1
Q
Describe the coastline of Western and Northern Britain.
A
- A resistant rock coastline
- Igneous granite, Basalt
-These can withstand frequent storms with little erosion - There is also compacted older sedimentary rock and metamorphic rock
2
Q
What are the features of high energy coastlines?
A
- Rocky coasts are found here
- Stretches of the Atlantic facing coast e.g. Cornwall
- Rate of erosion exceeds the rate of deposition
- Landforms include; headlands, cliffs and wave cut platforms
3
Q
Describe the coastline of Eastern and Southern Britain.
A
- Younger, weaker sedimentary rocks
-Chalks, clays and sandstone - Most of Eastern England is low lying sandy beaches, and coastal plains, and has habitats such as salt marshes, lagoons and mud flats
-e.g the wash which is a coastal plain formed by 4 rivers: Ouse, Nene, Welland and Witham
4
Q
What are the features of low energy coastlines?
A
- Sandy and estuarine coasts
- Waves are less powerful, or where the coast is sheltered from large waves
- Where the rate of deposition exceeds the rate of erosion
5
Q
Describe the inputs of a sediment cell.
A
- Marine (waves, tides and storm surges)
- Atmospheric (weather, solar energy, climate change
- Land (rock type, tectonic activity)
- People (human activity, coastal management)
6
Q
Describe the Processes of a sediment cell.
A
- Weathering
- Deposition
- Mass movement
- Erosion
- Transport
7
Q
Describe the outputs of a sediment cell.
A
- Erosional landforms
- Depositional landforms
- Different types of coasts
8
Q
What is a sediment cell?
A
- Sediment supply is sourced by weathering and erosion
- This is then transported and deposited to produce coastal landforms
- Sediment cells are dynamic, so any change to a component will have an impact on the rest of the system
9
Q
What are some ways you can classify coasts?
A
- Geology - rocky, sandy, concordant, discordant and estuarine coasts
- Level of energy - high/low
- Balance between erosion and deposition - and their features
- Changes in sea level - creating emergent or submergent coasts
10
Q
What is the foreshore?
A
- Area lying between the high water mark and the low water mark
-Seen as most important for marine activity
11
Q
What is the backshore?
A
- Area between the high water mark and the landward limit of marine activity
-closest to the land
12
Q
What is the littoral zone?
A
- The area between the land and the sea - stretches into the sea and on the shore
- It is constantly changing because of dynamic interaction between processes
13
Q
What is the inshore?
A
- Area between the low water mark and the point where the waves cease to have influence on the land around them
14
Q
What is the fetch?
A
- Distance of open water over which the wind can blow
15
Q
What is the offshore?
A
- Area beyond point where waves cease to impact the seabed
-activity limited to depostion fo sediments
16
Q
What causes waves?
A
- The stronger the wind is, the longer it blows for, and the longer the fetch
- The larger the wave will be, and the more enrgy it will have
- Frictional drag increases as wind speed increases, making the wave bigger
Waves are a medium through which energy is transferred
17
Q
What is a beach?
A
- A deposit of sand or shingle at the coast
18
Q
What is the crest?
A
- The top of a wave
19
Q
What is the trough?
A
- The lowest point of a wave
20
Q
What is the swash?
A
- The forward movement of a wave up the beach
21
Q
What is the backwash?
A
- The backward movement of water down a beach when a wave has broken
22
Q
What is wave frequency?
A
- Number of wave crests passing one point each second
23
Q
What is the wave orbit?
A
- The shape of the wave - varying between circular and eliptical
- The orbit diameter decreases with depth, to a depth roughly equal to the wavelength
- There is no further movement related to wind energy
-This is the wave base
24
Q
What is a wave period?
What is the wavelength?
A
- Time required for the wave crest at one point to reach a point a wavelength away
The middle of one crest to the middle of the next crest
25
Why do waves break?
* In water, there is little horizontal movement of ocean water
* As the water reaches the coastline, it has increased contact with the shelving sea bed - exerts frictional force on the base of the wave (circular orbit changed to an eliptical orbit)
* As the wave gets closer, the friction grows, so the top of the wave moves faster than the bottom
* Eventually, the crest curves over and creates a breaking wave
26
What are the features of a constructive wave?
* Short amplitude
* Long wavelength
* Low frequency (6-8 waves per min)
* Strong SWASH, weak BACKWASH
* Beach profile with a gently shelving sea floor
27
Whatare the features of a destructive wave?
* High amplitude
* Short wavelength
* High frequency (10-14 waves per min)
* Weak SWASH, strong BACKWASH
* Beach profile with a steeply shelving coastline (storm beach)
28
What is the amplitude?
* Half the wave height
* From the still line to a crest
29
What landforms are created in a wave dominated environment?
* Wave-cut platform
* Cliffs
* Beaches
* Spits
* Deltas
30
What landforms are created in a tide dominated environment?
* Mudflats
* Sand flats
* Salt marshes
* Deltas
31
What landform is created in awind dominated environment?
* Sand dunes
32
How is a waves energy impacted by the coastline?
* Coastlines are not uniform, so the depth of water around a coast varies
* Waves are refracted, so energy is concentrated around headlands, but reduced around bays (headlands shelter them)
* Wave energy decreases as water depth decreases
* Refraction is not always fully achieved resulting in logshore drift
33
What is coastal morphology?
* The shape and struture of coastal landscapes, and their features
34
How is the morphology of a coastline determined?
* Lithology - physical characteristics of the rock
* Relief and slope - cliff profiles
* Rock type
* Permeability
35
What makes up the lithology of a coastline?
* Strata
* Bedding planes
* Joints
* Folds
* Faults
* Dips
36
What are strata?
* Layers of rock
37
What are bedding planes?
* Natural breaks in the strata
* Caused by gaps in time during periods of rock formation
| Horizontal cracks
38
What are joints?
* Fractures in the rock
* Caused by contraction of sediments as they dry out, or by earth movement during tectonic uplift
| Vertical cracks
39
What are folds?
* Formed by pressure during tectonic activity which makes rocks buckle and crumple
40
What are faults?
* Formed when the stress/pressure a rock is subjected to exceeds its internal strength
-The fault then slips or moves along the fault plane
41
What are dips?
* The angle rock strata lie at
-It can be a seaward or landward dip
-Cliffs with a seaward dip have a gentler coastline
42
What factors determine a cliff profile?
* Relief is affected by geology
* Relationship between rock type, lithology and rock profiles
* Cliff profiles are subject to marine processes, and sub aerial processes
43
What are some types of chemical weathering?
* Carbonation
-CO2 dissolves in rainwater, forming carbonic acid
-this reacts with the calcium carbonate in limestone, chalk, marble
* Oxidation
-Rocks with metallic elements react with oxygen in air/water and 'rust'
* Hydrolysis
-Combination of water (as a weak acid), reacting with minerals in the rock
44
What are some types of mechanical/physical weathering?
| Physical - Fracture and break down of rocks into fragments
* Freeze-thaw weathering
-Water expands when it freezes
* Salt crystals
-Salt water goes into cracks, and the water evaporates so salt is left behind
-This builds up and applies pressure to the crack
* Wetting and drying
-Water contracts when it is dry, so causes cracks
45
What are some types of biological weathering?
| A form of physical weathering
* Growing plants
-Roots can widen cracks
* Burrowing animals
46
How does geology influence the morphology of a coastline?
* Rocky type can influence permeability
-Affects the rate at which it is eroded, and the features formed
47
What is igneous rock?
* Rocks which have a crystalline structure
* They are resistant and impermeable
* Formed when magma cools
| e.g. granite, basalt, diorite
48
What is sedimentary rock?
* Are formed from the accumulation of sediments of other rocks by deposition - these can be lithified
* Jointed sedimentary rocks are permeable - e.g. sandstone and limestone
* Other sedimentary rocks have air spaces between their particles making them porous - e.g. chalk
49
What are metamorphic rocks?
* Existing rocks undergo conditions with extreme temperatures, and pressure
| e.g. schist, slate, marble
50
What are some erosion rates for different types of rocks?
* Glacial till - 1-10m/yr
* Sandstone - 1cm-1m/yr
* Limestone - 1mm-1cm/yr
* Granite - 1mm/yr
51
What factors affect the rate of coastal recession?
* Wave type/energy
* Weathering
* Human activity
* Mass movement
* Geology
* Morphology
52
What is a concordant coastline?
* Rock type runs parallel to the shoreline (in line with)
* Often produces straighter coastlines
53
What is a discordant coastline?
* Rock type runs perpendicular to the sea
* Often produces headlands and bays
54
What is hydraulic action?
* The force of water against the coast
* The waves enter the cracks (faults) in the coastline, and compress the air within
* When the wave retreats, the air in the crack expands, causing a minor explosion
55
What is solution?
* The chemical action of sea water
* The acids in the salt water dissolve rocks on the coast - limestone and chalk are particularly prone to this process
56
What is abrasion?
* The coast is worn down by material carried in the waves
* Waves through these particles against the rock, sometimes at a high velocity
57
What are sub-aerial processes?
* Include weathering and mass movement
* Operate on the cliff face to weaken it and provide material for coastal erosion
58
What is attrition?
* Materials carried by the waves bump into eachother, and so are smoothed and broken down into smaller particles
59
What is differential erosion?
* The altering rate of erosion on soft and hard rock
60
How is a wave-cut platform formed?
* Destructive waves hit the rock face between the high and low water mark
* Waves undercut the rockface forming a wave-cut notch - rock overhangs this notch
* After constant attack by destructive waves, the overhanging rock collapses, forming a wave-cut platform
61
How are caves formed?
* Cracks at the base of the headland become exposed thorugh hydraulic action - they are widened
* Cracks widen further by weathering processes
* Wave refractionmeans destructive waves concentrate their energy on the sides - deepens cave
62
How are arches formed?
* If 2 caves are aligned, waves may cut through the rock in the middle to form an arch
63
How are stacks formed?
* The arch becomes unstable and collapses under its own weight
* This is aided by marine erosion and sub-aerial processes (weathering)
64
How is a stump formed?
* The stack is eroded at its base, creating new wave-cut notches
* Sub-aerial processes continue to weaken the stack from above
* The stack eventually collapses
65
What is longshore drift?
* The process of material being transported along the coastline
66
How does longshore drift work?
* Waves (that carry sediment) approach the coast at an angle - because of prevailing winds, and the gravitational pull of the moon
* This is SWASH
* BACKWASH is the motion of receding waves (carrying sediment) - this always happens at a right angle
67
What is lateral shift?
* The net effect of movement up and down the beach
68
What is suspension?
* Fine particles of silt that hang in the water to be transported
69
What is solution - transportation?
* Minerals dissolve in the water to be transported
70
What is saltation?
* Stones and pebbles bounce along the bed
71
What are tides?
* Tides change the water levels
* Caused by the gravitational forces exerted on the earth by the moon
72
What is traction?
* Rocks and boulders are rolled along the bed by the force of the water
73
What does a high tide mean?
* It will lead to strong tidal currents as the tides rise and fall
* They are usually strong near estuaries and are key in transporting sediment
74
What is tidal range?
* The difference in height between high and low tides
75
What is terminal groyne syndrome?
* The consequence of groynes starving the beach down the coast while building it at another point
76
What is a spit?
| Give an example
* A sand or shingle beach ridge, extending beyond a turn in the coastline (usually greater than 30^o)
| Spurn head, Holderness
77
How is a spit formed?
* At the turn, longshore drift current spreads out and loses energy - leading to deposition
* The length of a spit is determined by the existence of secondary currents causing erosion - either the flow of a river, or wave action
78
How do bay head beaches form?
| Give an example
* A swash feature
* Waves break at 90^o to the shoreline and move sediment into a bay where a beach forms
* Due to wave refraction, erosion is concentrated at headlands, and the bay is an area of depostion
| Lulworth cove, dorset
79
What is a tombolo?
| Give an example
* A sand or shingle bar that attaches the coastline to an offshore island
| St Ninians tombolo, Shetland
Chesil beach, Dorset
80
How are tombolos formed?
* Due to wave refraction around an offshore island that creates an area of calm water and deposition between the island and the coast
81
What is a barrier beach/bar?
| Give an example
* A sand or shingle beach connecting two areas of land with a shallow water lagoon behind
| Chesil beach, Dorset
82
How is a barrier beach/bar formed?
* A spit grows so long that it extends across a bay, closing it off
83
What is a cuspate foreland?
| Give an example
* Triangular shaped feature extending out from the shoreline
| Dungeness, Kent
84
What is a cliff, and how can it be formed?
* Vertical or sloping wall of rock
* Result from a number of processes:
-Geological, sub-aerial, marine, human activity
85
How is a cuspate foreland formed?
* There is debate about their formation
-Could be from the growth of two spits from opposing longshore drift directions
86
How can dips be formed?
* Tectonic forces can tilt and deform layers of rock so they dip at an angle
87
What is produced by a seaward dip?
* Gentle cliffs
* They are less stable, because loose material can slide down the bedding planes by mass movement
88
What do landward dipping beds produce?
* Steeper cliffs, but they are more stable
89
What does a vertical dipping bed produce?
* Steep cliffs
90
What does impermeable rock overlaying permeable rock mean?
* Percolation is limited, and the cliffs are more stable
* Mass movement is prevented
| Percolation=the slow movement of fluids through a porous structure
91
What does permeable rock overlaying impermeable rock mean?
* Water may soak into the cliff
* Slope failure is more likely as water builds up between the junction of the two rocks
92
How does latitude affect the coastline?
* Tropics: low wave energy and high rates of chemical weathering produce = low gradient cliffs
* In high latitudes there are low gradients, as the glacial processes produce large amounts of sediment
* Temperate regions have the steepest cliffs
-The removal of debris by high energy waves prevents material building up at the base
93
What are sand dunes made of and where are they found?
* Wind blown sand
* They are stabilised by plant succession
* On low energy coastlines e.g. Northumberland
94
What are halophytes and xerophytes?
* Halophyte: a plant that can survive in very salty conditions
* Xerophyte: a plant that can survive in conditions with little water
95
How can depositional features be stabilised?
1. Bare ground is colonised by pioneer species - these bind sand or mud with their roots, and add nutrients when they die/decay
2. Creeping plants with leaves keep moisture in the sand/mud
-These changes allow new species
3. Invaders provide shade and improve the soil
4. As the environment changes, new species colonise until it is stable
5. The final colonisers are trees, in the climax community
96
What is an embryo dune?
* Closest to the sea, and the smallest
* Contain very few species (pioneer species) -e.g. couch grass
97
What is a mobile dune?
* Yellow dunes
* Larger dunes
* Contain marram grass
* Come after embryo dunes
98
What is a semi fixed dune?
* Grey dune
* Have other plants beside marram grass
* Come after yellow dunes
99
What is a fixed dune?
* Come after semi-fixed dunes
* Have almost complete vegetation cover
100
What are dune slacks?
* Areas which develop where the sand becomes eroded, so that the water table is reached
* The sand forms a damp depression, and the area is prone to flooding
* After fixed dunes
101
What is the climax?
* Sand dunes that have developed into scrub or woodland
* Are the oldest and last type of dune
102
What is a salt marsh, and where can they be found?
* Areas of flat silty sediments
* Accumulate around estuaries or lagoons
* Develop in:
-sheltered areas where deposition occurs
-where salt and freshwater meets
-Where there are no strong tides or currents to prevent deposition
103
How do plants help maintain depositional landforms?
* They dissipate wind energy - this leads to more depostion and less erosion
* When plants die and decompose they give organic matter which can:
-Help retain moisture and water
-Add nutrients so other species can colonise
* Their roots can bind and hold sediment, and help retain moisture
104
How do salt marshes form?
* As mud flats develop, halophytes e.g. eel grass begin to colonise and stabilise them
* Halophytes e.g. cordgrass help slow down tidl flow and trap more mud and silt
* As sediment accumulates, the surface becomes drier and different plants colonise e.g. sea asters
* Creeks divide up the marshes
105
What is solifluction?
* Occurs in areas of permafrost - the top layer of soil thaws in the warmer summer, but the layer below stays frozen.
* The surface layer becomes saturated as frost melts and flows over the subsoil and rock below
* Movement is 5cm to 1m per year
106
What is earth/mudflow?
- Heavy rain causes a reduction in friction and the earth turns into mud and flows slowly over the bedrock
107
What is soil creep?
* Individual particles of soil moving downhill
* It is the slowest form of mass movement, but it is almost continuous
108
What is rock slide?
- Rocks that are jointed or have bedding planes parallel to the slope are susceptible to landslides
- Increase in water can reduce friction and make this easier
- The underlying rock which slabs slide over is called the slip plane
109
What is rock fall?
- Occurs when mechanical weathering breaks large chunks of the cliff away
- The cliff has to be at an angle of 40 degrees or more
- Material that breaks off is called scree
110
What is the difference between sliding and slumping?
- Slumping is a rotational movement
111
What type of mass movement occurred?
| Holbeck hall case study
- Slumping, as there was rotational movement and the cliff was saturated
- This led to a mud/debris flow
| In Holderness in North Yorkshire, under a large cliff
112
When do slumps occur?
- In saturated conditions
- On moderate to steep slopes
- When clays or sand are overlying more resistant or impermeable rock like limestone or granite
- Terraced cliffs can be formed if it is repeated
113
What were the antecedent conditions?
| Holbeck hall case study
* There was 140mm of rain in the two months before the slide happened
* There were issues with the drainage of the slope which led to a water pressure build up
114
What is emergence?
- The impact of a fall in sea level - marine regression
115
What is a eustatic change?
- Global scale sea level change caused by a change in the volume of water in the ocean
116
What is an isostatic change?
- Local scale sea level change caused by a change in the level of the land relative to the level of the sea
117
What is the rock type here?
| Holbeck hall case study
* The cliff is made up of permeable rocks - glacial till (sandy and silty clay) - such as sandstone
118
What is submergence?
- The impact of a rise in sea level - marine transgression
119
What are three examples of isostatic changes?
- Tectonic uplift
- Glacial compression/decompression
- Sediment accumulation
120
What are three examples of eustatic changes?
- Sea floor spreading
- Climate change
- Glaciers
121
What is tectonic uplift?
- The movement of tectonic plates
- For example, when mountains are forming, the plates are being pushed upwards - as the land rises, it seems as though the sea levels are falling
122
What is sediment accumulation?
* The weight of the sediment load causes the land to subside, making it seem as though sea levels have risen
123
What is glacial compression/decompression?
* The weight of land ice (glaciers) pushes the land downwards - isostatic subsidence - making it seem as though sea levels have risen
* When the ice melts, there is no longer the weight of the glaciers on the land, so it starts to lift again - isostatic recovery/rebound - making it seem as thoigh sea levels have fallen
124
How does climate change lead to a eustatic change?
- Climate change and global warming mean that the temperature of the water increases
- As the temp increases, the particles gain more kinetic energy, and therefore expand causing sea levels to rise
- Thermal expansion
- An increase in global temps, also means more land base ice melts
125
How does sea floor spreading cause a change in sea level?
* As new rock is formed, the size of the basin increases, making it seem as though the volume of water has decreased
* Sea floor spreading relates to continental drift - if two continents collide, there is also an increase in the size of the basin as there is a reduction of area of continental crust
126
How do glaciers create eustatic changes?
- During glacial periods, more of the earths water is stored on land, so the volume of water in the sea decreases
- During interglacial periods, the glaciers melt so there is an increased volume of water in the sea, so sea levels rise
127
What is evidence that glaciers melting causes sea level changes?
* If the two main ice caps (Greenland and Antarctica melted), then the oceans would rise by 66 metres
128
What is some evidence for thermal expansion?
- From 1880 to 2012 , average global temperatures rose by 0.85C - in this time, sea levels rose by 21cm
- In the future, thermal expansion will play the most significant role in causing sea levels to rise
129
What is some general evidence that sea levels have changed?
- Scientists estimate that by 2100, average sea levels will rise between 30cm and 1m
- 1993-2010, sea levels rose by an average of 3.2mm, but they are rising much faster now
130
When was the last ice age?
- 18,000 years ago
- Ice covered about 30% of the land in the world
- In Britain, ice was up to 3km thick
131
What impact did the last ice age have on sea levels?
- Then, the sea level was at least 120m lower than it is today (lots of water was stored as ice)
132
Where can isostatic changes be seen?
* Since the last ice age, Scotland has been rising due to isostatic rebound
* Due to this, there is isostatic subsidence in the south of England
133
What is a ria?
- A submerged river valley
- e.g. Kingsbridge, Devon
- They are part of the lower course, where flood plains may be completely drowned
134
Describe what a ria looks like.
- Plan view - winding profile
- Cross section - quite shallow, becoming increasingly deep towards the middle (where the original river channel is)
- Long profile - quite even, with water at a fairly uniform depth
135
What is a fjord?
- A submerged glacial valley
- e.g. Lisefjord, Norway
- Very steep sides, and the water is very deep
136
Describe what a fjord looks like.
- Plan view - Straight profile, the glacier has cut off any interlocking spurs
- Cross section - steep valley sides (V-shaped), water is uniformally deep
- Long profile - have a shallower section at the seaward end
137
What is a raised beach?
| An emergent landform
- Areas of former wave cut platforms, and their beachesleft at a higher level than present sea level due to changes
- Found at a distance inland from the present coastline
- e.g. Little Gruinard, in NW Scotland
138
Why is the Maldives at risk to sea level rises?
| Where is the maldives?
- The highest point in the country is 2.3m above sea level
- A rise of 50cm by 2100 would mean the Maldives losing 77% of its land area
- Areas above sea level would become vulnerable to storm surges and erosion
- It has a population of 400,000 spread across 1200 islands
| The indian ocean
139
What is an example of tectonic uplift?
- Turakirae head, New Zealand
- Tectonic uplift from a major earthquake
140
What is an abandoned cliff line?
| An emergent landform
- Cliffs with wave cut notches, caves, arches and stacks (behind the raised beach) - due to marine erosion when sea levels were higher
141
What are the environmental impacts of sea level rise?
| Kiribati case study - the most at risk island to sea level rise
* 200m of marine transgression (land has dissapeared on one of the islands)
* Pollution, waste disposal and poor sanitation (lots of waste is brought by tides)
* King tides (extreme high tides) used to be non-existent
*
142
What are the social impacts of sea level rise?
| Kiribati case study - the most at risk island to sea level rise
* People are losing their homes and farmland
* Strain on water infrastructure
* Many have had to relocate - mass migration causes overcrowding and other problems
* Loss of tradition, culture and a connection with homeland
143
What is Kiribati doing to manage this?
| Kiribati case study - the most at risk island to sea level rise
- Building concrete and stone sea walls
- Planting mangroves (affordable and effective)
- Reduced tuna fishing to cut carbon emissions
- Migration with dignity - people sent for job training in Australia
144
How much have sea levels risen by?
| Kiribati case study - the most at risk island to sea level rise
* By 2050, the islands will see an additional 6-12 inches of water
* Since 1993, sea levels have risen at an average of 3.2mm per year
145
What are the economic impacts of sea level rise?
| Kiribati case study - the most at risk island to sea level rise
- Reduced tuna fishing, so money is no longer made from this
146
What is a dalmation coastline?
| Give an example.
* A submergent landform
* Made up of offshore islands and coastal inlets running parallel to the coastline
-The offshore islands are often long and narrow, seperated from the coast by narrow sea channels
| Dalmatia in croatia
147
How are dalmation coastlines formed?
* They are produced on a concordant coastline
* Valleys are created on the coastline that are parallel to the sea, so when the sea level rises, there are parts of the land that remain above the water (new islands are created)
148
What is a haff coastline?
| Give an example.
* An emergent landform
* Long ridges of sediment with sand dunes on top
* There are lagoons created between the ridges and the shore
-A lagoon is a haff, it is formed between the land and the bar formed from material deposition
| Along the southern Baltic coastline
149
How are haff coastlines formed?
* Stretches of the coastline have been exposed by decreasing sea levels, or isostatic rebound
* They are features of a low energy coastline - sediment is deposited by constructive waves
150
What is the Purbeck coast also known as?
| Purbeck coast case study
- The jurassic coast
151
What landforms can be found along the coast?
| Purbeck coast case study
- Headlands and bays
- Coves
- Arches, stacks and stumps
152
What rock types are found on the coast (order from newest to oldest)?
| Purbeck coast case study
- Chalk limestone - 97
- Greensand (sandstone) - 125
- Wealden beds (sandstone clay) - 140
- Purbeck beds (limestone mud) - 147
- Portland stone (limestone) - 150
| Number in millions of years
153
What rock type is found at swanage bay?
| Purbeck coast case study
* Has some unconsolidated wealden clay
* This can be easily eroded
* On a discordant coastline, so a bay is formed
154
How was durlston head formed?
| Purbeck coast case study
* Portland and purbeck limestone
* On a discordant coastline
* Steep cliffs have been created, as well as peveril point
-The limestone is jointed (created lines of weakness) that can be more easily eroded in places
155
How was stair hole created?
| Purbeck coast case study
- The sea eroded through the limestone and clays to create a small cove
- The lulworth crumple (limestone folding) can be seen here
156
How was warbarrow bay created?
| Purbeck coast case study
- Less resistant clay was eroded by the sea to expose the layers of chalk behind - now form the cliffs of the bay
157
How was lulworth cove created?
| Purbeck coast case study
- The sea gradually eroded the resistant limestone at the entrance
- Then there was rapid erosion of the less-resistant clays behind, so a cove was formed
158
How was durdle door created?
| Purbeck coast case study
- The sea eroded the harder limestone, and then the softer stone after
159
What landforms can be found here?
| Holderness coast case study
* Arch, stack
* Wave cut platform
* Spit
160
What is the geology of the coast?
| Holderness coast case study
- Consists of chalk and boulder clay
- Formed from glacial till (unconsolidated material)
161
How does the geology affect the coastline?
| Holderness coast case study
- It is very rapidly eroding
- At an average rate of 1.8m per year
- The rock can be easily saturated, causing slides and slumping
- At the foot, fine clay is removed by waves, so there is little left to form beaches and protect the cliffs from winter storms and high tides
162
What are the waves like here?
| Holderness coast case study
- The dominant waves are from the NE direction (largest fetch)
- There are mainly destructive waves
- Longshore drift carries material eroded south
163
How does the weather here affect the coast?
| Holderness coast case study
- Winter storms produce stronger waves and higher sea levels
- Rain saturates the rock more
164
How is spurn head (the spit) created?
| Holderness coast case study
- Sediments are brought here by longshore drift
- The low energy environement next to the estuary allows the spit to form
165
What has the humber estuary done?
| Holderness coast case study
- It has helped the wind, tides and river processes to develop dunes, mudflats and salt marshes (behind the spit)
166
How was flamborough head created?
| Holderness coast case study
- The rock here is resistant chalk, and forms a headland
- Horizontal bedding planes assist in the development of wave cut platforms
167
What are the human factors affecting the coast?
| Holderness coast case study
* Increased urbanisation can speed up/cause slumping
* Interfering with natural process e.g. terminal groyne syndrome starves beaches down the coast of sediment, making them more prone to erosion
-Groynes at Hornsea and Mappleton, starve Great cowden of sediment
* Global warming leads to sea level rise and more storms
168
What is dissipation?
The reduction of something
-e.g. wave energy
168
What is dredging?
The removal of sediment from the sea/river bed
169
What is terminal groyne syndrome?
* The increased erosion of a coastline due to sediment being trapped further along the coast
* Means no talus/scree to protect against waves
170
What are short-term influences on erosion rates?
* Human
-Agriculture
-Dredging
* Physical
-Weather
170
What is the difference between players and stakeholders?
Players = people that make decisions
Stakeholders = people affected by the decisions
171
What are more long-term influences on erosion rates?
* Human
-Urbanisation/development (more pressure, worse drainage systems)
-Coastal management (e.g. terminal groyne syndrome)
* Physical
-Geology
171
What are the economic and social impacts of erosion on the Holderness coast?
* Outmigration
* More spending on coastal defences
* Less tourism (e.g. due to fear of rockfalls like at holbeck)
* Farmland lost/bussinesses lost (means people can't relocate - value of their assets has been lost)
* Houses lost
* Loss of jobs
* Livlihoods lost
172
What is a conflict matrix?
Way to measure the potential/likely agreement or disagreement between different players and stakeholders in an area
173
What are the human causes of coastal recession around the nile delta?
* The ASH can trap sediment behind the dam wall (this starves the coast of a sediment source)
* High population density of 39mil (45% of Egypts population)
-Alexandria the largest city on the Delta has 4.5mil
* Area of intense farming, tourism&resorts, ports and infrastsurcture
-Urbanisation can disrupt natural processes
| ASH = aswan high dam
173
What are the physical causes of coastal recession around the nile delta?
* Rising sea levels (due to global warming)
* Protective offshore bars being eroded
174
How has the ASH increased coastal recession?
| ASH = aswan high dam
* The construction of the ASH in 1964 reduced the sediment volume from about 130mil tons to 15mil tons
* Erosion rates increased from about 20m to 200m per yeardue to lack of sediment
| It is 1100km away from the nile delta (where the nile meets the sea)
175
What are the envrionmental effects of coastal recession?
| Nile delta case study
* ASH has limited the seasonal flooding that would deposit rich, fertile sediments on the river banks
* Rising sea levels increase the salinity of the water, decreasing the fertility of the land
* Ecosystem is affected
| ASH = aswan high dam
176
What are the social effects of coastal recession?
| Nile delta case study
* Farmers cannot afford the steps that need to be taken to keep their land fertile
* Many people (especially those in poverty) will be displaced (probably millions)
176
What can be done to manage coastal recession?
| Nile delta case study
* More coastal defences added
-Sea walls
-Rip-rap
-Revetments
* Trap less sediment at the dam
* Reduce emissions (to reduce global warming, and rising sea levels)
177
What is adaptation?
-'Learning to live with something' and --Evolving to deal with changed conditions
177
What are storm surges?
* Sudden and short term change/rise in sea levels
* Caused by intense low pressure systems from depressions and tropical storms
* Can get up to 10m tall
177
What is mitigation?
-Trying to stop something
-'Avoiding the risk'
178
What is ICZM?
* Intergrated coastal zone management
* Hollistic, and looks at the whole coast
178
What is an estuarine coastline?
An environment where the river meets the sea
179
How are storm surges formed?
* Low pressure (rising air)
* Some water is lifted in the area of low pressure
* Winds push that water in the direction of the coast
* A funnel shaped coast (narrowing) can amplify the size of a surge
180
What are the impacts of storm surges?
* Erode beaches and coastal infrastructure
* Rivers and lakes may be affected
-e.g. If water moves up the river from the mouth (from a storm surge), a flood can occurr
181
How can we prepare for storm surges?
* Forecasters can monitor a hurricane, and predict where a storm surge will hit, and its height
* Use sea walls
* Evacuation
182
Why are Bangladesh's estuarine islands sinking so much?
| How much are they sinking by?
* Isostatic readjustment
* Clearance forests and drainage of more than 50 islands in the Ganges-Brahamputra river delta (some areas now used to grow rice instead)
* Human actions have prevented the natural deposition of sediment that used to maintain the islands height
| As much as 1.5m in the last 50 years
183
How did Bangladesh try and deal with flooding?
* Large earth embankments were built in the 60/70s
-400km of embankments built in the last 50 years
184
What is the population like in Bangladesh?
* Worlds mostdensely populated country (169mil in 2015)
* 46% of the pop lives on land <10m below sea level
184
What are the risks to people living on sinking islands in Bangladesh?
* Increased risk of flooding if the embankments give way
-About 30million live on land surrounded by embankments
184
What are physical factors causing increased flood risk in Bangladesh?
* Bangladesh lies on the floodplains of 3 major rivers (Ganges, Brahmaptura, Meghna)
* Himalayan snow melt
* Monsoon rain
* Violent thunderstorms in March & May (can bring up to 6m waves)
185
What are human factors causing increased flood risk in Bangladesh?
* Deforestation causes soil erosion - reduces the ability of the land to absorb water
* Irigation: causes river channels to silt up, reducing their capacity to hold flood waters
* Global warming increases rainfall, and the speed Himalayan snow melts
185
How can mangroves be used as flood managment?
* Stabilise coastlines against erosion
* Provide shelter against extreme weather events
-absorb and disperse tidal surges
* Also provide a nursery for coastal fish
186
How did mangroves protect sri lanka during the 2004 boxing day tsunami?
* 2 people died in the settlement protected by dense mangrove and scrub forest - 6000 died where protective vegetation was removed
* They are the first nation to protect all of its mangrove forests
187
What are some pros and cons of mangroves?
| non-flood related reasons
* Store huge amounts of carbon
* Make access to the sea difficult - this could have economic impacts (tourism reasons)
188
What were the characteristics of cyclone sidr?
* 15 Nov 2007
* Storm surges of 6m
* 223km/hr winds
* Heavy rain
* Category 4 storm
189
How was cyclone sidr prepared for/managed?
* Mangroves as management in some areas
* Improved forecasting
* Embankments (these failed)
* Little coastal management in the area
189
What were the social impacts of cyclone sidr in Bangladesh?
* Drinking water contaminated by debris, and wells flooded by saltwater
* Sanitation infrastructure destroyed (raising risk of disease)
* Roads and waterways impassable
* Lower than expected death toll - offshore islands had the highest no.
190
What were the economic impacts of cyclone sidr in Bangladesh?
* Total cost was US$1.7bil
* Electricity supplies and communications knocked out
* Damaged housing, roads and other infrastructure
191
What were the environmental impacts of cyclone sidr in Bangladesh?
* Storm surge breached coastal and river embankments - caused flooding of low lying areas
192
How was the NSSS in 2013 prepared for/managed?
| NSSS = north sea storm surge
* Netherlands:
-Delta works constructed (4.2b euros spent after bad storm surge in 1953)
* UK
-Flood defences that needed updating
-Properties were protected by the Environment agency's flood defences
193
How did the NSSS 2013 affect the Netherlands and the UK?
| NSSS = north sea storm surge
* Netherlands:
-Strong winds
-Storm surge up to 2m high
* UK:
-Widespread flooding on the East coast
193
What were the environmental impacts of the NSSS 2013 in the UK?
* London saw the highest tide since the Thames barrier was built in 1984
* 1700 hectares farmland flooded
* 64 severe flood warnings
193
What were the social impacts of the NSSS 2013 in the UK?
| NSSS = north sea storm surge
* 160,000 warnings to homes and businesses
* 800,000 properties protected by the Environment agency's flood defences
* 720 properties flooded
* 1700 hectares of farmland flooded
* 64 severe flood warnings
193
What were the economic impacts of the NSSS 2013 in the UK?
* Est. cost of £200million
* Government invested £270million in new and updating existing flood defences
193
Did the NSSS in 2013 affect any other countries?
| NSSS = north sea storm surge
* In Germany, storm surges reached up to 3.74m high
193
What is amenity value?
Characteristics of an area that contribute to the pleasentness/attractiveness of that area as a place to:
-live
-work
-visit
194
What are some environmental costs of coastal recession?
* Loss of coastal ecosystems and habitats
194
How easy is it to quantify different impacts of coastal recession?
| quantify = measure cost of
* Economic - easy
* Social - difficult
* Environmental - almost impossible
194
Where are environmental refugees likely to come from?
* Low lying islands:
-Maldives (Indian ocean)
-Kiribati (Pacific)
-Barbados (atlantic)
-Tuvalu (Highest point is 4.5m above sea level, most is 1.2m - in the pacific)
-Seyechelles (80% live and work on the coast)
194
What are the economic costs of coastal recession?
* Flooded farmland
* Buildings damaged
* Power outages
194
What do places like tuvalu, kiribati and the maldives tend to have in common?
* Many are fringed by coral reefs which act as a natural coastal defence against erosion - rising ocean temperatures leads to coral bleaching
* Small/narrow economies based on tourism and fishing - easily disrupted
* High population densities and limited space - no oppurtunity for relocation
* Water supply is limited (at risk from salt water as sea levels rise), and groundwater is overused
194
What are some social costs of coastal recession?
* Deaths
* People lose their jobs/businesses/livlihoods
* Costs of relocation
* Impact on health
195
What is sustainable coastal management?
* Long-term approach that considers future threats such as sea level rise and storm surges
195
What can sustainable coastal management involve?
* Monitoring change and adapting to unexpected trends
* Managing natural resources to ensure long term productivity
* Managing flood/erosion risk
* Relocating
* Creating alternative livlihoods, before others are lost
* Educating communties (how to adapt, why change is needed)
195
Why might local people not like sustainable coastal managment?
* It can involve abandoning a vulnerable coastline/low lying area (due to coastal/erosion risk)
* This may conflict with the wishes of local people who may lose their land/home/job/sense of community
* People may feel there is no social justice
196
What were the impacts of coastal management in Namibia?
* People more educated and ready for the problems
* Relocation of communities
* Investing in infrastructure
197
Was was the cost effectiveness of the coastal reallignment in essex 2002?
| Soft managment
* cost £645,000
* Largest coastal reallignment in essex
* Soil quality and land value were low, so it was not worth maintaining the embankments, or building them higher
197
What type of management was used in Namibia, and what was the cost effectiveness of this?
* Hard engineering
* Three actions taken: 2 of low/moderate cost, 1 of high cost
* >US$6.8mil
* Maintaining the scheme could develop costs for the future
198
What were the adaptations to sea level rise in essex?
* Additional mudflats and salt marshes absorb incoming higher seas and storm surges
-Reduces the volume of water travelling up the essex estuaries and creeks
198
What were the positive and negative impacts of the management?
| Essex
* Positives:
-Less risk of flooding settlements
-New habitats created for wildlife
Populations of fish and marine invertibrates encouraged
* Negatives:
-Oyster fisherman working here may lose work - sediments could choke and kill oysters, and water level changes could remove habitats
-Increased erosion and flooding of nearby site would change bird habitats (impacts tourism)
199
What does these acronyms mean: ICZM, SMP, EIA, CBA?
* ICZM - intergrated coastal zone management
* SMP - shoreline management plan
* EIA - environmental impact assessment
* CBA - cost benefit analysis
199
Where did the ICZM start and why is this significant?
* Concept started at the 1992 Rio Earth summit
* Now used globally for a starting point for coastal management strategies
200
What does the ICZM do?
* Considers the entire coastal zone - includes ecosystmes, sediment cell, littoral zone and human activity etc
* holistic so involves management across political boundaries
201
What are the characteristics of an ICZM?
* Must plan for the longterm
* Adaptive managment - plans/policies can be changed if threats change
* Try to work with natural processes, not against them
* All stakeholders will have a say in policy decisions
201
What does an EIA include the assessment of?
* Impacts on water movement and sediment flow
* Impact on water quality
* Possible changes to flora and fauna
* Wider environmental impacts e.g. air and noise pollution
201
What is an EIA?
Considers:
* Short term impact of any plans on the coastal environment
* Long term impacts of changing a policy
* It can be wide ranging
202
What can a CBA be used for?
* To help decide if defending a coastline from erosion and or flooding is justifiable
* Costs are forecasted and then compared with the expected benefits
* A project where costs exceed benefits is unlikely to go ahead
* Considers amenity value
203
What are other considerations in an ICZM?
* Economic development has to occurr to ensure quality of life is improved - this needs to benefit everyone, and be environmentally appropriate
* Must harmonise the policies, opinions and decisions of stakeholders
204
What are piecemeal coastal defences?
* When management is done in isolation
* Doesn't consider the impacts on other parts of the coast/sediment cell
205
What are littoral cells?
* Sediment cells that include erosion, transportation and deposition
* Mainly a closed a system
205
What are SMP's?
* INclude CBAs and EIAs
* Identify risks associated with coastal management
205
Who oversees management in the UK?
* The government and environment agency (DEFRA)
* The local council
206
What is no active intervention?
* When nothing is done
206
What is done in managed realignment?
* When coastal retreat is allowed to happen, and things at risk on the coast are relocted
206
What is done in hold the line?
* Nothing is relocated, but coastal defences are put in place
207
What is done in advance the line?
* When land is reclaimed from the sea
207
Who were the players/stakeholders in the management scheme in Happisburgh, Norfolk?
* Residents
* Caravan owners
* Farmers
* Coastal concern action group
* North Norfolk district council
* DEFRA
207
What factors are considered when deciding on an SMP?
* Political, social and economic reasons
* Engineering feasability
* Impacts on coastal processes
* Land use and value - cost effectiveness
* Environmental sensitivity
208
Who were the winners/losers in the management scheme in Happisburgh, Norfolk?
* Losers
-Home owners: House values are low, homes are constantly being lost - they may be able to relocate (costly)
-Farm/land owners
209
What were the positives of the management scheme in Happisburgh, Norfolk?
* £3mil from the gov to:
-create a buffer zone between cliff and main village
-relocate caravan park and local residents
-remove derelict defences
* Protects local tourist assets (caravans)
* Increases biodiversity
* Allows natural processes and evolution of the coastline
* Reduce coastal blight and improve confidence in the local community
* Allowing relocation of those with at risk property
210
What were the negatives the management scheme in Happisburgh, Norfolk?
* Increases coastal 'squeeze', leading to a loss of national and international intertidal habitats
* Increases loss of reed beds and habitats for geese species
* Government refused to protect here as not cost effective, and Happisburgh is not a priority
210
What did the management scheme in Happisburgh, Norfolk consist of?
* Managed retreat approach (SMP1)
* SMP2 chnanged from hold the line to managed realignment - allows for some defences in the future
-no sustainable short/long term coast defence due to coastal processes, sea level rise and national policy
* Temporary rock sea defence to control erosion rates for time for adaptation measures to be developed (5000 tons granite rip-rap £200,000)
* Removal of beach debris giving beach access
* Improving understanding of coastal heritage
* Demolition and replacement of properties most at risk
211
Who were the players/stakeholders in the management scheme in Chittagong, SE Bangladesh?
* Asian development bank
* International fund for agricultural development (UN agency)
* local residents
212
Who were the winners/losers in the management scheme in Chittagong, SE Bangladesh?
* Losers
-Residents
-Biodiversity
* Winners
-Biodiversity
212
What did the management scheme in Chittagong, SE Bangladesh consist of?
* Improving road connections
* Raising embankments to 60cm above normal flood levels, and making them resistant to erosion
* Training in climate resilience and adaptation measures
* Constructing, improving, or extending 25 tropical cyclone shelters - taking account of sea level rise and higher wind speeds
* Creating new market areas with sheds raised on platforms (above expected 2025 sea level)
212
What were the negatives of the management scheme in Chittagong, SE Bangladesh?
* Disturbance of people and natural habitats
-e.g. during construction - permanent removal of vegetation and relocation of some households
212
What were the positives of the management scheme in Chittagong, SE Bangladesh?
* Helping to alleviate poverty by:
-generating income oppurtunities
* Adapting to climate change
* Reducing disaster risk
* Environmental enhancement e.g. planting trees
