractures
55
How do Metamorphic rocks form?
Form when sedimentary and igneous rocks are altered through heat and pressure, but do not melt in the process
Examples of metamorphic rocks include slate and marble
Metamorphic rocks:
- Have a crystalline structure
- Are often folded and faulted
Are more resistant than sedimentary rock and igneous rocks
- The crystals have a parallel arrangement (foliation) which means they are weaker than igneous rocks
56
How do Igneous rocks form?
Form when molten rock from the Earth's mantle cools and hardens
Examples of igneous rocks include granite and basalt
Second most resistant
Igneous rocks:
- Erode and weather very slowly
- Can be categorised into two types:
Intrusive igneous rock - forms within the ground, cools slowly, and has large course crystals
Extrusive igneous rock - forms on the Earth's surface, and cools quickly, forming smaller crystals
- Has interlocking crystals
- Fewer joints and weaknesses than in other rocks
57
What are different wave characteristics?
- Wave height is the distance from the peak to the trough
- Wave length is the distance from crest to crest
- Wave frequency is the number of waves which pass a specific point over a given time
58
What is the fetch of a wave?
The distance of open water the wind blows over
59
What is the strength of a wave?
How forceful the wind is. determined by the pressure difference
60
What does the duration of a wave refer to?
How long the wind has been blowing
61
What are the two types of waves?
Constructive
Destructive
62
What are the different ways material is moved in the water?
Traction = heavy material rolled/dragged on sea floor
Saltation = material bounces on river bed
Suspension = suspended within river flow
Solution = dissolve in the water and are carried along
63
What is a current?
The flow of water in a specific direction which transports sediment
Surface currents are formed mainly by wind
Deepwater currents are also called thermohaline circulation and are caused by density differences
64
What is the difference between high and low tide known as?
The tidal range
65
What processes happen at Sub-aerial cliffs?
Weathering and mass movement
66
What is a rotational scar?
A rotational scar is:
Curved
Un-weathered
Un-vegetated
Forms as a result of rotational slumping
The section that has detached is at the base of the cliff often with vegetation attached
67
What is a talus scree slope?
A talus scree slope is a fan-shaped mound of material
Made of block-fall debris which has accumulated at the foot of a cliff
Often, they have a concave profile
68
What is a terraced cliff profile?
The profile of the cliff is stepped
This is the result of the lithology or fractures in the rock
69
What landforms do mass movement create?
Mass movement creates distinctive landforms including:
Rotational scars
Talus scree slopes
Terraced cliff profiles
70
What is Post-glacial adjustment?
- Post-glacial adjustment = During a period of glaciation, extremely heavy icy sheets weigh land down
When the glacial period ends and the ice melts the land will rebound to a higher level, lowering the sea level in a process known as isostatic recovery or readjustment
71
What is accretion?
- Accretion = Within the sediment cell, there are areas of net deposition causing land to build up
72
What is subsidence?
- Subsidence = Caused by the lowering of the water table or increased deposition weighing down the sediment
73
How does tectonic activity impact isostatic change?
- Tectonics = The folding of the sedimentary rock + Lava and ash from volcanoes increase the height of the land relative to the sea level
74
How is the UK is still experiencing isostatic recovery from the end of the last ice age?
Land in the north in Scotland is still rebounding and rising by approximately 1.5mm a year
Lands end in Cornwall is sinking by 1.1mm each year
75
What human actions impact the threat of coastal retreat and coastal recession?
Dredging = The removal of sediment from rivers or the sea
This impacts on the amount of sediment being deposited at the coast
Dams
- traps river sediment behind the dam wall
- It is estimated 100 billion tonnes of sediment is stored behind the world's dams and this increases by a billion tonnes each year = this starves the coast of sediment
- It is estimated that dams on the river Ebro in Spain have led to a 93% reduction in sediment downstream
- The reduction of sediment supplied to the coast due to dams and dredging leads to greater coastal erosion because:
1. Beaches decrease in size as they are not being supplied with sediment
2. Destructive waves have more impact by increasing the rate of coastal erosion
Coastal management
- affects the rate of erosion
- In some areas coastal defences such as in places like Hornsea sea walls and rip rap reduce the amount of erosion
- This slows recession of the coast
In other areas coastal management affects the movement of sediment
- Groynes at Hornsea on the Holderness coast reduce longshore drift
- This starves areas down the coast such as Mappleton of sediment also known as terminal groyne syndrome
- As with dams and dredging the reduced supply of sediment decreases beach size and increases the impact of destructive waves
76
What physical actions impact the rates of coastal recession?
Sub-aerial processes
Wind direction and fetch
Tides
Seasons
Weather systems
Storms
77
Are rates of recession constant?
No
78
What local factors increase flood risk?
Height of land
Degree of subsidence
Vegetation removal
79
What are some facts and examples of countries and regions sitting on low lying land?
Globally, almost 300 million people live in coastal areas below 2m
Of the 10 world's largest cities, 8 are in coastal areas
Countries and regions which are particularly low-lying include:
Bangladesh - over 10% of the land is 1m or less above sea level
Maldives - has an average height of 2m above sea level with highest point being 2.4m
Netherlands - 27% of the country is below sea level and protected by sea defences
80
What does the degree of subsidence refer to?
Coastal areas are vulnerable to subsidence particularly deltas and land reclaimed from the sea
Clearing land for agriculture and ground water abstraction, increases the risk of subsidence
Building of settlements, along with the weight of the buildings, increases the risk of subsidence
When subsidence occurs, the land is then lower and more vulnerable to coastal flooding
81
How does vegetation removal affect the risk of floods?
The removal of vegetation, including salt marshes and mangroves, increases coastal flood risk
It is estimated that 50% of salt marshes and 35% of mangroves have been lost since the 1950s due to:
- Reclamation for development - housing and transport
- Coastal management such as sea walls
- Tourism, to create beaches with open views to the sea
- Shrimp farming
Where vegetation exists, it significantly impacts wave height, which reduces the risk of flooding:
- In the UK, salt marshes are estimated to reduce wave height by up to 80%
- 100m of mangroves is estimated to reduce wave height by between 13-66%
The vegetation:
- Traps sediment, which helps to increase the land height
- Reduces the impact of waves and erosion because, it absorbs the wave energy
82
How does the height of land affect the rates of coastal flooding?
Low lying areas are more vulnerable to rising sea levels and storm surges
Storm surges and spring tides leads to water flooding areas of the back-shore and beyond
83
What global factors increase flood risk?
Storm surges
Depressions
Tropical cyclones
Climate change
Increased storm magnitude and frequency
84
How can storm surges increase flood risk?
A storm surge is a rise in the sea level as a result of a storm or tropical cyclone and affect approximately 1.5 million people a year
Storm surge events can lead to severe coastal flooding with dramatic short-term impacts
Storm surges are caused by:
- Depressions (low pressure) leading to storm events
- Tropical cyclones
Warmer ocean temperatures combined with higher sea levels are predicted to make storms and tropical cyclones more frequent and more severe
85
How can depressions affect the risk of flooding?
A depression is an area of low pressure
The low-pressure area forms due to air rising from the surface
As it rises, it cools, condenses and forms clouds, bringing rain
In the northern hemisphere, depressions move:
- West to east
- In an anticlockwise direction
Due to the low-pressure, sea levels are higher - for every 10mb decrease in pressure, the sea level is 10cm higher
This is called the inverse barometer effect
Storms are deep, active low-pressure areas, which bring strong winds and heavy rain
In the UK, when the storm is likely to have a significant impact on people and the environment, it becomes a named storm
86
How can tropical cyclones impact the risk of flooding?
A tropical cyclone is an area of very low air pressure
As in a depression, it is formed by warm rising from the ocean surface, forming towering cumulonimbus clouds, which rotate around a central eye
Tropical cyclones form in the zone between 5-30° north and south of the equator, in areas where sea temperatures are 27°C or above
A tropical cyclone brings heavy rain and strong winds
When wind speeds reach 39mph it is categorised as a tropical storm, when they reach 74mph it is a tropical cyclone
87
How can climate change impact the risk of flooding?
Climate change may increase coastal flood risk
The two main factors which increase the flood risk are:
- Global sea level rise due to warming oceans and melting ice sheets and glaciers
- Increased frequency and magnitude of storms
The pace and magnitude of this increased risk are uncertain
88
According to National Oceanic and Atmospheric Administration (NOAA) how much have global sea levels have risen since 1880?
About 21-24cm
89
The rate of sea level rise is accelerating, what was the rate in the 1900s compared to 2006?
Throughout the 1900s, the rate averaged 1.4mm a year
Since 2006, the rate has averaged 3.6mm a year
90
What are examples of economic and social losses and how do they link?
Coastal flooding can lead to loss of:
Economic = Social
Housing = Relocation
Businesses = Loss of livelihood
Agricultural land = Amenity value
Infrastructure - roads, power, water, communication
91
What does amenity value mean?
Something which has worth due to people's appreciation or enjoyment of it, such as a beautiful landscape
92
What are examples of hard engineering?
Groynes
Sea walls
Rip rap/Rock armour
Revetments
Offshore breakwater
93
What are Groynes?
Structures built perpendicular (at right angles) to the shore. Sediment is trapped as it is transported by longshore drift. The beach builds up which absorbs wave energy
94
What are Sea Walls?
Walls with a curved or stepped surface that absorb and reflect wave energy
95
What is Rip rap/Rock armour
Large concrete or granite boulders at the foot of a cliff. The spaces in between the boulders cause waves to bounce between many surfaces, reducing the energy of the wave
96
What are revetments?
A sloped or ramp like structure that breaks up wave energy
97
What is offshore breakwater?
Rock barrier a little out to sea from the shoreline. This breaks the waves and dissipates their energy before they reach the coast.
98
What is soft engineering?
Soft engineering works with natural processes and material
Soft engineering methods can be an integral part of the management strategy, in order to adapt to sea level change as well as coastal erosion, through developments such as salt marshes
99
What are examples of soft engineering?
Beach nourishment/replenishment
Cliff Regrading and Drainage
Dune stabilisation
Marsh creation
100
What is Beach nourishment/replenishment?
Adding sand or shingle to a beach to widen it - this creates more surface area to absorb wave energy
101
Cliff Regrading and Drainage
Reducing the angle of the cliff to stabilise the slope.
Drainage of water also stabilises the cliff against mass movement.
102
What is Dune stabilisatin?
Planting species like Marram grass so that the roots bind the dunes.
The dunes absorb wave energy and protect the land behind.
103
What is Marsh Creation?
This is a form of do-nothing or managed retreat.
Land is allowed to be flooded by the sea and then left to become a salt marsh.
This absorbs wave energy and also creates a buffer to rising sea level and projects higher value land.
104
What is sustainable management?
Sustainable management of the coastal zone is wider than preventing erosion
It involves a range of strategies including:
- Mitigation of flood and erosion risk using a range of techniques
- Adaptation to erosion and flood risk
- Education of local communities
- Supporting livelihoods dependent on the coastal zone such as fishing
- Monitoring of coastal changes
Integrated coastal zone management (ICZM) is based on the idea of sustainable coastal management
As well as targeting all the areas listed it also seeks to resolve conflicts which may occur
Conflicts occur as a result of sustainable management because:
- Farmers may lose productive land due to managed retreat or do-nothing policies because their land has less value than that in towns
- People may lose their homes and have to relocate in areas where the cost-benefit analysis decides the areas cannot be protected
105
What is Intergrated Coastal Zone Management (ICZM)?
The shoreline management plans in the UK are a form of ICZM
Whole sections of the coast are managed together
They recognise that the sediment (littoral) cells interact with each other and that changes in one part of the coast impact on other areas - such as the placement of groynes causing terminal groyne syndrome
ICZM involves a range of stakeholders involved in the use and management of the coast and aims to:
- Create sustainable economic and social activities
- Protect the coastal environment
- Manage flood and coastal erosion risk
- Resolve any conflicts that may occur
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What has the ICZM done in Semarang, Indonesia?
In Semarang, Indonesia ICZM has been implemented to reduce the risk of:
- Coastal flooding
- Subsidence
- Increased salinity
It is expected that these will worsen as a result of sea level rise and development in the area
Local population are dependent on fishing and are reluctant to move
Expansion of residential and industrial developments in the area has increased subsidence as a result of increased water abstraction
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What strategies have the ICZM using in Semarang?
Structural:
- Embankments
- Pumping stations
- Drainage systems
- Land reclamation
Non-structural:
- Education
- Coastal planning
Ecosystem:
- Conservation of mangrove ecosystems
- Replanting mangrove ecosystems
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What stakeholders does the ICZM include?
The stakeholders include:
National and local government
Local community
NGOs
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What is a cost-benefit analysis?
This is used to decide the recommendations for each section of coastline
Costs are forecast based on known tangible costs of coastal defences such as how much 100m of sea wall will cost to build and maintain, and intangible costs such as visual impact of the sea wall
The costs are then weighed up against the benefits for the environment and population
Where benefits outweigh costs, such as the sea wall at Bridlington protecting population of over 36,000 and buildings from coastal flooding, then the project is likely to go ahead
Where the costs outweigh the benefits, such as protecting the 24 houses at Skipsea from coastal erosion and flooding, a scheme is unlikely to be put in place
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What is a SMP?
In a Shoreline Management Plan (SMP) = each of the 11 sediment cells in the UK have had a detailed document written to identify the natural processes, activities and risks in the area
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What does DEFRA refer to?
The Department for Environment, Food and Rural Affairs = makes recommendations for all sections of the coastline
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What options do DEFRA make recommendations from?
They make recommendations from the four options:
- Hold the line: maintaining the position of the coastline using mostly hard engineering methods
- Advance the line: extending the coastline out to sea by building up the beach and land reclamation
- Managed retreat: deliberate flooding of particular areas to manage coastal retreat
- Do nothing: letting nature take its course
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When making recommendations what do DEFRA have to consider?
The value of the land and assets as well as technical viability of management strategies
This can lead to local conflict because the SMP protects some areas and not others
In Skipsea on the Holderness coastal erosion rates since 1989 have been 1.4m per year on average
People in Skipsea feel that nothing has been done to protect their village with a population of 700 whilst money has been spent on coastal defences in neighbouring towns and villages
The decisions were made as a result of cost-benefit analysis
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What do sustainable approaches require?
- Management of natural resources at the coast like water and farmland;
- Monitoring of any changes to inform new strategies and;
- Education and inclusion of the local communities to support the strategies
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How many people does coastal management affect?
Coastal management affects the lives of the 630 million people who live in coastal areas at risk of coastal flooding
The impact of coastal management creates winners and losers
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Who are the winners in the outcomes of coastal management?
- Property and businesses are protected
- The environment is conserved
- Farmland is protected
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Who are the losers in the outcomes of coastal management?
- People have to relocate
- Homes and businesses are lost
- Farmland is lost
- Habitats are destroyed
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Who are the many stakeholders involved in these conflicts?
- Homeowners
- Local authorities
- Environmental pressure groups
The impact on people can also vary depending on the level of development of a country
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What is the Devensian Glacial?
The last glacial period in Britain
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What is the practice of 'gripping'?
The practice of ‘Gripping’ (the channelization of streams) in converting
moorlands for use in arable farming has increased flood risk in
catchments such as the river Hodder.
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What is Terminal groyne syndrome?
A coastal phenomenon where groynes, structures designed to trap sediment from longshore drift, cause a buildup of sediment on one side (updrift), while the area downdrift is starved of sediment and experiences increased erosion.
This increased erosion rate is what defines the syndrome.
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What are the different types of depositional processes?
Longshore drift
Tides and currents
Wave types
Vegetation is important in stabilising sandy coastlines through dune successional development on sandy coastlines and salt marsh successional development in estuarine areas.
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What landforms are created by transportation and depositional processes?
Beaches
Recurved and double spits
Offshore bars
Barrier beaches and bars
Tombolos
Cuspate forelands which can be stabilised by plant succession
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What are human actions affecting the rates of coastal recession?
Dredging = removal of sediment
Dams = construction of dams traps river sediment behind the dam wall
Coastal management = groynes and riprap
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How is the holderness coast affected by sub-aerial processes?
The Holderness coast is predominately boulder clay
Wetting and drying
At high tide the particles expand when covered with water, at low tide they dry out and contract
Repeated wetting and drying causes the clay to crumble
Freeze-thaw
During the winter months, water enters the fractures in the boulder clay
At night this water freezes and expands - due to Arctic maritime air masses
Repeated expansion and contraction, causes the cliff to be weakened
Slumping
The Holderness coast regularly experiences wet weather
Weathering leaves cracks in the boulder clay
Water enters these cracks, causing the clay to become heavier, and lubricated (slippery)
This leads to a large area of land moving downslope in one piece - known as rotational slip
The fastest rate of coastal erosion in Europe
The rate of erosion is approximately 1.8 metres a year
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What are periods of high pressure known as?
Anticyclones
During anticyclones there are gentle winds and low waves, so rates of recession are low
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What are periods of low pressure known as?
Depressions
During depressions the winds are much stronger, leading to high waves and greater rates of recession
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What are some stats regarding economic and social losses in developed countries - UK?
Economic:
An acre of residential land in the UK has a value between £300,000 (north) to £1 million (south)
Average damages in the UK from coastal flooding is £120 million a year
An acre of farmland costs between £12,000 - £50,000
35 power stations, 22 clean water facilities and 91 sewage treatment works in the UK have been identified as at risk from coastal flooding
Social:
Up to 200,000 properties will be at risk by 2050 in the UK
Income for farmers lost due to loss of livestock and flooding of crops
Loss of jobs when businesses are affected
In 2007 in the UK, it was estimated that £48 billion worth of land with amenity value was at risk from coastal flooding before 2050
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A study in 2011 suggested that how many people could be displaced by sea level rise by 2100?
More recent studies suggest that has increased to how many more million people?
187 million
Increased to 630 million
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Lithology vs Geology
Geology refers to the broad study of the Earth's structure, processes, and history, encompassing everything from rocks and minerals to landforms and geological hazards.
Lithology, on the other hand, is a specific aspect of geology that focuses on the physical characteristics and composition of rocks themselves
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What are the three types of Marine processes?
Marine Processes:
These processes occur in the ocean and involve the interaction of water with the coastline. Key marine processes include:
Erosion: Waves break down rocks and remove material.
Transportation: Waves and tides move eroded material along the coast (e.g., longshore drift).
Deposition: When waves lose energy, they deposit the transported material, forming beaches and other coastal features.
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What are the two types of sub-aerial processes?
Subaerial Processes:
These processes occur on land and involve the breakdown and movement of rocks and soil. They include:
Weathering: The breakdown of rocks due to atmospheric conditions, like freeze-thaw cycles or chemical reactions.
Mass Movement: Gravity causes land to move downslope, leading to landslides or rockfalls.
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How many sediment cells in England and Wales?
11
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