Topic 2: Coastal Landscapes and Change Flashcards
(91 cards)
1
Q
dynamic equilibrium
A
where landforms and processes are in a state of balance
2
Q
negative feedback
A
the regulation and reduction of a natural process
3
Q
closed system
A
there are no inputs or outputs of matter from an external source
4
Q
open system
A
where energy and matter can be lost to and gained from an external source
5
Q
positive feedback
A
enhances and speeds up processes, promoting rapid change
6
Q
geology
A
rock type
7
Q
littoral zone
A
the boundary between land and sea which stretches out to sea and onto the shore (coastal zone)
8
Q
backshore
A
above the influence of waves
9
Q
foreshore
A
inter-tidal or surf zone
10
Q
nearshore
A
breaker zone
11
Q
offshore
A
beyond the influence of waves
12
Q
how can coasts be classified?
A
- geology
- energy level
- balance between erosion and deposition
- changes in sea level
13
Q
coastal morphology
A
the shape and form of coastal landscapes and their features
14
Q
lithology
A
geological structure/physical characteristics of rocks:
- strata
- bedding planes
- joints
- folds
- faults
- dip
15
Q
rate of coastal recession
A
the speed at which the coast erodes, affected by:
- geology
- lithology
- weathering
- mass movement
- wave energy
- absence of beach
- rising sea levels
- human activities e.g. coastal defences
16
Q
concordant coast
A
bands of more-resistant and less-resistant rock run parallel to the coast
17
Q
Dalmatian coast
A
- concordant coastline formed from a rise in sea level
- e.g. in Croatia
- valleys flood leaving tops of ridges above surface of sea as offshore islands
18
Q
Haff coast
A
concordant coastline which consists of long spits of sand and lagoons aligned parallel to the coast
19
Q
discordant coast
A
bands of more-resistant and less-resistant rock run at right angles to the coast
20
Q
constructive waves
A
- strong swash
- weak backwash
- beach gain (deposition)
- long wavelength
21
Q
destructive waves
A
- weak swash
- strong backwash
- beach loss (erosion)
- short wavelength
22
Q
abrasion
A
- wave breaks at base of cliff
- transported material hurled at the cliff
- chips away at the rock
- grinding away of bedrock by fragments of rock
23
Q
hydraulic action
A
- air trapped under high pressure as waves advance
- air ‘explodes’ outwards as waves retreat
- joints widen and rocks fracture
24
Q
solution
A
- breaking down of rock by chemical action
- weak acids in seawater dissolve alkaline rock
25
attrition
- gradual wearing down of rock particles by impact/abrasion
- reduces particle size
- makes stones rounder/smoother
26
differential erosion
the selective erosion of areas of weakness as opposed to more-resistant areas/types of rock
27
erosional landforms
- headlands and bays
- cliffs
- caves and arches
- stacks and stumps
- wave-cut notches
- shoreline platforms
28
wave-cut notch
- waves break against foot of cliff
- begin to undercut the cliff
- notch gets bigger
- rock above becomes unstable
- upper part of cliff collapses
29
cave, arch, stack, stump
- waves erode joints and faults to form caves
- caves made larger until an arch is formed
- erosion and weathering
- top of arch collapses to leave a stack (isolated rock pillar)
- stack eroded to leave a stump (only visible at low tide)
30
longshore drift
- the movement of sand and shingle along the coast
- waves approach beach at an angle from prevailing wind direction
- swash carries some material obliquely up beach (at an angle)
- backwash carries material directly down the beach/at right angles to the shore under gravity
- sediment moves along beach
31
traction
large and heavy rocks are rolled along the seabed
32
saltation
smaller and lighter rocks 'bounce' along the seabed
33
suspension
lighter sediment carried in water
34
solution
dissolved sediment carried in water
35
tides
- changes in water level of seas and oceans
- caused by gravitational pull of the moon (and sun)
36
tidal range
- difference in height between high and low tides
- high tidal range = powerful tidal currents
37
depositional landforms
- spits
- recurved spits
- double spits
- beaches
- offshore bars
- barrier beaches (bars)
- tombolos
- cuspate forelands
38
spit
- sand/shingle moved along coast by LSD
- coastline suddenly changes direction
- sediment builds up and spit forms
- end of spit can curve round due to wave refraction
- salt marsh develops behind
39
beaches
- deposition in low-energy environments e.g. bays
- sand or shingle beaches
- swash-aligned beaches (sediment moves up and down beach)
- drift-aligned beaches (sediment transferred by LSD)
40
offshore bars
- submerged (or partly exposed) ridges of sand or coarse sediment
- created by waves offshore from the coast
41
barrier beaches (bars)
- beach/spit extends across a bay to join two headlands
- trap water behind them to form lagoons
42
tombolos
- beach (or ridge of small sand and shingle) formed between a small island and the mainland
- may be covered at high tide
43
stabilising depositional landforms
- sand/shingle, loose/unstable sediment, easily eroded/transported
- sand dunes develop where sand is trapped by debris towards back of beach
- vegetation stabilises dunes due to plant succession
44
plant succession
- sand dunes/salt marshes colonised by plants
- first by pioneer species
- modify the environment by binding sand/soil with roots and adding nutrients when they die/decay
- plants with leaf cover help sand/mud in dunes and salt marshes to retain moisture
- changes allow other species to colonise, provide shade/improve soil
- different species colonise until it becomes stable
- final community is the climatic climax community (adjusted to climatic conditions of the area)
45
dune successional development
- embryo dunes first to develop
- grow into bigger fore dunes
- initially yellow dunes
- darken to grey dunes as decaying plants add humus
- depressions between dunes develop into dune slacks (damper areas)
- finally woodland (mature dunes)
46
salt marsh successional development
- salt-tolerant plants (e.g. eelgrass) colonise and stabilise mud flats as they develop
- halophytes (salt-tolerant species) e.g. glasswort/cordgrass slow down tidal flow and trap more mud/silt
- surface becomes drier as sediment accumulates and different plants colonise e.g. meadow grass
- creeks divide up the salt marsh
47
salt marshes
- areas of flat, silty sediments
- accumulate around estuaries or lagoons
- develop in sheltered areas of deposition, where salt and fresh water meet, and where there are no strong tides/currents
- covered at high tide
- exposed at low tide
48
sediment cells
- coastline of England/Wales divided up into 11 major cells
- act as systems
- sources, transfers, sinks
- sediment budget = amount of sediment available in a cell
- dynamic equilibrium
- positive feedback: sediment budget falls, waves continue to transport sediment, sea has surplus energy, erosion increases
- negative feedback: sediment budget increases, more deposition, sea corrects itself as it can only carry so much, any surplus deposited
49
cuspate foreland
- triangular-shaped headland
- extends out from main coastline
- coast exposed to LSD from opposite directions
- sediment deposited where the two meet, builds up
- vegetation grows and stabilises the landform
- e.g. Dungeness, Kent
50
sub-aerial processes
- weathering (gradual breakdown of rock in situ)
- mass movement (downward movement of material under the influence of gravity)
51
mechanical weathering
- freeze-thaw: water enters cracks/joints, freezes, expands, widens cracks
- salt-weathering: salt water evaporates, crystals left behind, they grow and crack the rock
- wetting and drying: rocks expand when wet, contract as they dry, crack and break up
52
biological weathering
- thin plant roots grow into cracks, roots grow thicker, cracks widen, rocks break
- birds and animals dig burrows into cliffs (+ marine organisms)
- water runs through decaying vegetation, becomes acidic, increased chemical weathering
53
chemical weathering
- carbonation: carbon dioxide in rainwater forms weak carbonic acid, reacts with calcium carbonate in limestone/chalk, forms calcium bicarbonate, easily dissolved
54
mass movement flows
material becomes jumbled up, includes:
- soil creep
- solifluction
- earth flows and mudflows
55
soil creep
- slowest form of movement
- almost continuous process
- very slow downhill movement of individual soil particles
- forms terracettes
56
solifluction
- downhill flow of saturated soil
- occurs mainly in tundra areas
- ground is frozen
- top layer of soil thaws in summer
- layer below remains frozen (permafrost)
- surface layer becomes saturated
- flows over frozen subsoil and rock
57
earth flows and mudflows
- increase in amount of water
- e.g. heavy rain
- reduces friction
- earth/mud flows over underlying bedrock
58
mass movement slides
material remains intact/moves 'en masse' and includes:
- rock falls
- block falls
- rock/debris slides
- slumps
59
rock falls
- strong, jointed, steep rock faces/cliffs exposed to mechanical weathering
- occur on slopes over 40°
- material bounces or falls vertically to form scree/talus at foot of slope/cliff
- talus scree slope produced
60
block falls
- large block of rock falls away from cliff as a single piece
- due to jointing of the rock
61
rock/debris slides
- increase in amount of water
- reduces friction
- causes sliding
- slabs of rock/blocks slide over underlying rocks along a slide/slip plane
62
slumps
- saturated conditions
- involves rotational movement
- moderate to steep slopes
- common where softer materials overlie more-resistant/impermeable rock
- causes rotational scars
- repeated slumping creates a terraced cliff profile
63
eustatic change
when the sea level itself rises or falls:
- ice formation/melting
- thermal expansion
64
isostatic change
when the land rises or falls, relative to the sea:
- post glacial adjustment
- isostatic subsidence and recovery
- accretion
- tectonics
65
emergent coastline
- isostatic recovery
- fall in sea level
- exposes land previously covered by the sea
- raised beaches
- fossil cliffs
- e.g. the Isle of Arran, Scotland
66
submergent coastline
- rise in sea level
- floods a previously exposed coast
- rias (flooded river valleys)
- fjords (flooded glacial valleys)
- Dalmatian coast
67
storm surge
a change in sea level caused by intense low-pressure systems, e.g. depressions and tropical cyclones, and high wind speeds
68
Integrated Coastal Zone Management (ICZM)
a strategy designed to manage complete sections of the coast, rather than individual towns or villages, by bringing together all of those involved in the development, management and use of the coast
69
Shoreline Management Plan (SMP)
a plan that takes into consideration the risks of coastal processes and attempts to identify sustainable coastal defence and management options
70
Cost Benefit Analysis (CBA)
a process by which the financial, social and environmental costs are weighed up against the benefits of a proposal in terms of social outcomes as well as in terms of profit and loss
71
Environmental Impact Assessment (EIA)
a quantitative means of estimating the environmental changes arising from a proposal
72
deforesting mangrove forests
- cleared to make room for agriculture/tourist developments/shrimp aquaculture
- loss of a natural ‘barrier' or protection
- e.g. from rising sea levels and storm surge events
73
destruction of coral reefs
- first barrier against currents/strong waves
- when destroyed, stronger than normal waves/currents reaching coast can undermine fine sediment in which mangroves grow
- prevents seedlings from taking root
- washes away nutrients essential for mangrove ecosystems
- prevents natural sediment from accumulating which would normally help maintain/increase height of island
74
dredging
- involves scooping/sucking sediment up from the seabed/a river bed
- usually for construction sand/gravel
- or to deepen a channel so that large boats can navigate it
75
adaptation
making changes to lessen the impact of flooding e.g. building sea walls/storm-surge barriers, reinstating mangrove forests
76
mitigation
making efforts to reduce the emission of greenhouse gases and so reduce the impacts of climate change
77
hard engineering
involves building structures along the coast e.g. sea walls, groynes and revetments (at the base of a cliff or on a beach)
78
groynes
- timber/rock structures built at right angles to the coast
- trap sediment being moved along coast by LSD, building up beach
- built-up beach increases tourist potential, protects land behind it
- work with natural processes
- not too expensive
- terminal groyne syndrome
- unnatural, can be unattractive
79
sea walls
- stone/concrete, at foot of cliff or top of beach, curved face to reflect waves back into sea
- effective prevention of erosion
- promenade for people to walk along
- reflect wave energy rather than absorbing
- intrusive and unnatural
- very expensive to build/maintain
80
rip-rap (rock armour)
- large rocks placed at foot of cliff/top of beach, forms permeable barrier to sea, breaks up waves but allows some water to pass through
- relatively cheap and easy to build/maintain
- often used to fish from or for sunbathing
- rocks don't always fit in with local geology/can look out of place
- dangerous for people climbing on them
81
revetments
- sloping wooden/concrete/rock structures
- break up wave energy
- relatively inexpensive to build
- intrusive and very unnatural
- can need high levels of maintenance
82
offshore breakwater
- partly submerged rock barrier
- designed to break up waves before they reach the coast
- effective permeable barrier
- visually unappealing
- potential navigation hazard
83
soft engineering
designed to work with natural processes in the coastal system, in order to manage (but not necessarily prevent) erosion
84
beach nourishment
- addition of sand/pebbles to existing beach to make it higher/wider
- sediment usually dredged from nearby seabed
- relatively cheap/easy to maintain
- looks natural/blends in with existing beach
- bigger beach increases tourist potential
- needs constant maintenance (due to natural processes of erosion and LSD)
85
cliff regrading and drainage
- reduces angle of cliff to help stabilise it
- removes water to prevent landslides and slumping
- can work on clay or loose rock where other methods won't work
- cost-effective
- effectively causes cliff to retreat
- drained cliffs can dry out and lead to collapse (rock falls)
86
dune stabilisation
- marram grass planted to stabilise dunes
- areas fenced in to keep people off newly planted dunes
- maintains a natural environment
- provides important wildlife habitats
- relatively cheap and sustainable
- time consuming to plant
- people can respond negatively to being kept off certain areas
87
marsh creation
- form of managed retreat
- allows low-lying coastal areas to be flooded by the sea
- land becomes a salt marsh
- relatively cheap, involves land reverting to original state (before it was managed for agriculture)
- creates a natural defence, providing a buffer to powerful waves
- creates important wildlife habitat
- agricultural land is lost
- farmers/landowners need to be compensated
88
hold the line
involves maintaining the current position of the coastline (often using hard-engineering methods)
89
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)
90
managed retreat/strategic realignment
involves allowing the coastline to retreat but in a managed way, can involve deliberate breaching of flood banks built to protect low-quality farmland from flooding (creating salt marsh environments)
91
do nothing/no active intervention
involves letting nature take its course and allowing the sea to erode cliffs and flood low-lying land (whilst letting existing defences collapse)
