Costal Landscapes and Change Flashcards
1
Q
What is the littoral zone?
A
It is a zone that stretches out into the sea and onto the shore. It is divided into 4 sections and is constantly changing.
2
Q
What are the 4 Littoral zones?
A
Backshore
Foreshore
nearshore
offshore
3
Q
What factors can effect the littoral zone?
A
Short term- waves, daily tides, seasonal storms
Long term- changes to sea level, climate change
4
Q
What are the natural processes that will cause changes to the littoral zone?
A
Sediment input from sea and rivers
Destructive waves – erodes the beach
Constructive Waves – build up the beach
Longshore drift – moves material along the coast
Tidal Range – determines where wave action occurs
5
Q
What are the human activity’s that will cause changes to the littoral zone?
A
Dredging of rivers (for navigation)
Dredging off offshore areas (material for construction)
Building of coastal defences
6
Q
What are the inputs to the coast as a system?
A
Marine- waves, tides, storm surges
Atmospheric- weather/climate, climate change, solar energy
Land- rock type and structure, tectonic activity
People- human activity, costal management
7
Q
What are the processes to the coast as a system?
A
Weathering Mass movement Erosion Transport Deposition
8
Q
What are the Outputs to the coast as a system?
A
Erosional landforms
Depositional landforms
Different types of coasts
9
Q
what Valentin’s classification of coasts?
A
Recognises that coasts can be erosional or depositional and emerging or submerging and that these effects can magnify or neutralise each other.
(circle split into 8 sections)
10
Q
What are coasts classified depending on?
A
Their Geology
Level of energy
The balance between erosion and deposition
Changes in sea level
11
Q
How can coats be classified in the long term?
A
Geology (discordant + concordant)
Sea level rise (eustatic +isostatic)
12
Q
How can coasts be classified in the short term?
A
Wave energy (high energy coast + low energy coast) Wave type (constructive + destructive)
13
Q
What are the three types of rock?
A
Igneous
Metamorphic
Sedimentary
14
Q
How is igneous rock formed?
A
Created by volcanic activity when magma or lava cools, forming crystals that are usually hard
15
Q
How is sedimentary rock Formed?
A
Formed of small particles that have been eroded, transported & deposited in layers or from remains of plants and animals
16
Q
How is metamorphic rock formed?
A
Form from other rocks changing by extreme heat and pressure.
Usually form from layers / bands of crystals and very hard
17
Q
What is costal morphology?
A
The shape and form of costal landscapes and their features
18
Q
What is costal recession?
A
Another term for costal erosion
19
Q
What is lithology?
A
The physical characteristics of particular rocks
20
Q
Give an example of an igneous rock?
A
Granite
21
Q
Give an example of an sedimentary rock?
A
Limestone and chalk
22
Q
Give an example of an metamorphic rock?
A
Gneiss and marble
23
Q
Give an example of an unconsolidated material?
A
Bolder clay (Holderness coast)
24
Q
What is the resistance and erosion rates of igneous rock?
A
Very resistant, annual recession of 1mm per year on average
25
What is the resistance and erosion rates of Metamorphic rock?
Very resistant
26
What is the resistance and erosion rates of sedimentary rock?
Thinly bedded limestone – annual recession of 2.5cm per year
27
What is the resistance and erosion rates of unconsolidated material?
1m per year average at Holderness
28
What is the permeability of igneous rock?
Impermeable very few spaces of joints for water to pass through
29
What is the permeability of sedimentary rock?
Often porous – makes susceptible to weather
30
What is the permeability of metamorphic rock?
Impermeable very few spaces of joints for water to pass through
31
What is the permeability of unconsolidated material?
Loose materials and so permeable – lost of spaces for water to pass through
32
What is strata?
Layers of rock
33
What are bedding planes?
These are natural breaks in the strata, caused by gaps in time during periods of rock formation
34
What are joints?
These are fractures, caused either by contraction as sediments dry out, or by earth movements during uplift
35
What are folds?
Formed by pressure during tectonic activity, which makes rocks buckle and crumple (Lulworth cove)
36
What are faults?
Formed when the stress or pressure to which a rock is subjected, exceeds its eternal strength
The faults then slip or move along fault planes
37
What are dips?
This refers to the angle at which rock strata lie
38
What does lithology include?
Geological structure (number and angle of strata & bedding planes)
How porous the rock is (permeability)
Permeability is linked to grain size, rock structure (e.g. crystal) etc…
Composition (e.g - limestone is soluble in rain water because it is a diluted carbonic acid – chemical weathering)
39
Describe a high energy coastline?
In the UK they tend to be Atlantic facing coats, where the waves are powerful for much of the year (Cornwall)
Where rates of erosion exceeds the rate of deposition
40
What landforms are created at high energy coastlines?
Headlands
Cliffs
Shoreline platforms
41
Describe a low energy coastline?
Sandy and estuarine coasts are generally found here
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
42
What landforms are created at low energy coastlines?
Beaches
Spits
Costal plains
43
What is a discordant coastline?
Where the geology alternates between bonds of more resistant and less resistant rock, which run at right angles to the coast
44
What is a concordant coastline?
This is where bands of more resistant and less resistant rock run parallel to the coast
45
What are Dalmatian coasts?
They are another type of concordant coastline
| They have formed as a result of a rise in sea level
46
What is a Haff coastline?
It consists of concordant features of long spits and sandy lagoons aligned parallel to the coast
47
What is a wave length?
The distance between one peak of a wave to the next corresponding peak
48
What is a wave crest?
The top of a wave (opposite of a trough)
49
What is a wave trough?
bottom of a wave (opposite of crest)
50
What is swash?
When a wave reaches the shore, the water that rushes up the beach
51
What is backwash?
The water that flows back towards the sea
52
What is wave height?
The wave height of a surface wave is the difference between the height of a crest and the trough
53
What is fetch?
How far the wind has travelled
54
What are constructive waves?
```
Linked to low energy coastlines
Low surging waves
long wavelength
Strong wash
Weak backwash
Beach gain
6-9 per minute
```
55
What are destructive waves?
```
Linked to high energy and storm weather, leads to erosion
Long fetch
High plummeting waves
Short wavelengths
Weak swash
Strong backwash
Beach loss
11-16 per minute
```
56
What is beach morphology?
It means the shape of a beach, including its width and slope (the beach profile) and features such as berms, ridges and runnels. It also includes the type of sediment (shingle, mud, sand) found at different location on the beach
57
What is a beach profile?
A cross section of a beach
58
What are the temporal factors effecting beach morphology?
Over a day, as a storm passes and destructive waves change to constructive ones as the wind drops
Between summer and winter (see next slide)
When there are changes to the climate (e.g. if global warming resulted in the UK climate becoming on average stormier, then destructive waves and ‘winter’ beach profiles would become common
59
Describe summer beaches?
Shallower profiles as constructive waves are more common.
As constructive waves are less frequent, waves energy dissipates and deposits over a wide area
The swash of a constructive wave deposits larger material at the top of the beach – creating a berm
60
Describe winter beaches?
Steeper profiles as destructive waves are more common.
As destructive waves are more frequent, berms are eroded by plunging waves
Strong backwash transports sediment offshore creating offshore bars
61
What are berms?
The shingle ridges often found towards the back of a beach
62
What are offshore bars?
Elongate ridges and mounds of sand or gravel deposited beyond a shoreline by currents and waves
63
What is abrasion?
This is when pebbles grind along a rock platform, much like sandpaper
Over time the rock becomes smooth
64
What is hydraulic action?
This is the sheer power of the waves as they smash against the cliff
Air becomes trapped in the cracks in the rock and causes the rock to break apart
65
What is corrosion?
This is when sea water dissolves certain types of rocks
| In the UK, chalk and limestone cliffs are prone to this type of erosion
66
What is attrition?
This is when rocks that the sea is carrying knock against each other
They break apart to become smaller and more rounded
67
What are the erosional landforms?
```
Headlands and bays
Wave cut notch
Structure platform
Cliff
Cave, Arch, Stack and Stump
```
68
How is a cave formed?
Caves occur when waves force their way into cracks in the cliff face
The water contains sand and other materials that grind away at the rock until the cracks become a cave
Hydraulic action is the predominant process
69
How is an arch formed?
If the cave is formed in a headland, it may eventually break through to the other side forming an arch
70
How is a stack formed?
The arch will gradually become bigger until it can no longer support the top of the arch
When the arch collapses, it leaves the headland on one side and a stack (a tall column of rock) on the other
71
How is a stump formed?
The stack will be attacked at the base in the same way that a wave-cut notch is formed
This weakens the structure and it will eventually collapse to form a stump
72
How is a cliff formed?
Cliffs are shaped through erosion and weathering
| Soft rock erodes quickly and forms gentle sloping cliffs, whereas hard rock is more resistant and forms steep cliffs
73
How are wave cut notches and shoreline platforms formed?
The sea attacks the base of the cliff between the high and low water mark
A wave-cut notch is formed by erosional processes such as abrasion and hydraulic action - this is a dent in the cliff usually at the level of high tide
As the notch increases in size, the cliff becomes unstable and collapses, leading to the retreat of the cliff face
The backwash carries away the eroded material, leaving a wave-cut platform
The process repeats. The cliff continues to retreat
74
How are headlands and bays formed?
Bands of soft rock such as clay and sand are weaker therefore they can be eroded quickly This process forms bays
A bay is an inlet of the sea where the land curves inwards, usually with a beach
Hard rock such as chalk is more resistant to the processes of erosion
When the softer rock is eroded inwards, the hard rock sticks out into the sea, forming a headland
75
Give some examples of sediment transportation?
Angle of wave attack
Currents
Tides
Process of long shore drift
76
Give some examples of depositional landforms?
Beach
Tombolo
Spit
Offshore bar
77
What is traction?
Relatively large and heavy rocks are rolled along the seabed
78
What is saltation?
Smaller and lighter rock bounce along the seabed
79
What is suspension?
How lighter sediment is carried
80
What is solution?
How dissolved sediment is carried
81
What are tides?
They are changes in the water level of sea and oceans
Caused by the gravitational pull of the moon and to a lesser extent, the sun
The UK coastline experiences two high and two low tides a day
82
What is the tidal range?
The relative difference between high and low tides
83
What is long shore drift?
The movement of material along a coast by waves which approach at an angle to the shore but recede directly away from it
84
What are the depositional landforms?
```
Spits
Beaches
Bars
Tombolo's
Cuspate forelands
```
85
What are spits?
A spit is an extended stretch of sand or shingle jutting out into the sea from the land
Spits occur when there is a change in the shape of the landscape or there is a river mouth
86
How is a spit formed?
Sediment is carried by longshore drift
When there is a change in the shape of the coastline, deposition occurs
A long thin ridge of material is deposited
This is the spit
A hooked end can form if there is a change in wind direction
Waves cannot get past a spit, therefore the water behind a spit is very sheltered
Silts are deposited here to form salt marshes or mud flats
87
What is a bar?
Sometimes a spit can grow across a bay, and joins two headlands together
This landform is known as a bar
They can trap shallow lakes behind the bar, these are known as lagoons
Lagoons do not last forever and may be filled up with sediment
88
what is a beach?
Beaches are made up from eroded material that has been transported from elsewhere and then deposited by the sea
For this to occur, waves must have limited energy, so beaches often form in sheltered areas like bays
89
How are beaches formed?
Constructive waves build up beaches as they have a strong swash and a weak backwash
90
How are tombolo's formed?
A tombolo is formed when a spit connects the mainland coast to an island
A spit is a feature that is formed through deposition of material at coastlines. The process of longshore drift occurs and this moves material along the coastline
91
What is a cuspate foreland?
A large, triangular area of coastal deposition, which is dominated by many shingle ridges and is often terminated on the landward side by poorly drained terrain
It is the result of a long episode of local marine aggradation under wave advance from two dominant directions
92
What are erosional processes effected by?
Wave type
Wave size
Lithology
93
What is the sediment cell concept?
Sediment cells are areas along the coastline and in the nearshore area where the movement of material is largely self-contained
94
What are the sources of the sediment cell?
```
Erosion of cliffs
Onshore currents supplying sediments to the shore
Land sediments eroded by rivers
Wind blown sediments from land
Subaerial processes
```
95
What are the transfers of the sediment cell?
```
Longshore drift
Wave Transport through swash and backwash
Tides moving sediments in and out
Currents- localised or large scale
Wind along shore or on- and off shore
```
96
What are the sinks in the sediment cell?
Backshore depositional landforms
Foreshore depositional landforms
Nearshore depositional landforms
Offshore sediment deposition to deep offshore waters
97
What is the sediment budget?
The amount of sediment available within a cell is called a sediment budget
98
What is negative feedback in a sediment cell?
Wave erosion causes rock falls, which then protect the base of a cliff from further erosion
99
What is positive feedback in a sediment cell?
Damage to sand dunes during storms conditions, which may create a 'blow out' allowing the wind to move more sand away, preventing grasses from re-growing
Allowing further erosion to occur
100
What is weathering?
The gradual breakdown of rock, in situ, at or close to the ground surface
101
What is mass movement?
The movement of weathered material down slope, as a result of gravity
102
What are the three types of weathering?
Chemical
Biological
Mechanical
103
What is chemical weathering?
The erosion or disintegration of rocks, building materials, etc., caused by chemical reactions (chiefly with water and substances dissolved in it) rather than by mechanical processes
104
What is mechanical weathering?
Any of the various weathering processes that cause physical disintegration of exposed rock without any change in the chemical composition of the rock: Collision between rock surfaces can cause mechanical weathering
105
What is biological weathering?
is the weakening and subsequent disintegration of rock by plants, animals and microbes
Growing plant roots can exert stress or pressure on rock. Although the process is physical, the pressure is exerted by a biological process (i.e., growing roots)
106
What does resultant of mass movement depend on?
The angle of the slope or cliff
The rock type and its structure
The vegetation cover
How the wet ground is
107
What are the types of mass movement?
```
Soil creep
Mudflow
Slump
Rock fall
Landslide
```
108
Why are sea levels rising?
Ice caps and glaciers are melting
| Thermal expansion
109
What causes the sea level to change?
Terrestrial water storage, extraction of ground water, building of reservoirs, changes n run off, and seepage into aquafers
Subsidence in river delta region, land movements, and tectonic displacements
surface and deep ocean circulation changes storm surges
As the ocean warms the water expands
Exchange of the water stored on land by glaciers and ice sheets with ocean water
110
What case study would I use for sea level change?
Kiribati
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-level
113
What causes natural climate change?
Eccentricity
Tilt
Precession
114
What is eccentricity?
When the earth encounters more variation in the energy that it receives from the sun when earths orbit is elongated than it does when earths orbit is elongated than it does when the earths orbit is more circular
115
What is tilt?
The tilt of the earths axis varied between 22.2 and 24.5degreese
The greater the tilt angle is, the more solar energy the poles receive
116
What is precession?
A gradual change, or "wobble" in the orientation of earths axis affects the relationship between earths tilt and eccentricity
117
What are some emergent coastlines?
Raised beaches
| Fossil/ relic cliffs
118
What are some submergent coastlines?
A ria
A fjord
A fjard
Dalmation coasts
119
What are raised beaches?
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
Example- Isle of Arran
120
What are Fossil/Relic cliffs?
as the land rose as a result of isostatic recovery, former shoreline platforms and their beaches were raised above the present sea level
Example- Isle of Arran
121
What is a Ria?
They are one of the most distinctive features associated with rising sea levels
They form when valley in a dissected upland area are flooded
Example- devon
122
What is a fjord?
They are long and steep sided with a U shaped cross-section and hanging valleys
Formed when deep glacial troughs are flooded by a rise in sea level
Example- New Zealand
123
What is a Dalmatian coast?
They are similar to rias
In this case, the rivers flow almost parallel to the coast- rather than right angles to it
Example- Croatia
124
What is a fjard?
It is a flooded inlet with a low rocky banks on either side formed by post-glacial drowning of glaciated lowland rocky terrain
Example- the Gulf of Finland.
125
What case study would I use for a rapid costal retreat?
Holderness (Yorkshire)
126
What are factors effecting costal erosion?
```
Geology
Coastal defences
Marine Processes
Weakly consolidated rocks
Subaerial processes
Offshore dredging
Large destructive waves
Large scale mas movement
Constant weathering
Small constructive waves
Resistant rock
```
127
What case study would I use for dredging?
Australia
128
What case study would I use for sea level rise?
The Nile Delta
129
What are factors effecting rates if recession?
Wind direction
Tides
Weather systems
130
What case study's would I use for local and global influences on costal flooding?
Bangladesh
North sea storm serge's
Typhoon Haiyan, Philippines
131
What are some of the costal risks from global warming?
```
Sea level rise
Delta flooding
Tropical cyclones
Storm surges
Wind and waves
Costal erosion
```
132
What case study's would you use when comparing the consequences of costal flooding?
Australia
| Philippines
133
What case study would I use when talking about a country trying to mitigate sea level rise?
Maldives
134
What are some hard engineering strategies?
```
Groynes
Rip rap
Sea wall
Revetment
Offshore breakwaters
Gabions
```
135
What are some soft engineering strategies?
Beach nourishment
Cliff drainage
Dune stabilisation
Cliff regrading
136
What case study would I use when talking about coastal engineering management?
Colwyn bay
137
What case study would I use when talking about decision making?
Tal-y-bont, Mid wales
138
What is the appropriate location for a groyne?
High value frontages influenced by strong long-shore processes where nourishment or recycling are undertaken
Best on shingle beaches or within estuaries
139
What is the cost of groynes?
Moderate, but must include for recycling or npurishment
140
What is the effectiveness of groynes?
Good on exposed shorelines with a natural shingle upper beach
Can also be useful in estuary stop deflect flows
Unlimited structure life for rock groynes
141
What are the benefits of groynes?
Encourages upper beach stability and reduces maintenance commitment for recycling or nourishment
142
What are the problems of groynes?
Disrupts natural processes and public access along upper beach
143
What are the appropriate locations for beach nourishment/ replenishment?
All locations, including those with limited blown sand for natural recovery
144
What is the cost of beach nourishment/ replenishment?
Low to moderate
| But requires ongoing maintenance
145
What is the effectiveness of beach nourishment/ replenishment?
Short term defence against erosion, and enhancement of natural recovery, moderate resistance to single storms
Enhanced by fencing and vegetation transplanting, and can be successfully used to burry hard defences
146
What is the benefits of beach nourishment/ replenishment?
Accelerates natural recovery of foredunes and provides short term defence against single severe storms
147
What are the problems with beach nourishment/ replenishment?
Removes material from other sites
Possibly transferring erosion or environmental damage to a different frontage
May introduce beach debris, non indigenous sediment and/or vegetation, potentially damaging local economy
148
What the appropriate locations for offshore breakwaters?
Exposed dunes of high ecological and landscape value
149
What is the cost of offshore breakwaters?
Moderate to high, and may need some shoreline maintenance
150
What is the effectiveness of offshore breakwaters?
Causes lee side accretion, but least effective during storm surge conditions, unlimited structure life
151
What are the benefits of offshore breakwaters?
Natural processes are only partly disrupted, allowing dunes to stabilise
Rocks create new intertidal habitat
152
What are the problems with offshore breakwaters?
May cause a navigation hazard
Visually intrusive at low tide
Disrupt amenity use of beach
153
What are the appropriate locations for seawalls?
Exposed frontages with extensive and high value backshore assets
154
What are the costs of sea walls?
High but low maintenance
155
What is the effectiveness of sea walls?
Provides good medium long term protection, but continued erosion will cause long term failure
156
What are the problems with sea walls?
Continued erosion may cause undermining and structural failure
Complete disruption of natural beach-dune processes
157
What are the appropriate location for riprap?
Sites suffering severe and ongoing erosion where important and extensive backshore assets are at risk
158
What is the cost of rip rap?
High but with relatively low maintenance
159
What is the effectiveness of riprap?
Low risk option for important backshore assets
| Permeable face absorbs wave energy and encourages upper beach stability
160
What are the problems of riprap?
Strong landscape impact
| Can alter dune system permanently as sand tends not to build up over the rocks if beach erosion continues
161
What is the appropriate locations for revetments?
Sandy beach sites suffering periodic moderate to severe erosion where backshore assets are at risk
Useful for estuary
162
What is the cost of revetments?
Moderate but require maintenance
163
What is the effectiveness of revetments?
Provides reasonable fixed defences, but have a limited life of 5-10years due to deterioration of the baskets
164
What are the benefits of revetments?
Useful solution where Armor rock is considered too costly
Various forms available
Can be buried by sand and vegetation
Permeable face absorbs wave energy and encourages upper beach stability
165
What are the problems of revetments?
Limited life, leading to unsightly and hazardous wire baskets along beach and the release of non-indigenous cobbles to the beach system
Wire affected by saltwater, vandalism and abrasion
166
What does sustainable costal management mean?
Managing current and predicted future risks to the wider coastal zone in terms of people’s economic livelihood, social well-being and local culture and environmental impacts
167
What is the ICZM?
Integrated Coastal Zone Management
) is a process for the management of the coast using an integrated approach, regarding all aspects of the coastal zone, including geographical and political boundaries, in an attempt to achieve sustainability
168
What are the four main approaches of costal management?
Advance the line- Building of new defences on the seaward side of the coast.
Land reclamation
Hold the line- Creation/maintenance of defences along existing coastline
Managed/strategic retreat/realignment- Management and monitoring of the coastline to allow coastal processes to take-over gradually
No active intervention- no active management or monitoring of the coastline
169
What processes does a plan to build costal defences go through?
Stakeholder interests
Engineering feasibility
Environmental impact assessment
Budget/cost
170
What is the EIA?
Environmental Impact Assessment
171
What are the stages of the EIA?
```
Screening
Scoping
Assessment
Consultation
Decision making
```
172
What case study would I use for costal management in the developing world?
Namibia
