Coasts Flashcards
(240 cards)
1
Q
What is a high energy coastline?
Give a UK example
A
Stretches of the Atlantic-facing coast, where the waves are powerful for much of the year
Where the rate of erosion exceeds the rate of deposition.
Rocky coasts and erosional landforms tend to be found here.
UK - Cornwall or north-western Scotland.
2
Q
What are low energy coastlines?
Give a UK example
A
Stretches of the coast where the waves are less powerful or where the coast is sheltered from large waves
Where the rate of deposition exceeds the rate of erosion.
Sandy and estuarine coasts and landforms such as beaches, spits and coastal plains tend to be found here.
UK - Lincolshire and Northumberland.
3
Q
What type of coastline does Cornwall have?
A
Resistant rock coastline.
It is rocky and can withstand the frequent winter storms without suffering from rapid erosion.
4
Q
What type of rocks does the Cornwall coastline consist of?
A
Igneous rocks - e.g. basalt & granite
Older compacted sedimentary rocks - e.g. old red sandstone
Metamorphic rocks - e.g. slates and schists
5
Q
What is a coastal plain landscape?
Give a UK example
A
Areas of weaker and younger sedimentary rocks - e.g. chalks, clays, sand & sandstone.
UK - The Wash (the largest estuary system in the UK)
6
Q
What are the inputs of the coastal system?
A
Marine - waves, tides & storm surges
Atmospheric - weather/climate, climate change & solar energy
Land - rock type and structure & tectonic activity
People - human activity & coastal management
7
Q
What are the processes of the coastal system?
A
Weathering, mass movement, erosion, transport & deposition
8
Q
What are the outputs of the coastal system?
A
Erosional landforms, depositional landforms & different types of coasts.
9
Q
What is the littoral zone?
A
It stretches out into the sea and onto the shore.
Tides and storms affect a band around the coast.
It is constantly changing because of the dynamic interaction between the processes operating in the seas, oceans and on land.
10
Q
Why does the littoral zone vary?
A
Short-term factors - e.g. individual waves, daily tides & seasonal storms
Long-term factors - e.g. changes to sea levels or climate change
11
Q
What occurs in the backshore and foreshore?
A
The greatest human activity.
The physical processes of erosion, deposition, transport and mass movement.
12
Q
What processes effect sediment supply ?
How?
A
Weathering & erosion - produce output in the form of sediment.
Transportation and deposition - produce coastal landforms.
13
Q
What categories are used to classify coasts?
A
Geology, level of energy, balance between erosion and deposition & changes in sea level.
14
Q
What is the Lulworth Crumple?
A
Thin beds of Purbeck limestone and shale are clearly visible in the side of the cliff.
These layers of rock are folded in response to tectonic movements about 30 million years ago.
15
Q
What is coastal morphology?
A
The shape and form of coastal landscapes and their features.
16
Q
What is lithology?
A
The physical characteristics of particular rocks.
17
Q
Define strata
A
Layers of rock.
18
Q
Define bedding planes
A
Horizontal cracks.
Natural breaks in the strata, caused by gaps in time during periods of rock formation.
19
Q
Define joints
A
Vertical cracks.
These are fractures, caused either by contraction as sediments dry out or by earth movements during uplift.
20
Q
Define folds
Give an example
A
Formed by pressure during tectonic activity which makes rocks buckle and crumple.
e.g. Lulworth Crumple
21
Q
Define faults
A
Formed when the stress or pressure to which a rock is subjected, exceeds its internal strength (causing it to fracture).
The faults then slip or move along fault planes.
22
Q
Define dip
A
The angle at which rock strata lie (horizontally, vertically, dipping towards the sea or dipping inland).
23
Q
Define relief
A
Height and slope of land.
24
Q
What are the characteristics of igneous rocks?
Give an example
A
Crystalline, resistant & impermeable.
e.g. granite
25
What are the characteristics of (joined) sedimentary rocks?
Give an example
S - formed in strata
e.g. limestone, chalk, sandstone & shale
JS - permeable
e.g. sandstone & limestone
26
What are the characteristics of metamorphic rocks?
Give an example
Very hard, impermeable and resistant.
e.g. marble & schist
27
What is a concordant coast?
Give an example
Where bands of more resistant and less resistant rock runs parallel to the coast.
e.g. Isle of Purbeck
28
Describe the rock type on Dorset's coast
Varies between resistant Purbeck limestone (which forms steep cliffs) to less resistant clays and sands.
Alternate along the coast, so that where a resistant rock is eventually eroded - allowing the sea to break through to less resistant rock behind - erosion follows more quickly.
29
What are Dalmatian coasts?
Concordant coastline.
They have formed due to sea level rise.
Valleys and ridges run parallel to each other.
Where the valleys flooded, the tops of the ridges remained above the surface of the sea - as a series of offshore islands that run parallel to the coast.
30
What are Haff coasts?
Concordant features - long spits of sand and lagoons - aligned parallel to the coast.
31
Define discordant coast
Where the geology alternates between bands of more resistant and less resistant rock, which run at right angles to the coast.
32
How do headlands affect incoming waves?
They force incoming waves to refract or bend - concentrating their energy at the headlands.
This increases their erosive power leading to a steepening of the cliffs and their eventual erosion into arches and stacks.
33
How do bays affect incoming waves?
Their energy is dissipated and reduced.
This leads to the deposition of sediment - forming a beach.
34
What happens the water as a wave approaches the coast?
It becomes shallower and the circular orbit of the water particles changes to an elliptical shape.
35
True or False
Wavelength and velocity increase as the wave approaches the coast.
False
36
True or False
Wave height increases as it approaches the coast.
True
37
What causes a wave to break?
Force pushes the wave higher so that it become steeper before spilling.
38
Describe the characteristics of constructive waves
Low, surging waves - with a long wavelength.
Strong swash, weak backwash.
Beach gain.
39
Describe the characteristics of destructive waves
High, plunging waves - with a short wavelength.
Weak swash, strong backwash.
Beach loss.
40
Why does beach morphology change?
Beaches consist of loose material, so their morphology alters as waves change.
41
Why does beach profile change?
Seasonal changes in wave type create summer and winter profiles.
42
Explain summer beach profiles
Constructive waves are more common and they are less frequent so wave energy dissipates and deposits over a wide area.
The swash deposits larger material at the top of the beach - creating a berm.
The backwash becomes weaker - it only has enough energy to move smaller material so the beach material becomes smaller towards the shoreline.
43
Explain winter beach profiles
Destructive waves occur at a high frequency.
Berms are eroded by plunging waves and high energy swash.
Strong backwash transports sediment offshore.
The backwash exerts a current known as a rip or undertow - dragging sediment back as the next waves arrives over the top.
44
What are swell waves?
Originate in mid-ocean and maintain their energy for thousands of miles.
UK coast - they appear as larger generated waves.
45
What is fetch?
The distance of open water over which waves move.
46
True or False
The greater the fetch, the larger the wave
True
47
What are the 2 main types of waves?
Constructive & destructive
48
What is abrasion?
When waves advance, they pick up sand and pebbles from the seabed.
when they break at the base of the cliff, the transported material is hurled at the cliff foot - chipping away at the rock.
49
What is hydraulic action?
When a wave advances, air can be trapped and compressed.
When the wave retreats, the compressed air expands again.
Weakens joints and cracks in the cliff - causing pieces of rock to break off.
50
What is corrosion?
When cliffs are formed from alkaline rock or cement bonds the rock particles together, solution by weak acids n seawater can dissolve them.
51
What is attrition?
The gradual wearing down or rock particles by impact and abrasion, as the pieces of rock are moved by waves, tides and currents.
Reduces the particle size and makes stones rounder and smoother.
52
How does lithology influence erosion?
Any geological weaknesses are eroded more quickly.
Bands of more resistant rock between weaker joints and cracks erode more slowly .
53
What is differential erosion?
Selective erosion of areas of weakness - as opposed to more resistant areas and types of rock.
54
What are stacks and stumps?
Isolated pillars of rock that lie just off the coast and are surrounded by water.
Stumps - completely covered at high tide.
55
What are shoreline platforms?
Flat rocky platforms that extend out from the coast.
56
How are wave cut notches created?
When waves break against the foot of the cliff, erosion tends to be concentrated close to the high-tide line.
Creates a wave-cut notch, which begins to undercut the cliff.
57
How are shoreline platforms created?
As the wave-cut notch gets bigger, the rock above it becomes unstable and eventually the upper part of the cliff collapses.
As these erosional processes are repeated, the notch
migrates inland and the cliff retreats .
58
Where are the steepest cliffs found?
Where rock strata are vertical and horizontal or have almost vertical joints.
59
Where are the gentlest cliffs found?
Where rock dips towards or away from the sea.
60
How are caves formed?
Erosion exploits weaknesses in the cliff. When joints and faults are eroded by hydraulic action and abrasion, this can then create caves.
61
When are blowholes formed?
If the overlying rock collapses, a blowhole will develop as the cave opens up at ground level. During storm high tides, seawater can be blown out of these blowholes with considerable and spectacular force.
62
How are arches formed?
If two caves on either side of a headland join up, or a single cave is eroded through a headland, an arch is formed.
63
How are stacks formed?
The top of the arch will become unstable and collapse – leaving an isolated pillar of rock, called a stack.
64
How are stumps formed?
The stack itself continues to be eroded by the sea. As it collapses and is eroded further, it may only appear above the surface at low tide, and is now known as a stump.
65
Explain the process of longshore drift
As the waves advance, material is carried up the beach at an angle. The backwash then pulls material down the beach at right angles to the shore.
66
What is traction?
Relatively large and heavy rocks are rolled along the seabed.
67
What is saltation?
Smaller and lighter rocks 'bounce' along the seabed.
68
What is suspension?
Lighter sediment carried by the water.
69
What is solution?
Dissolved sediment carried in the water.
70
What are tides?
Changes in the water level of seas and oceans – caused by
the gravitational pull of the moon and, to a lesser extent, the sun.
UK coastline experiences 2 high and low tides a day.
71
What are spits?
Along narrow feature, made of sand or shingle, which extends from the land into the sea.
72
How are spits formed?
Sand or shingle is moved along the coast by longshore drift, but if the coastline suddenly changes direction, sediment
will begin to build up across the estuary mouth and a spit will start to form.
73
What are offshore bars?
Submerged ridges of sand or coarse sediment.
74
How are offshore bars formed?
Created by waves offshore from the coast.
Destructive waves erode sand from the beach with their strong backwash and deposit it offshore in bars.
75
What are barrier beaches?
Where a beach or spit extends across a bay to join two headlands.
76
What are barrier islands?
Where a beach becomes separated from the mainland.
77
What are tombolos?
A beach (or ridge of sand and shingle) that has formed
between a small island and the mainland.
78
How are tombolos formed?
Deposition occurs where waves lose their energy and the tombolo begins to build up.
79
What are cuspate forelands?
A triangular-shaped headland that extends out from the main coastline.
80
How are cuspate forelands formed?
It occurs where a coast is exposed to longshore drift from opposite directions. Sediment is deposited at the point where the two meet, which forms a natural triangular shape as it builds up.
81
What are pioneer species?
The first plants that colonise bare ground.
They begin the process of plant succession.
They modify the environment by binding sand or soil
with their roots and adding nutrients when they die and decay.
82
What is the purpose of creeping plants?
They help the sand or mud in dunes and salt marshes to retain moisture. They also modify the environment by providing shade as well as improving the soil.
83
What is the climatic climax community?
The final community adjusted to the climatic conditions of the area.
84
What are embryo dunes?
Embryo dunes are the first dunes to
develop. They grow into bigger fore dunes – which are initially yellow in colour, but darken to grey as decaying plants add humus.
85
Where to salt marshes develop?
In sheltered areas where deposition occurs.
Where salt and fresh water meet.
Where there are no strong tides or currents to prevent sediment deposition and accumulation.
86
What happens within sediment cells?
The sediment moves between the beach, cliffs and sea through the processes of erosion, transport and deposition. Any action taken in one place has an impact elsewhere in the cell.
Each cell operates between physical barriers that prevent the sediment from moving any further along the coast.
87
What are halophytes?
Salt-tolerant species - such as glasswort and
cordgrass - that help to slow down tidal flow and trap more mud and silt.
88
What is the sediment budget?
The amount of sediment available within a sediment
cell.
89
What is positive feedback?
If the sediment budget falls, waves continue to transport sediment (and erosion may therefore increase in some areas, because the sea has surplus energy).
90
What is negative feedback?
However if the sediment budget increases, more deposition is likely. The sea corrects itself, because it can only carry so much – and any surplus is deposited.
91
What is weathering?
Gradual breakdown of rock in situ or close to the surface. It creates sediment which the sea can then use to help erode the coast. Weathering also helps to increase the rate of erosion of some coasts.
92
What is mass movement?
The movement of weathered material down slope, as a result of gravity.
93
What is freeze-thaw weathering?
Water enters a crack or joint in the rock when it rains – and then freezes in cold weather. When water freezes, it expands in volume. This expansion exerts pressure on the rock, which forces the crack to widen. With repeated freezing and thawing, fragments of rock break away and collect at the
base of the cliff as scree.
94
What is salt weathering?
When salt water evaporates, it leaves salt crystals behind. These can grow over time and exert stresses in the rock, just as ice does – causing it to break up.
95
What is wetting and drying?
Frequent cycles of wetting and drying are common on the coast. Rocks rich in clay expand when they get wet and contract as they dry. This can cause them to crack and break up.
96
Explain how plant roots causes biological weathering
Thin plant roots start to grow into small cracks in a cliff face. These cracks then widen as the roots grow thicker, which breaks up the rock.
97
Explain how water causes biological weathering
Water running through decaying vegetation becomes acidic,
which leads to increased chemical weathering.
98
Explain how animals cause biological weathering
Birds and animals dig burrows into cliffs.
99
Explain how marine organisms cause biological weathering
Marine organisms are also capable of burrowing into rocks
or of secreting acids.
100
What is carbonisation?
Rainwater absorbs carbon dioxide from the air to form
a weak carbonic acid. This 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 – increasing the effectiveness of carbonation in winter.
101
What factors effect the type of mass movement?
The angle of the slope or cliff.
The rock type and its structure.
The vegetation cover.
How wet the ground is.
102
What is soil creep?
The slowest form of mass movement – and is an
almost continuous process.
It is a very slow downhill movement of individual soil particles.
103
What is solifluction?
Occurs mainly in tundra areas, where the ground is frozen.
When the top layer of soil thaws in the summer – but the
layer below remains frozen (as permafrost) – the surface layer becomes saturated and flows over the frozen subsoil and rock.
104
What are earth and mud flows?
An increase in the amount of water can reduce friction – causing earth and mud to flow over underlying bedrock. The
material becomes jumbled up.
105
What are rock falls?
Occurs when strong, jointed and steep rock faces/cliffs are exposed to mechanical weathering. The material, once broken away from the source, either bounces or falls vertically to form scree at the foot of the slope/cliff.
106
What are rock/debris slides?
Rocks that are jointed, or have bedding planes roughly parallel to the slope or cliff surface, are susceptible to landslides. An increase in the amount of water can reduce friction – causing sliding. Slabs of rock/blocks can slide over
underlying rocks along a slide or slip plane.
107
What are slumps?
Slumps often occur in saturated conditions. There is a
rotational movement. They occur on moderate to steep slopes. They are common where softer materials (clays or sands) overlie more-resistant or impermeable rock, such as limestone or granite. Slumping causes rotational scars. Repeated slumping creates a terraced cliff profile.
108
Where is Kiribati?
The nation of Kiribati consists of 33 widely spaced islands, which stretch across an area of the Pacific Ocean nearly
as wide as the USA.
109
How does global warming cause sea level rise?
Polar ice sheets (and glaciers) are melting, and because of thermal expansion.
110
What are the effects of sea level rise in Kiribati?
Contaminating its ground water sources and affecting its ability to grow crops.
Kiribati’s population will become environmental refugees.
111
What is eustatic change?
When the sea level itself rises or falls.
112
What is isostatic change?
When the land rises or falls, relative to the sea.
113
Explain eustatic change
In cold, glacial periods, precipitation falls as snow and forms huge ice sheets that store water normally held in the oceans. As a result, sea levels fall. At the end of glacial periods – as temperatures rise – the ice sheets begin to melt and retreat. Their stored water then flows into the rivers and the sea again – and sea levels rise.
114
Explain isostatic change
During glacial periods, the enormous weight of the
ice sheets makes the land sink. This is called isostatic subsidence. As the ice begins to melt at the end of a glacial period, the reduced weight of the ice causes the land to readjust and rise. This is called isostatic recovery.
115
What is happening to the land in the north and west of the UK?
It was covered by ice sheets during the last Ice Age – is still rising as a result of isostatic recovery.
116
What is happening to the land in the south and east of the UK?
Rivers pour water and sediment into the Thames estuary causing the crust to sink there and relative sea levels to rise.
Increased flood risks as a result of the land sinking due to isostatic change, as well as a rising sea level caused by global warming.
117
2 facts about the Boxing Day earthquake and tsunami
(magnitude, deaths)
Magnitude - between 9.0 and 9.3
Deaths - 300,000
118
How was Sumatra effected by the Boxing day earthquake and tsunami?
It worst hit because it was the closest land to the earthquake’s epicentre.
119
How was Banda Aceh effected by the Boxing day earthquake and tsunami?
Hit by 15-metre-high waves and flooded – just 15 minutes after the initial earthquake.
The earthquake caused the Earth’s crust at Banda Aceh to sink – permanently flooding some parts of the city.
120
What caused the Boxing day earthquake and tsunami?
1600 km of fault line slipping about 15 metres along the subduction zone where the Indian Plate slides under the Burma Plate. The seabed rose several metres – displacing an estimated 30 km³ of water and triggering the tsunami.
121
How can past tectonic activity have an impact on coasts?
The uplift of mountain ranges and coastal land at destructive
and collision plate margins
Local tilting of land causes it to be submerged or stranded above the current sea level.
122
What causes emergent coastlines?
Fall in sea level exposes land previously covered by the sea.
123
What causes submergent coastlines?
A rise in sea level flooding the coast.
124
What causes raised beaches?
As the land rose as a result of isostatic recovery, former shoreline platforms and their beaches were raised above the present sea level.
125
What are relic cliffs and where are they found?
Often the remains of eroded cliff lines can be found behind the raised beach, with wave-cut notches and caves as evidence of past marine erosion.
126
What causes rias and where are they found?
They form when valleys in a dissected upland area are flooded. They are common in south-west England, where sea levels rose after the last Ice Age – drowning the lower parts of many rivers and their tributaries to form rias.
127
What causes dalmation coasts?
Similar to rias but the rivers flow almost parallel to the coast – rather than at right angles to it.
128
What causes fjords and where are they found?
Formed when deep glacial troughs are flooded by a rise in sea level. They are long and steep-sided, with a U-shaped cross-section and hanging valleys. They are much deeper inland than they are at the coast. The shallower entrance marks where the glacier left the valley.
129
3 reasons why the Holderness coast is retreating rapidly?
Geology, fetch and longshore drift and beach material.
130
How does geology affect the Holderness coast?
Boulder clay is also known as glacial till, or drift, and is a mixture of fine clays, sands and boulders deposited by glaciers after the last Ice Age. Boulder clay is structurally weak, and has little resistance to erosion. It produces shallow, sloping cliffs between 5 and 20 metres high.
131
How does fetch affect the Holderness coast?
Holderness is exposed to winds and waves from the north-east, with a small fetch of about 500–800 km across the North Sea.
132
How do currents affect the Holderness coast?
They circulate around the UK from the Atlantic Ocean into the North Sea. The Atlantic’s fetch is 5000 km or more, so its currents add energy to the waves in the North Sea. There are often powerful destructive waves at work along this coastline.
133
How do low-pressure weather systems and winter storms affect the Holderness coast?
Low-pressure air weighs less, raising sea levels, which in turn produce much higher tides than normal.
134
How do small, almost-enclosed seas affect the Holderness coast?
They generate huge waves during storms. Waves move within the sea, but cannot disperse their energy.
135
How does the sea floor affect the Holderness?
It is relatively deep so waves reach the cliffs without first being weakened by friction with shallow beaches.
136
Explain central government agencies role in Holderness
The Environment Agency is responsible for coastal management (along with the local authorities). Its budget
from central government has been cut since 2010.
137
Explain the role of local government in Holderness
The local authorities are jointly responsible for coastal
management with the Environment Agency. In 2010, local-government funding was cut by central government, which restricted local councils to minimal increases in Council Tax.
138
Explain the view of different stakeholders in the local economy in Holderness
The tourist industry wants greater spending on coastal protection.
Farmers want money spent to protect their
farmland, which is of lower value than urban spaces.
Residents want guaranteed coastal protection for their homes and businesses.
Insurance companies are increasingly refusing to insure vulnerable properties.
139
Explain the view of environmental stakeholders in Holderness
English Nature and the RSPB want to protect Spurn
Head, so a continuing flow of sand southwards by longshore drift is essential. One of the most-important assets of this
spit is the protection that it gives to the mudflats of the Humber Estuary.
140
Explain terminal groyne syndrome using an example
The sea wall, groynes and rock armour at Hornsea protect part of the coast, but they also interrupt the flow of beach material by longshore drift. The beach downdrift of Hornsea, at Mappleton, is then starved of material and its cliffs are exposed to wave attack.
141
True or False
300 homes will fall into the sea between Flamborough Head and Spurn Point by 2100
False
200 homes
142
True or False
Nationally, 7000 homes will disappear due to coastal erosion by 2100.
True
Suggested by the Environment Agency
143
How much money did the East Riding of Yorkshire Council use to trial different ways of helping people adapt to living on an eroding coastline?
£1.2 million
144
What did the East Riding of Yorkshire Council spend money on?
Financial assistance to 36 households along the coast, supported 16 relocations and 43 property demolitions.
145
What does the East Riding relocation package fund?
The demolition costs for a property.
Some relocation costs (e.g. hiring a removal van) – up to a maximum of £1000.
The expenses caused by relocating to a new home – up to a maximum of £200.
146
What does the East Riding adaptation package fund?
Rollback
Assistance grants
147
What are rollbacks?
The expenses incurred as a result of an individual’s decision to replace a threatened coastal property with a new home inland. But it only covers things like planning application fees. It was introduced particularly to address the risk to caravan parks, farms and homes in areas where coastal defences are not viable.
148
What are assistance grants?
Adapt properties which may be at risk from coastal erosion in the future (e.g. relocating septic tanks/waste pipes, and changing the access routes to some properties).
149
What is the world's most densely populated country and what is the population?
Bangladesh
169 million
150
True or False
46% of the country’s population lives less than 10 metres
above sea level.
True
151
How many meters has Bangladesh’s estuarine islands sunk by in the last 50 years?
1.5 metres
152
Why are Bangladesh’s estuarine islands sinking?
Isostatic readjustment
Clearance and drainage of more than 50 large islands in
the Ganges-Brahmaputra river delta.
153
Why have Bangladesh's estuarine islands been cleared?
To grow rice to feed the country's large population.
154
In the 1960s and 70s, how did large earth embankments help Bangladesh?
Protect islands against tidal and storm-surge inundations.
155
Where can mangrove forests be found?
Along the tropical and subtropical coasts of Africa, Australia, Asia and the Americas.
156
Where is the largest mangrove forest?
In the Sundarbans region of Bangladesh, on the edge of the Bay of Bengal.
157
What are mangrove forests essential for?
Marine, freshwater and terrestrial biodiversity, because they
stabilise coastlines against erosion, collect nutrient rich sediments, and provide a nursery for coastal fish.
Protection and shelter against extreme weather events. Absorb and disperse tidal surges associated with these events.
158
True or False
81% of Bangladesh’s mangrove forested coastline is now retreating by as much as 200 metres a year
False
71%
159
Why is Bangladesh’s mangrove forested coastline retreating?
Erosion, rising sea levels and human actions that deliberately remove the vegetation.
160
In Sri Lanka how many people died in areas protected by mangrove compared to areas without protection after the Indian Ocean tsunami?
Protected = 2 people
Unprotected = 6000 people
161
What are storm surges?
Storm surges are changes in sea level caused by intense low-pressure systems – depressions and tropical cyclones – and high wind speeds.
162
3 facts about Cyclone Sidr
(wind, waves, category)
Wind speed = 223 km/hr
Wave height = 6 m
Category 4 storm
163
What caused severe flooding in low lying areas in Bangladesh?
The storm surge breached many coastal and river embankments.
164
What happened to the housing, roads, bridges and
other infrastructure in Bangladesh?
The high winds and floods damaged them.
165
What happened to the electricity, roads and waterways in Bangladesh?
Electricity supplies and communications were knocked out, and roads and waterways became impassable.
166
What happened to the water in Bangladesh?
Drinking water was contaminated by debris, and many freshwater sources were inundated with salt water.
167
Why was there a rise in the risk of disease after Cyclone Sidr in Bangladesh?
The sanitation infrastructure was destroyed.
168
How many people were ... after Cyclone Sidr in Bangladesh?
Dead and missing
Injured
Dead and missing = 4234
Injured = 55282
169
How many/much ... were damaged after Cyclone Sidr in Bangladesh?
Crops
Houses
Educational institutions
Roads
Bridges/culverts
Electricity lines
Tube wells
Crops = 685 528 hectares
Houses = 1 518 942
Educational institutions = 16 954
Roads = 8075 km
Bridges/culverts = 1687
Electricity lines = 703 km
Tube wells = 901
170
How many cattle and poultry were killed after Cyclone Sidr in Bangladesh?
1 778 507
171
What was the cost of damage to roads, embankments, sluice gates and riverbank protection after Cyclone Sidr in Bangladesh?
US$ 29.6 million
172
What caused the storm surge (Cyclone Sidr)?
- Intense low pressure (976 mb deepening to 968 mb)
- Sea shape and coastline (dangerous funnel shape allows strong northerly winds to push storm surges)
- Sea depth (shallow - increasing the height of tides and storm surges)
- High seasonal tides
- Strong northerly winds (increasing the height of the surge and tides)
173
Impacts of Cyclone Sidr in the Netherlands
It reached 3.74 metres above mean sea level.
No deaths.
Delta Works (series of dams and storm-surge barriers) was closed.
174
Impacts of Cyclone Sidr in the UK
Strong winds (gusts of over 200 km/hr in Scotland).
Coastal flooding (1400 homes) and forced evacuation.
Cliff erosion led to several properties collapsing into the sea.
Bridges were shut, and rail services in eastern counties were disrupted.
Two people died.
Hundreds of thousands of properties were protected by flood defences, and the Thames Barrier was closed to protect London.
Insurers calculated the cost of the damage at £100 million.
175
Why does climate change increase flood risk?
Warmer ocean-surface temperatures and higher sea levels are expected to make storms more intense – with stronger winds and more rain.
176
True or False
The number of tropical storms that form each year ranges from 40-60
False
70-110
(40-60 hurricanes)
177
Define adaptation
Making changes to lessen the impact of flooding - includes things like building sea walls, building storm-surge barriers and reinstating mangrove forests.
178
Define mitigation
Making efforts to reduce the emission of greenhouse
gases and so reduce the impacts of climate change.
179
What are groynes?
Timber or rock structures built at right angles to the coast. They trap sediment being moved along the coast by longshore drift – building up the beach.
180
Advantages of groynes
The built-up beach increases tourist potential and protects
the land behind it.
Groynes work with natural processes to build up the beach.
Not too expensive.
181
Disadvantages of groynes
Groynes starve beaches further along the coast of fresh sediment, because they interrupt longshore drift. This often leads to increased erosion elsewhere.
Groynes are unnatural and rock groynes can be very unattractive.
182
What are sea walls?
Made of stone or concrete at the foot of a cliff, or at the top of a beach. They usually have a curved face to reflect waves back into the sea.
183
Advantages of sea walls
Effective prevention of erosion.
They often have a promenade for people to walk along.
184
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.
185
What is rip rap?
Large rocks placed at the foot of a cliff, or at the top of a beach. It forms a permeable barrier to the sea – breaking up the waves, but allowing some water to pass through.
186
Advantages of rip rap
It is relatively cheap and easy to construct and maintain.
It’s often used for fishing from, or for sunbathing by tourists.
187
Disadvantages of rip rap
The rocks used are usually from somewhere else (e.g. granite), so they don’t fit in with the local geology and can look out of place.
It can be very intrusive.
The rocks can be dangerous for people clambering over them.
188
What are revetments?
Sloping wooden, concrete or rock structures – placed at the foot of a cliff or the top of a beach. They break up the waves’ energy.
189
Advantages of revetments
They are relatively inexpensive to build.
190
Disadvantages of revetments
They are intrusive and very unnatural looking.
They can need high levels of maintenance.
191
What are offshore breakwaters?
A partly submerged rock barrier, designed to break up the waves before they reach the coast.
192
Advantages of offshore breakwaters
An effective permeable barrier.
193
Disadvantages of offshore breakwaters
It is visually unappealing.
It’s a potential navigation hazard.
194
What is a cost benefit analysis?
They are carried out before a coastal-management project is given the go-ahead. Costs are forecast (e.g. a sea wall – its
design, building costs, maintenance, etc.) and then compared with the expected benefits (e.g. value of land saved, housing protected, savings in relocating people, etc.).
195
Define tangible
Where costs and benefits are known and can be given a monetary value (e.g. building costs).
196
Define intangible
Where costs may be difficult to assess but are important (e.g. the visual impact of a revetment).
197
What coastal defences are put in place at Hornsea?
Concrete sea walls, groynes and rock armour
198
What are the impacts of the coastal defences at Hornsea?
The groynes trap sediment and maintain the beach at Hornsea, but Mappleton downdrift has been
starved of sediment as a result. There, rapid wave attack has eroded the cliffs, so that by the 1990s, nearly 4 metres
of cliff were being eroded each year.
199
What coastal defences are put in place at Mappleton?
2 rock groynes and rock amour
200
What are the impacts of the coastal defences at Mappleton?
At Cowden, 3 km south of Mappleton, the resultant sediment starvation caused increased erosion of the cliffs
(from 2.5 to 3.8 metres a year between 1991 and 2007).
201
What coastal defences are put in place at Withernsea?
A straight sea wall which collapsed and was then replaced by a curved sea wall.
202
What are the impacts of the coastal defences at Withernsea?
The waves are now noisier when they break against the
wall, and the promenade is smaller.
The views from sea-front hotels have also been restricted. Some tourists find the rip-rap at the base of the sea wall unattractive.
203
What is beach nourishment?
The addition of sand or pebbles to an existing beach to make it higher or wider. The sediment is usually
dredged from the nearby seabed.
204
Advantages of beach nourishment
Relatively cheap and easy to maintain.
It looks natural and blends in with the existing beach.
It increases tourist potential by creating a bigger beach.
205
Disadvantages of beach nourishment
It needs constant maintenance, because of the natural processes of erosion and longshore drift.
206
What is cliff regrading and drainage?
Cliff regrading reduces the angle of the cliff, to help stabilise it.
Drainage removes water to prevent landslides and slumping.
207
Advantages of cliff regrading and drainage
Regrading can work on clay or loose rock, where other methods won’t work.
Drainage is cost-effective.
208
Disadvantages of cliff regrading and drainage
Regrading effectively causes the cliff to retreat.
Drained cliffs can dry out and lead to collapse (rock falls).
209
What is dune stabalisation?
Marram grass can be planted to stabilise dunes. Areas can be fenced in to keep people off newly planted dunes.
210
Advantages of dune stabalisation
It maintains a natural coastal environment.
It provides important wildlife habitats.
It is relatively cheap and sustainable.
211
Disadvantages of dune stabalisation
It is time consuming to plant marram grass.
People may respond negatively to being kept off certain areas.
212
What is marsh creation?
A form of managed retreat, by allowing low-lying coastal areas to be flooded by the sea. The land then becomes a salt marsh.
213
Advantages of marsh creation
It is relatively cheap, because it often involves land reverting to its original state before it was managed for agriculture.
It creates a natural defence – providing a buffer to powerful waves.
It creates an important wildlife habitat.
214
Disadvantages of marsh creation
Agricultural land is lost.
Farmers or landowners need to be compensated.
215
True or False
High tides in Khulna are rising six times faster than sea levels in the open ocean.
True
216
Why is the tide rising in Khulna (Bangladesh)?
Destruction of mangrove forests.
Embankments built to protect people from the rising tides are making the problem worse – by constricting and funnelling tidal flows, pushing water further inland, and increasing the tidal range.
217
What is Odisha’s coastal zone under stress from?
Rapid urban industrialisation
Marine transport, fishing and aquaculture
Tourism
Coastal and seabed mining
Coastal erosion
Offshore oil and natural gas production
Increase in the frequency and intensity of severe weather events, such as cyclones
Rising sea levels.
218
What is ICZM?
Integrated Coastal Zone Management
A process that brings together all of those involved in the development, management and use of the coast.
219
What is the aim of ICZM?
To establish sustainable levels of economic and social activity, resolve environmental, social and economic challenges and conflicts and protect the coastal
environment.
220
What are the UK government’s principles for coastal
management in England?
Taking a holistic approach
Adopting a long-term perspective
Pursuing adaptive management
Seeking specific solutions and flexible measures
Working with natural processes
Providing participatory planning.
221
What is hold the line?
Involves maintaining the current position of the coastline (often using hard-engineering methods).
222
What is advance the line?
Involves extending the coastline out to sea (e.g. by encouraging the build-up of a wider beach, using beach-nourishment methods and groyne construction).
223
What is managed retreat / strategic realignment?
Involves allowing the coastline to retreat, but in a managed way. It can involve the deliberate breaching of flood banks
built to protect low-quality farmland from flooding (creating salt-marsh environments).
224
What is no active intervention / do nothing?
Involves letting nature take its course and allowing the sea to erode cliffs and flood low-lying land (whilst letting the existing defences collapse).
225
What is SMP?
Shoreline Management Plan
It assesses potential erosion and flood risks, and then identifies sustainable coastal defence and management
options, which take into account the influences and needs of the human, natural and historic environments.
226
What does an economic assessment identify?
- The benefits clearly outweighed the costs.
- The benefits marginally outweighed the costs.
- The costs clearly outweighed the benefits.
227
What did the Holderness CBA conclude?
- Along the undefended parts of the coast, the 'do nothing' policy has no costs.
- Benefits outweigh the costs of continuing to protect Bridlington, Hornsea and Withernsea.
- Economic benefit of holding the line at Mappleton is similar to the cost.
- Current importance of the gas terminals at Dimlington and Easington means that benefits clearly outweigh costs.
- Spurn Point will be allowed to evolve - requiring minimal costs.
228
True or False
Decisions about whether to defend the coast are just based on a CBA and EIA.
False
They are complex decisions based on a range of factors.
229
What does engineering feasibility consider?
- Is it the right method?
- Is it achievable?
- Is it within budget?
- What are the risks?
230
What does environmental sensitivity consider?
Does the coastline include sites which are protected?
231
Give examples of area along the Holderness coast that are protected.
- Flamborough Head.
- Spurn Head.
- Hornsea Mere.
232
What does land use and value consider?
What is the coast used for and how much is the land worth?
233
True or False
Much of the Holderness coast consists of agricultural land.
True
234
How is agricultural land classified?
Grades 1-5 (1 being excellent and 5 being very poor).
235
What is the affect of allowing Flamborough Head to erode?
Sediment continues to be supplied to other parts of the coastline.
236
What is the affect of holding the line at Bridlington, Hornsea and Withernsea?
Erosion is prevented there - thus interrupting the sediment supply further south.
237
Social / economic reasons for protecting the coast.
- Agriculture is a key employer in the area - many jobs depend on it.
- Tourism is key industry - major contributor to the local economy.
238
True or False
Most coastal villages will not be at risk of erosion over the lifetime of an SMP.
True
But some individual properties are.
239
How many homes are at risk of disappearing into the sea by 2025?
Approximately 37.
240
Political reasons for protecting the coast.
- Costs have to be acceptable to the government of the day - often something has to be seen to be 'done'.
- 'Do nothing' may be a reasonable option, but it's rarely acceptable to those affected.
