Coasts Flashcards
(184 cards)
1
Q
What is a system?
A
A system is a collection of stores and transfers/flows that work together by a driving process
2
Q
What are elements?
A
The key parts of the system
3
Q
What are attributes?
A
The key characteristics of the elements
4
Q
What are relationships?
A
How the different elements work together
5
Q
What are boundaries?
A
the limits of the system
6
Q
What are flows/transfers/fluxes?
A
The movement of energy or matter through the system from one store to another
7
Q
What are inputs?
A
additions of matter or energy that enter the system
8
Q
Examples of marine inputs
A
Waves, tides and salt spray
9
Q
Examples of atmosphere inputs
A
Sun, air pressure, wind speed and direction
10
Q
What are human inputs
A
pollution, recreation, settlement and defences
11
Q
What are outputs?
A
Losses of matter that leave the system
12
Q
What are some examples of outputs?
A
ocean currents, rip tides, sediment transfer and evaporation
13
Q
What are components/store?
A
Where amounts of energy of matter are held in store until such a time that an appropriate process is put in place to move them.
14
Q
What is a sediment cell?
A
bordered by prominent headlands where the movement of sediment in contained and the flows of sediment act in dynamic equilibrium
15
Q
What is an open system?
A
Both mass and energy are allowed to transfer across system boundary
16
Q
What is a closed system?
A
May be a flow of energy into or out of the system but the matter flow takes place across the system boundary.
17
Q
What are isolated systems?
A
They do not exist and so are only theoretical
18
Q
What is positive feedback?
A
When a process increases the change in a system.
19
Q
What is negative feedback?
A
When a process seeks to counter the change and maintain equilibrium
20
Q
What is dynamic equilibrium?
A
The balanced state of a system when its inputs and outputs are equal
21
Q
How are waves mostly formed?
A
by wind
22
Q
Wind moves from high to low pressure. True or false?
A
True
23
Q
How is dynamic equilibrium affected by the sand supply?
A
Sand is food for beaches, gives shorelines protection from the waves, being starved of sand can cause higher rates of erosion
24
Q
How is dynamic equilibrium affected by waves?
A
The erosive action of a wave is greatest when the wave is high. The angle at which they strike a beach and how much sand they are carrying can also influence the rate of erosion
25
How is dynamic equilibrium affected sea level?
| Sea level rising....
Sea level rising causes change in the systems
26
How is dynamic equilibrium affected by shorelines?
| Clue = storms and erosion
Shorelines move back and forth between storms and their location can either decrease or increase erosion rates
27
How does temperature influence the coastline?
| processes
Onion-skin weathering, freeze-thaw weathering, changes in state
28
How do waves influence coastlines?
| processes E D T
erosion, deposition and transportation
29
What does feedback mean in a system?
| AR
an automatic response to change in a system
30
What do waves represent?
a transfer of energy
31
How are waves created?
| detailed answer FD and A
- Air moving across the water
- frictional drag disturbs the surface and forms ripples or waves
IN THE OPEN SEA
- there is little horizontal movement, instead there is an orbital movement of particles
32
What factors affect the size and strength of waves?
- Strength of wind (pressure gradient)
- Duration of wind (longer = more powerful)
- the fetch ( distance over open water in which the wind blows)
33
Wave length
the distance between successive crests
34
Crest
Highest point of single wave
35
Wave Frequency
The time for one waves to travel the distance of one wavelength
36
What is a neap tide?
Moon is at right angles to sun, small tidal range
37
What are tides caused by?
Gravitational pull from the alignment of the moon and sun
38
What is spring tide?
Sun and moon are aligned, large tidal range
39
Why do waves break?
## Footnote
1) waves become .. and the .. of the particles change to an ..
2) wavelength and velocity both ..
3) the wave height .. causing water to .. from behind and .. to a point where it starts to ..
4) waves rush up the beach as .. and down as ..
1) waves become shallower and the circular orbit of the water particles change to an elliptical shape
2) wavelength and velocity both decrease
3) the wave height increases causing water to back up from behind and rise to a point where it starts to topple over
4) waves rush up the beach as swash and down as backwash
40
Features of high energy coastlines
-powerful energy
-erosion exceeds deposition
-headlands, cliffs and wave-cut platforms
-frequently exposed to storms
41
Features of low energy coastlines
-not powerful waves
-deposition exceeds erosion
-landforms include beaches and spits
42
Wave refraction
| think of wave fronts
The distortion of wave fronts as they approach and indented shoreline.
43
Storm surge
the pushing of water against a coastline abnormally high levels, usually a combination of extreme low pressure and high tides
44
Tidal range
the vertical distance in height of sea level between high and low tide
45
Ocean current
Large scale movement of water in an ocean
46
Spring tide
Tides that occur twice a month when the sun and moon are in alignment with the Earth.
47
What are ocean currents caused by?
| 3 things
- tides
- wind
- thermohaline circulation
48
Neap Tide
Tides that occur twice a month when the sun and moon are at right angles to the earth
49
What is thermohaline circulation?
Deep ocean currents are driven by differences in the water's density which is controlled by temperature (thermo) and salinity (haline)
50
What is traction?
large stones & boulders are rolled and slid along the seabed and beach by moving seawater.
51
Is traction high or low energy coastlines?
High energy
52
What is saltation?
Small stones bounce along the sea bed and beach. Associated with high energy coastlines.
53
What is suspension?
Very small particles of sand and silt are carried along by moving water. Causes a murky appearance of the water.
54
What is solution?
Dissolved materials are transported within the mass of moving water
55
What is a sediment cell?
A stretch of coastline that is usually bordered by two headlands
56
How many sediment cells are there in the UK?
11
57
Are sediment cells closed or open systems?
In theory they are closed as the sediment is contained.
58
What is a sediment budget?
| Think of the system and inputs, outputs and stores
The balance between changes in the volume of sediment held within the system and the volume of sediment entering or leaving the system.
59
What is a positive budget?
There are more inputs than outputs. More material is added to the cell and so there is a net accretion of material. The shoreline builds towards the sea.
60
What is a negative budget?
There are more outputs than inputs. More material is removed from the cell rather than is added. The shoreline retreats landward.
61
What is Weathering?
The disintegration of rock in situ
62
What is chemical weathering?
Both rain and water contain chemicals that can react within chemical compounds in the rock, altering it's structure
63
What is biological weathering?
Living organisms can contribute towards the weathering of coastal rocks through the activity of plants and animals.
64
What is physical weathering?
Internal pressures are exerted on rock as a result of changes in the physical structure within it's mass.
65
What is slumping/rotational slip?
- Cliffs formed from boulder clay, material deposited by glacial period, are susceptible to high rates of coastal erosion.
- cliff faces are concave shaped, rather than vertical
- The soft boulder clay is quickly eroded through hydraulic action and abrasion
- Rain is also another factor causing the soil to become saturated and for the cliff to slump.
66
What are landslides?
- Erosion is caused by waves at the base of the cliff
- this creates a wave cut notch in the base of the cliff.
- As this increases in size, the weight of the cliff become too much to support and so the cliff collapses causing a landslide
67
What is rockfall?
When rock fragments break away from the cliff face often due to freeze-thaw weathering.
68
What is a land/mud slide?
They occur when saturated soil and weak rock flow down a slope. These typically occur where cliffs are made up of boulder clay.
69
What is mass movement?
the gradual or sudden movement of consolidated material and unconsolidated material due to gravity
70
What is talus?
accumulation of weathered material
71
What is solifluction?
Downslope movement of a waterlogged regolith
72
What is runoff?
| heavy rain
When heavy rain washes material from the surface of a cliff over the edge and down onto the shore
73
What is soil creep?
Damp soil moves very slowly down the slope as the weight of water pushes it forwards.
74
What is a discordant coastline?
A coast where bands of different rock type run at right angles to the coast
75
What is a concordant coastline?
A coast where layers of differing rock types run parallel to the coast
76
Why are beaches important?
They are the largest temporary store in the coastal system
77
Why are beaches only temporary?
| Think of destructive and constructive waves
Beach accretion happens during a prolonged period of constructive waves. During localised storms, destructive waves are prone to excavating beaches, removing vast quantities of sediment and exposing previously covered landforms
78
What are runnels?
a series of ridges and troughs running parallel to the coast near the low water mark.
79
What are runnels formed by?
By deposition during backwash when the water runs back to the ocean.
80
What are ripples?
Ripples are relatively small elongated ridges that form on the beach
81
How are ripples formed?
waves and currents flow across loose sand which is dragged along the bottom and is piled up to form ripples
82
What are cusps?
semicircular shaped depressions with courser material around the edge and finer material in the middle
83
How are cusps formed?
by a collection of waves reaching the same point and backwash scouring out the finer material in the centre
84
What are berms?
Small ridges that form near the high tide mark which are deposited by the swash of constructive waves
85
What are storm beaches?
A ridge found near the back of the beach composed of larger sediment, deposited by waves during storm events -waves don' usually affect this part of a beach
86
What are drift aligned beaches?
Where waves approach the coastline at an angle, the swash moves material up the beach in that direction. The backwash returns at right angles. This repetition causes material to drift along the beach
87
What is a barrier island?
A long thin sandy stretch of land, oriented parallel to the mainland coast that protects the coast from the full force of powerful storm waves.
88
What sits between a barrier island and the mainland?
a calm, protected body of water such as a lagoon or bay
89
How does a spit form?
Where the coastline bends, longshore drift carries material and there is a build up of more sand and shingle where it is more sheltered. This repeats over a certain period.
90
What is a compound spit?
| R SG
A spit that shows evidence of a series of sequential growth and recurvature
91
What happens to waves in winter?
The more energetic waves erode and transport sediment offshore (perhaps forming an offshore bar)
92
What happens to waves in summer?
Less energetic waves move material onshore building up a steeper beach profile
93
What are tombolos?
Where a spit forms on a coastline where there is a small offshore island and the ridge of beach sediment is deposited tomards the small island, a tombolo is formed. Ridge of sediment attaches to offshore island.
94
What is a bar?
Where a spit develops across a bay
95
What is succession?
| change to a sand dune
the sequential change in vegetation in an area over time, from a colonising species to a climax community
96
Primary succession
A vegetation succession that takes place on a surface where no soil or vegetation has formerly existed
97
Secondary succession
a vegetation succession which develops on land which has previously been vegetated e.g. after a forest fire
98
Climatic climax vegetation
| think of balance
a vegetation community that is in balance with the environmental conditions of the area and will not change as long as the conditions remain unchanged.
99
Xerosere
plant succession under dry conditions
100
Lithosere
Rocky conditions
101
Psammosere
Sandy conditions
102
Hydrosere
plant succesion which begins on water-logged or submerged environments
103
Halosere
saltwater conditions
104
Hydrosere
fresh water
105
What are sand dunes?
Accumulations of sand shaped into mounds by the wind and they can be thought of as systems in their own right
106
Humus
Organic matter in soil that is derived from the breakdown of plant and animal matter. To be classified as humus it has to be completely broken down. It gives soil it's brown colour. More humus equals greater soil fertility.
107
What are salt marshes and mud flats?
| halosere or hydrosere?
They are both halosere environments
108
Salt marshes
A tidal landform consisting of silt and mud - often located landward of a spit
109
What is eustatic change?
When the sea level itself rises or falls - global scale
110
What is isostatic change?
When the land rises or falls relative to the sea - local scale
111
Natural localised isostatic changes example?
The Mississippi Delta has sunk by 165m in the last 10,000 years due to the weight of sediments in the river basin
112
What can relative sea level fall result from?
- sea level falling whilst the land surface rises, remains stationary or subsides at a slower rate
- sea level remaining stationary whilst the land rises
- sea level rising whilst the land rises at a faster rate
113
What can relative sea level rise result from?
- sea level rising whilst the land subsides, remains stationary or rises at a slower rate
- sea level remaining stationary whilst the land subsides
- sea level falling whilst the land subsides at a faster rate.
114
How long have sea levels been stable for up until now?
The last 3000 years according to the IPCC
115
From the 19th century to the 20th century how much did sea levels rise by?
1.7mm per year
116
From 1993 to 2010, how much did sea level rise per year increase to?
3.2mm per year
117
Example of sea level rising affecting communities 1. Kiribati
33 islands in NE Australia, All islands are less than 1m below sea level and are predicted to be underwater in the next 20-30 years
118
Example of sea level rising affecting communities 2. Louisiana
Ile de John Charles and its residents are the first "climate refugees" in the USA
119
How much will sea levels rise by 2100 according to the IPCC?
0.3-1m
120
What is an emergent coastline?
A coastline existing due to falling sea levels - occurs during isostatic recovery
121
What is a raised beach? EMERGENT
- Beaches which are above high tide level
- They are flat and covered by sand/pebbles
- Experience succession
- Raised beaches can be seen on the Scottish islands of Islay, Jura, Colonsay and Mull
122
What is a fossil cliff? EMERGENT
- Steep slope at the back of a raised beach
- Wave-cut notches, caves and arches may be evident
123
What is a submergent coastline?
A coastline existing because of a rise in sea level
124
What is a ria? SUBMERGENT
A drowned river valley which:
- has a V-shaped cross-section
- Are an estuarine coastline
- Are the most common coastal landforms
125
What is a fjord? SUBMERGENT
- Fjords are deeper than rias, particularly inland, as they were originally the flat-bottomed U-shaped valley carved out by a powerful glacier
- They have a relatively straight profile
- Maybe deeper than the adjacent sea
126
What is a dalmation coast? SUBMERGENT
- Where a landscape of valleys and ridges are parallel to the coastline the low parts of the valleys will be flooded when sea level rises
- The exposed tops of the ridges become small offshore islands parallel to the coast
- The best known example of this is the Dalmatian Coast in Croatia that the landform is named after
127
What is soft engineering?
A process which works with nature to lessen the impact of processes
128
Why should we choose soft engineering?
It works with nature and allows process is to continue happening but in a more controlled way. It is more sustainable and better for the environment.
129
What is Beach replenishment?
Sound is replaced along the beach often from just off the coastline.
130
What is an advantage of beach replenishment?
It doesn't look artificial
131
What are disadvantages of beach replenishment?
It doesn't prevent longshore drift. The dredger is noisy and so it kills marine life
132
What is the cost of beach replenishment?
expensive
133
What is managed retreat?
Removing existing defences and allowing low lying land behind them to flood
134
What is an advantage of managed retreat?
Marshland allows for habitats and a natural defence
135
What is a disadvantage of managed retreat?
Allows flooding which causes conflict
136
What is the cost of managed retreat?
Cheap
137
What is cliff regrading and drainage?
Reducing angle of a cliff to stabilise it
138
What are advantages of cliff regrading?
Prevents landslides and slumping which means it's effective on clay and loose rock cliffs
139
What are disadvantages of cliff drainage and regrading?
Causes the cliff to be dried out and therefore collapse, effectively causing a retreat
140
What is the cost of cliff regrading?
Cheap
141
What is dune stabilisation?
Planting marram grass
142
What are advantages of dune stabilisation?
The natural environment is protected and wildlife habitats are created
143
What are disadvantages of dune stabilisation?
Time consuming
144
What is the cost of dune stabilisation?
Cheap
145
What is hard engineering?
A process using man-made structures to prevent natural coastal processes
146
What is a sea wall?
A concrete barrier which absorbs/deflects the waves
147
What are the advantages of sea walls?
very effective as long as they are maintained and repaired
148
What are disadvantages of sea walls?
the initial cost is expensive and also it makes the base weak so it's expensive to maintain
149
What is the cost of sea walls?
approximately £6000 per metre
150
What is a groyne?
wooden fences/wall made from piles of rocks or wood built out into the sea
151
What are the advantages of groynes?
reduces longshore drift
152
What are disadvantages of groynes?
prevents the sand from moving down the coast and so erosion rates increase further down the coast due to sediment starvation
153
What is the cost of groynes?
£1000 per metre - wood
£1000 per cubic metre - rocks
154
What is Rip Rap?
A Wall made from hard rocks/granite at the base of a cliff`
155
What are the advantages of rip rap?
Absorb energy of waves and let water drain through them
156
What are disadvantages of rip rap?
Some erosion still occurs environmentally, ugly and easily moved by powerful waves
157
What is the cost of rip rap?
£1000 per metre
158
What is a revetment?
sloping concrete/wooden defence facing the sea
159
What are the advantages of revetments?
absorbs wave energy
160
What are disadvantages of revetments?
less durable and need replacing more often
161
What is the cost of revetments?
£4500 per metre
162
What is an offshore breakwater?
It faces parallel to the coast so that waves are forces to break reducing wave energy
163
What are the advantages of offshore breakwaters?
They are effective and don't spoil aesthetics
164
What are disadvantages of offshore breakwaters?
Difficult and costly to maintain
165
What is the cost of offshore breakwaters?
£1.5 million for 1
166
What is human intervention?
When humans get involved in natural processes
167
What is a cost-benefit analysis (CBA)?
Carried out before a coastal management project is given the go-ahead. Costs are forecast and then compared to the expected benefits.
168
What are tangible costs?
Where costs and benefits are known and can be given monetary value
169
What are intangible costs?
Where costs may be difficult to assess but are important
170
What would happen if costs outweigh the benefits?
The project is unlikely to go ahead
171
What is a holistic approach?
The entire coastal zone is included in the management plans - instead of just short stretches of coast. It's a long term approach that seeks to achieve a balance between natural processes and human concerns.
172
What are Shoreline Management Plans?
Extremely detailed comprehensive documents, based on the sediment cell principle that intervention will be largely self contained within each cell.
173
What is a key feature of an SMP?
- Risk asses the evolution of the coast
- Provide a framework to address the risks to people and to the historic, natural and built environments
- address the risks in a sustainable way
- aim to be sustainable
174
What is hold the line?
maintaining the current position of the coastline (hard engineering)
175
Example of hold the line..
Sheringham in Norfolk
176
What is advance the line?
extending the coastline out to sea by encouraging the build up of a wider beach, using beach nourishment methods and groyne construction
177
Example of advance the line..
Sea palling in Norfolk
178
What is managed retreat?
allowing the coastline to retreat on a managed way
179
Example of managed retreat..
Medmerry in West Sussex
180
What is do nothing?
Letting nature take its course and allowing the sea to erode cliffs and flood low-lying land and allowing existing defences to collapse
181
Example of do nothing..
Kynance cove, Cornwall
182
What is Integrated Coastal Zone Management?
The process that brings together all of those involved in the development, management and use of the coast
183
What is the aim of ICZM?
to establish sustainable levels of economic and social activity, resolve environmental, social and economic challenges and conflicts and also protects the coastal environment.
184
Where and when did ICZM originate?
Rio in 1992
