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Physical Geography > Coastal Systems and Landscapes > Flashcards

Coastal Systems and Landscapes Flashcards

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1
Q

why are coasts open systems?

A

it receives inputs from outside the system and transfers outputs away from the coast and into other systems

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2
Q

in what circumstances can coasts be considered closed systems?

A

during scientific research, coastline management planning, etc

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3
Q

what is a sediment cell?

A

a largely self contained stretch off coastline

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4
Q

how do the flows of sediment act in sediment cells?

A

in dynamic equilibrium

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5
Q

is the movement of sediment contained in sediment cells?

A

almost

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6
Q

what is dynamic equilibrium?

A

the maintenance of a balance in a natural system, despite it being in a constant state of change

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7
Q

how is the balance in dynamic equilibrium achieved?

A

by inputs and outputs constantly changing to maintain balance, and counteracting any changes imposed on the system

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8
Q

what is dynamic equilibrium in a sediment cell?

A

inputs and outputs of sediment are in a constant state of change, but remain in balance

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9
Q

how can dynamic equilibrium be upset in the long term in sediment cells?

A

by human interventions

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10
Q

how can dynamic equilibrium be upset in the short term in sediment cells?

A

by natural variations

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11
Q

when are the smaller subcells, in sediment cells, used?

A

when planning coastal management projects

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12
Q

what are positive feedback loops?

A

coastal system mechanisms which enhance changes within a system, taking it away from dynamic equilibrium

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13
Q

what are negative feedback loops?

A

mechanisms which balance change, taking the system back towards equilibrium

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14
Q

what are the 6 sediment sources?

A
  • rivers
  • cliff erosion
  • wind
  • glaciers
  • offshore
  • longshore drift
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15
Q

what are sediment budgets?

A

they use data of inputs, outputs, stores and transfers to asses the gains and losses of sediment within a sediment cell

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16
Q

what is the littoral zone?

A

the area of land between the cliffs or dunes on the coast and the offshore area that is beyond the influence of the waves

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17
Q

why is the littoral zone constantly changing?

A

short term factors like tides and storm surges, and long term factors like changes in sea level and human intervention

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18
Q

what is shore/shoreline?

A

the boundary between the sea and the land

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19
Q

what is offshore?

A

the area beyond the influence of the sea

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20
Q

what is onshore?

A

the area of land not covered by the sea, but very close to it

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21
Q

what is the primary source of energy for all natural sources?

A

the sun

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22
Q

what is the main energy source at the coast?

A

from waves which are formed offshore

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23
Q

when do waves occur?

A

when wind moves across the surface of water

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24
Q

how is a wave formed?

A

winds move across the surface of the water, causing friction drag, creating ripples and waves. Leading to a circular orbital motion of water particles in the ocean

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25
Q

what leads to a more horizontal movement of waves?

A

as the seabed becomes shallower towards the coastline, the orbit of the water particles becomes more elliptical

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26
Q

what happens when waves move more horizontally?

A

the wave height increases, but the wavelength and wave velocity both decrease

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27
Q

what does wave height increasing, but wavelength and velocity increasing cause?

A

water to back up from behind the wave until the wave breaks and surges up the beach

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28
Q

what is the swash?

A

when the wave moves up the beach

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29
Q

what is the backwash?

A

when the wave moves down the beach into the sea

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30
Q

what are the 3 factors affecting wave energy?

A
  • strength of the wind
  • duration of the wind
  • size of the fetch
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31
Q

strength of wind as a factor affecting wave energy

A

the larger the difference between two areas the stronger the winds

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32
Q

duration of the wind as a factor affecting wave energy

A

if the wave is active for longer periods of time, then the energy of the waves will build up and increase

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33
Q

size of fetch as factors affecting wave energy

A

the larger the fetch, the more powerful the waves will be

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34
Q

how are constructed waves formed?

A

formed by weather systems that operate in the open ocean

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35
Q

how are destructive waves formed?

A

localised storm events with stronger winds operating closer to the coast

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36
Q

what is the wavelength of constructive waves?

A

long wavelength

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37
Q

what is the wavelength of destructive waves?

A

short wavelength

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38
Q

what is the frequency of constructive waves?

A

6-9 per minute

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39
Q

what is the frequency of destructive waves?

A

11-16 per minute

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40
Q

what are the wave characteristics of constructive waves?

A

low waves, which surge up the beach

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41
Q

what are the wave characteristics of destructive waves?

A

high waves, which plunge onto the beach

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42
Q

what are the swash characteristics of constructive waves?

A

strong swash, weak backwash

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43
Q

what are the swash characteristics of destructive waves?

A

weak swash, strong backwash

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44
Q

what effect do constructive waves have on the beach?

A

occurs on gently sloped beaches

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45
Q

what effect do destructive waves have on the beach?

A

occurs on steeply sloped beaches

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46
Q

what time of year are constructive waves dominate?

A

summer

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47
Q

what time of year are destructive waves dominant?

A

winter

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48
Q

how can constructive waves become destructive?

A

if a storm begins

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49
Q

what does the presence of constructive waves cause?

A

deposition on the beach

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50
Q

what does deposition on the beach from constructive waves lead to?

A

the beach profile becoming steeper

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51
Q

how can destructive waves become constructive?

A

destructive waves erode the beach, reducing the beach profile and leading to the formation of constructive waves

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52
Q

what is gravity as a source of energy in coastal environments responsible for?

A

tides which occur when the gravitational pull of the sun or moon changes the water levels of the seas and oceans

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53
Q

what is the tidal range?

A

the difference in height between the tides

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54
Q

where do tidal ranges tend to be the highest?

A

in channels

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55
Q

when do the highest high tides and the lower low tides occur?

A

when the sun and the moon are in alignment

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56
Q

what are rip currents?

A

powerful underwater currents occurring in areas close to the shoreline on some beaches when plunging waves cause a buildup of water at the top of the beach

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57
Q

what forms an underwater current in rip currents?

A

the backwashed is forced under the surface due to resistance from breaking waves

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58
Q

when do rip currents occur?

A

when the sea tide pulls water through a small area

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59
Q

where do high energy coastlines occur?

A

in areas where there is a large fetch

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60
Q

what are the results of high energy coastlines?

A

these coastlines are often eroding as the rate of erosion exceeds the rate of deposition

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61
Q

where do low energy coastlines occur?

A

in sheltered areas where constructive waves prevail

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62
Q

what is wave refraction?

A

the process bu which waves turn and lose energy around a headland on uneven coastlines.

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63
Q

what is erosion?

A

a collaborative process which involves the removal of sediment from a coastline by different types of erosion

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64
Q

what are the 6 main processes of erosion?

A
  • corrasion
  • abrasion
  • attrition
  • hydraulic action
  • corrosion
  • wave quarrying
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65
Q

what is corrasion?

A

sand and pebbles are picked up by the sea from an offshore sediment sink or temporal store and hurled against the cliffs at high tide, causing cliffs to be eroded

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66
Q

what is abrasion?

A

the process where sediment is moved along the shoreline, causing it to be warn down overtime

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67
Q

what is attrition?

A

wave action cause rocks and pebbles to hit against each other, wearing each other down and becoming round and eventually smaller

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68
Q

what is hydraulic action?

A

as a wave crashes onto a rock or cliff face, air is forced into cracks, joints and faults. high pressure causes cracks to force apart and widen, these may implode under high pressure causing erosion

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69
Q

what is corrosion?

A

the mildly acidic seawater can cause alkaline rock to be eroded

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70
Q

what is wave quarrying?

A

when breaking waves that hit the cliff face exert a pressure up to 30 tonnes per m^2.

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71
Q

what are the 6 factors affecting coastal erosion?

A
  • waves
  • beaches
  • subaerial processes
  • rock type
  • rock faults
  • rock lithology
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72
Q

how do beaches affect erosion?

A

if there is a beach in-front of a cliff then this will absorb wave energy and thus reduce the effects of erosion

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73
Q

how do subaerial processes affects erosion?

A

weathering and mass movement weaken cliffs

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74
Q

how does rock type affect erosion?

A

sedimentary rocks are made up of cemented sediment particles and are therefore vulnerable to erosion, where as rocks with interlocking crystals are resistant to erosion

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75
Q

how do rock faults affect erosion?

A

fissures, cracks and joints are all types of weaknesses within the rock, so the more there are, the quicker erosion of rock will occur, also increase rock face surface area, promoting erosion

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76
Q

how does rock lithology affect erosion?

A

the type and condition of rocks creation directly affects its vulnerability to erosion

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77
Q

what is coastal transportation responsible for?

A

transferring sediment within a sediment cell and between other sediment cells

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78
Q

what are the four main processes of transportation?

A
  • traction
  • saltation
  • suspension
  • solution
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79
Q

what is traction?

A

large, heavy sediment rolls along the sea bed pushed by currents

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80
Q

what is saltation?

A

smaller sediment bounces along the sea bed, being pushed by currents

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81
Q

what is suspension?

A

small sediment is carried within the flow of water

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82
Q

what is solution?

A

dissolved material is carried within the water, potentially in a chemical form

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83
Q

how does longshore drift use transportation to move sediment along the beach?

A
  • waves hit the beach at direction of prevailing wind
  • waves push sediment up the beach in swash
  • gravity carries sediment down the beach in backwash
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84
Q

when does deposition occur?

A

when sediment becomes too heavy for the water to carry, or if the wave loses energy

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85
Q

what is gravity settling?

A

the waters velocity decreases so sediment begins to be deposited

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86
Q

what is flocculation?

A

clay particles clump together due to chemical attraction and then sink due to their high density

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87
Q

what is weathering?

A

the breakdown of rocks over time, leading to the transfer of material into the littoral zone, where it becomes an input to sediment cells

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88
Q

positive feedback effect on weathering?

A

if rate of removal of weathered rock from base of cliff is higher than the rate of weathering, then it will increase the area of exposed rock

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89
Q

negative feedback effect on weathering?

A

if removal of sediment rock from base of cliff is slower than the rate of weathering, it will lead to build up of debris at the base of the cliff, reducing the exposed cliff area and reducing rates of weathering

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90
Q

what is mechanical weathering?

A

the breakdown of rocks due to exertion of physical forces without any chemical changes taking place

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91
Q

what are the 3 types of mechanical weathering?

A
  • freeze thaw
  • salt crystallisation
  • wetting and drying
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92
Q

what is chemical weathering?

A

the breakdown of rocks through chemical reactions

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93
Q

what are the 3 types of chemical weathering?

A
  • carbonation
  • oxidation
  • solution
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94
Q

what is freeze thaw weathering?

A

water enters cracks in rocks and then the water freezes overnight in winter, this expands by 10%in volume, creating pressure and cracks. the makes the cliff weaker and vulnerable to erosion

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95
Q

what is salt crystallisation?

A

as seawater evaporates, salt is left behind and salt crystals grow, erecting pressure on the rock, widening cracks. salt can corrode ferrous rock due to chemical reactions

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96
Q

what is wetting and drying?

A

rocks expand when wet and the contract when drying. this frequent cycle can cause rocks and cliffs to break up.

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97
Q

why are rivers sediment sources?

A

sediment may be deposited in estuaries which are brackish (salty) areas where rivers flow into the sea

98
Q

why is cliff erosion a sediment source?

A

cliffs erode easily, providing a significant sediment input

99
Q

why is wind a sediment source?

A

wind is a coastal energy source and sediment transport by winds which provide sediment inputs

100
Q

why are glaciers sediment sources?

A

in some coastal systems glaciers flow directly into the ocean depositing sediment that was stored in ice, occurring when glaciers calve

101
Q

why is offshore a sediment source?

A

sediment is transferred to the coastal zone when waves, tides and currents erode offshore sediment sinks. the sediment is transported onto the beach, helping to build up the beach

102
Q

why is longshore drift a sediment source?

A

sediment moves along beach with prevailing wind, which alter the direction of waves, this allows sediment to move along the coastline. the swash moves sediment up and backwash moves it back down the beach

103
Q

what is biological weathering?

A

the breakdown of rocks by organic activity

104
Q

what are the 5 types of biological weathering?

A
  • plant roots
  • birds
  • rock boring
  • seaweed acids
  • decaying vegetation
105
Q

what is carbonation?

A

rainwater absorbs CO^2 to. create a weak carbonic acid which reacts with calcium carbonate in rocks to form calcium bicarbonate which can be easily dissolved, causing erosion

106
Q

what is oxidation?

A

when minerals become exposed to the air through cracks and fissures, the mineral becomes oxidised, increasing volume, causing rocks to crumble

107
Q

what is solution?

A

when rock minerals are dissolved

108
Q

what are plant roots in biological weathering?

A

roots of plants growing into the cracks of rocks, which exerts pressure, eventually splitting the rock

109
Q

what are birds in biological weathering?

A

some birds such as puffins dig burrows into cliffs, weakening them and making erosion more likely

110
Q

what is rock borrowing in biological weathering?

A

many species of clams secrete chemicals that dissolve rocks and piddocks may burrow into the rock face

111
Q

what is seaweed acids in biological weathering?

A

some seaweeds contain pockets of of sulphuric acid, which if hit against a rock or cliff face, the acid will dissolve some of the rocks minerals

112
Q

what is decaying vegetation in biological weathering?

A

water that flows through decaying vegetation and then over coastal areas, will be acidic, thus causing chemical weathering

113
Q

what is mass movement?

A

the movement of material down a slope under the influence of gravity

114
Q

what 4 main areas can mass movement be categorised in too?

A
  • creeps
  • flows
  • slides
  • falls
115
Q

what are the 7 types of mass movement?

A
  • soil creep
  • solifluction
  • mudflows
  • rockfall
  • landslide
  • landslip or slump
  • runoff
116
Q

what is soil creep in mass movement?

A

particles rise and fall due to wetting and freezing and this causes soil to move down the slope. leads to the formation of shallow terracettes

117
Q

what is solifluction in mass movement?

A

as the top layers thaw during summer the surface layers flow over the frozen layers, forming solifluction lobes

118
Q

what are mudflows in mass movement?

A

an increase the water content of soil can reduce friction , leading to earth and mud flow. water can get trapped within the rock increasing pore water pressure, weakening the slope

119
Q

what are rockfalls in mass movement?

A

occurs on sloped cliffs when exposed to chemical weathering

120
Q

what are landslides in mass movement?

A

heavy rainfall leads to water between joints and bedding planes in cliffs which can reduce friction and lead to a landslide.

121
Q

what are landslip and slumps in mass movement?

A

a build up in pore water pressure leads to the land collapsing under its own weight

122
Q

what is runoff in mass movement?

A

as the water in the form of overland flow may erode the cliff face and coastal area or pickup sediment

123
Q

in what environment are steep cliffs most commonly found?

A

in high energy environments

124
Q

where are steep cliffs most common?

A

where the rock is strong and fairly resistant to erosion

125
Q

where are gentle cliffs most commonly found?

A

in areas with weaker rocks which are less resistant to erosion and are prone to slumping

126
Q

in what environment are gentle cliffs most commonly found?

A

in low energy environments

127
Q

what will lead to the formation of gentle cliffs?

A

low energy waves, a short fetch and a large beach

128
Q

what will lead to the formation of steep cliffs?

A

sedimentary rocks that have vertical strata are more resistant to erosion. also an absence of a beach, long fetch and high energy waves

129
Q

what is the rate of retreat dependant on?

A

the relative importance of marine factors and terrestrial factors

130
Q

which cliffs are most likely to retreat?

A

those made of unconsolidated rock and sands

131
Q

what landform is a beach?

A

depositional landform

132
Q

how is a beach created?

A

when sediment is deposited near the coastline when waves lose their energy

133
Q

when does beach accretion occur?

A

when the beach is being built up by constructive waves, usually in summer

134
Q

when does beach excavation occur?

A

in winter when destructive waves remove sediment from the beach

135
Q

what is swash aligned?

A

wave crests approach perpendicular to coast so there is limited longshore drift

136
Q

what is drift alignment?

A

waves approach at a significant angle

137
Q

what are berms?

A

ridges which mark where the high tide line is at different times of year

138
Q

what are cusps?

A

small curved dips in the beach where the swash comes in, and are slightly lower than the rest of the beach, creating undulations

139
Q

what are runnels?

A

smaller ridges that are often found in smooth wet sand further towards the sea, caused by the tides

140
Q

where is larger sediment found?

A

towards the top of the beach, where it has been left from winter storms

141
Q

beach profiles and sediment types are dependant on what?

A

distance from the shoreline

142
Q

what are spits?

A

a long narrow strip of land which is formed when longshore drift causes the beach to extend out to sea, usually due to change in direction of the coastline

143
Q

what can the sediment projection from spits create?

A

a salt marsh, due to the sheltered, saline environment where water flow speed is lower, allowing deposition of finer sediments to occur

144
Q

what does the length of a spit depend on?

A

any changing currents of rivers, which will prevent sediment from being deposited

145
Q

what can cause the end of a spit to curve?

A

a change in wind or wave direction

146
Q

what is a compound spit?

A

when spits have multiple recurved tips

147
Q

what is a double spit?

A

the spits from opposites sides of a bay reach out towards each other

148
Q

when does a barrier beach occur?

A

when a beach for spit extends across a bay to join two headlands

149
Q

how does a barrier beach lead to the formation of a brackish lagoon?

A

water gets trapped behind it, and the brackish lagoon is separated from the sea

150
Q

how have some barrier beaches formed due to rising sea levels after the last glacial period?

A

meltwater from glaciers deposited sediment in the coastal zone

151
Q

when does a barrier beach become a barrier island?

A

if a barrier beach becomes separated from the mainland

152
Q

where are barrier islands most common?

A

in areas with low tidal ranges and can be very large

153
Q

what is a tombolo?

A

a bar or beach that connects the mainland to an offshore island

154
Q

what is a tombolo formed due to?

A

wave refraction off the coastal island reducing wave velocity

155
Q

how are sand dunes formed?

A

when sand deposited by longshore drift is moved up the beach by the wind

156
Q

how are embryo dunes formed?

A
  • sand trapped by driftwood or berms is colonised by plants and grass
  • the vegetation stabilizes the sand and encourages more sand to accumulate there
157
Q

how are mature dunes formed?

A

overtime, the oldest dune migrate inland as newer embryo dunes are formed (can be up to 10m high)

158
Q

where do mudflats and saltmarshes form?

A

sheltered, low energy environments

159
Q

how do mudflats develop?

A

as silt and mud are deposited by the river or the tide

160
Q

how are mudflats colonised?

A

by vegetation that can survive the high salt levels and long periods of submergence by the tide

161
Q

how are saltmarshes formed?

A

plants trap more mud and silt in a mudflat, and grudually they build up to a saltmarsh that remains exposed for longer and longer between tides

162
Q

what causes channels in the surface of mudflats and saltmarshes?

A

erosion by tidal currents

163
Q

what is eustatic sea-level change caused by?

A

a change in the volume of water in the sea or a change in the shape of the ocean basins

164
Q

are the effects of eustatic sea-level change local or global?

A

global

165
Q

what are the main causes of eustatic sea-level change

A
  • changes in climate change

- tectonic movements of the earths crust and alter the shape of ocean basins

166
Q

how does changes in climate change affect eustatic sea-level change?

A
  • an increase in temperature causes melting of the ice sheets, which increases sea level
  • causes water to expand, increasing sea level more
167
Q

what is isostatic sea-level change caused by?

A

vertical movements of the land relative to the sea

-any downward movement of the land causes sea level to rise locally, while up lift of land causes sea level to fall

168
Q

are the effects of isostatic sea level change local or global?

A

local

169
Q

what are the main causes of isostatic sea level change?

A
  • uplift or depression of the earth’s crust due to accumulation or melting of ice sheets
  • subsidence of land due to shrinkage after abstraction of groundwater
  • tectonic processes
170
Q

what causes the sea level to vary daily?

A

the tidal cycle

171
Q

what causes sea level to rise temporarily?

A
  • onshore winds

- low atmospheric systems

172
Q

why has global sea-level changed over a long period of time?

A

as temperatures start to increases, ice sheets melted and sea level rose rapidly (it reached its present level around 4000 years ago) and sea-level now fluctuates

173
Q

what is global warming?

A

global sea temperatures increasing rapidly

174
Q

what is global warming a result of?

A

human activities

-e.g. deforestation and burning fossil fuels

175
Q

how do human activities lead to global warming?

A

the activities increase the concentration of greenhouse gases in the atmosphere. greenhouse gases absorb outgoing long wave radiation, so less is lost to space. as their concentration increases, more energy is trapped and the planet warms up

176
Q

why are increases in temperature likely to lead to increases in sea level?

A

melting of ice sheets and thermal expansion of water in oceans

177
Q

how many mm is global sea level rising a year?

A

2mm

178
Q

if greenhouse gas emissions remain high, how much is the sea level predicted to increase in mm by 2100?

A

8-16mm

179
Q

why are storms likely to become more frequent and more intense?

A

due to changes in ocean circulation and wind patterns

180
Q

why will continued sea-level rise have major impacts on coastal areas?

A
  • more frequent and severe coastal flooding
  • submergence of low lying islands
  • changes in the coastline
  • contamination of water sources and farmland
181
Q

how are raised beaches formed?

A

when the fall in sea level leaves beaches above the high tide mark

182
Q

where are rias formed?

A

where river valleys are partially submerged

183
Q

what do rias look like?

A

they’re wide and deep at their mouth, becoming narrower and shallower the further inland they reach

184
Q

what are rias?

A

drowned river valleys

185
Q

what are fjords?

A

drowned glacial valleys

186
Q

what do fjords look like?

A

they are relatively straight and narrow, with very steep sides. They have a shallow mouth and very deep further inland

187
Q

why do fjords have a shallow mouth?

A

caused by a raised bit of ground (called the threshold) formed by deposition of material by the glacier

188
Q

how are dalmation coastlines formed?

A

in areas where valleys lie parallel to the coast an increase in sea level can cause them

189
Q

individual landforms combine to form what?

A

landscapes

190
Q

what is the aim of coastal management?

A

protect homes, businesses and the environment from erosion and flooding

191
Q

what is the location of coastal management dependent on?

A

cost-benefit analysis

-protect large settlements and industrial siyes

192
Q

what are the 4 options for coastal management?

A
  • hold the line
  • advance the line
  • do nothing
  • managed realignement
193
Q

what is hold the line in coastal management?

A

maintaining the existing coastal defences

194
Q

what is advance the line in coastal management?

A

build new coastal defences further out to sea than the existing line of defence

195
Q

what is do nothing in coastal management?

A

build no coastal defences, and deal with erosion and flooding as it happens

196
Q

what is managed realignment in coastal management?

A

allow the shoreline to move, but manage retreat so it causes least damage

197
Q

what is hard engineering?

A

built structures

198
Q

how does a sea wall work?

A
  • the wall reflects waves back out to the sea, preventing erosion of the coast
  • a barrier to protect from flooding
199
Q

what are the disadvantages of sea walls?

A
  • expensive to build and maintain

- creates a strong backwash which erodes under the sea wall

200
Q

how does revetment work?

A

waves break against the revetments, which absorb the wave energy and so prevent cliff erosion

201
Q

what is a revetment?

A

slanted structures at the foot of cliffs, made from concrete, wood or rocks

202
Q

what are gabions?

A

rock-filled cages

-wall of gabions usually at the foot of cliffs

203
Q

how do gabions work?

A

they absorb wave energy and so reduce erosion

204
Q

what are the disadvantages of revetments?

A
  • expensive to build

- they create a strong backwash

205
Q

what are the advantages of revetments?

A

relatively cheap to maintain

206
Q

are gabions expensive?

A

no, they are cheap

207
Q

what is a disadvantage of gabions?

A

they are ugly

208
Q

what are ripraps?

A

boulders piled up along the coast

209
Q

how do ripraps work?

A

the boulders absorb wave energy and so reduce erosion

210
Q

are ripraps cheap?

A

fairly cheap

211
Q

what is a disadvantage of ripraps?

A

they can shift in storms

212
Q

what are groynes?

A

fences built at right angles to the coast

213
Q

how do groynes work?

A

they trap beach material transported by longshore drift. This creates wider beaches which slow the waves and gives greater protection from flooding and erosion

214
Q

are groynes cheap?

A

quite cheap

215
Q

whats a disadvantage of groynes?

A

they starve downdrift beaches of sand. Thinner beaches don’t protect the coast as well, leading to greater erosion and flooding

216
Q

what are breakwaters?

A

usually concrete blocks or boulders deposited by the coast

217
Q

how do breakwaters work?

A

they force waves to break offshore. The waves energy and erosive power are reduced before they reach the shore above

218
Q

what are earth banks?

A

mound of earth

219
Q

what are the disadvanteages of breakwaters?

A
  • expensive

- can be damaged in storms

220
Q

how do earth banks work?

A

they act as a barrier to protect flooding

221
Q

what are the disadvantages of earth banks?

A
  • quite expensive

- can be eroded

222
Q

what are tidal barriers?

A

built across river estuaries and contain retractable flood gates

223
Q

how do tidal barriers work?

A

they have retractable floodgates which can be raised to prevent flooding from from storm surges

224
Q

what are the disadvantages of tidal barriers?

A

-VERY expensive

225
Q

what are tidal barrages?

A

dams built across river estuaries. Their main purpose is to generate electricty

226
Q

how do tidal barrages work?

A

water is trapped behind the dam at high tide. Controlled release of water through turbines in the dam at low tide generates electricity. They also prevent flooding from storm surges

227
Q

what are the disadvantages of tidal barrages?

A
  • VERY expensive

- they disrupt sediment flow which may cause increased erosion elsewhere in the estuary

228
Q

what is soft engineering?

A

involves coaxing natural processes along

229
Q

what is beach nourishment?

A

where sand and shingle are added to beaches from elsewhere

230
Q

what does beach nourishment do?

A

it creates wide beaches, which reduce erosion of cliffs more than thin beaches

231
Q

what is beach stabilisation?

A

reducing the slope angle and planting vegetation, or by sticking stakes and old tree trunks in the beach to stabilize the sand, also creates wider beaches

232
Q

what is dune regeneration?

A

where sand dunes are created or restored by either nourishment or stabilisation of the sand

233
Q

what does dune regeneration do?

A

dunes provide a barrier between land and sea, absorbing wave energy and preventing flooding and erosion

234
Q

why is land use management important for dune regeneration?

A

the vegetation needed to stabilise the dune can easily be trampled and destroyed, leaving the dune vulnerable to erosion

235
Q

what is coastal realignment (managed retreat)?

A

involves breaching an existing defence and aloowing the sea to flood the land behind

236
Q

is soft or hard engineering more sustainable?

A

soft engineering

237
Q

why is soft engineering more sustainable?

A

lower environmental impact and economic cost

238
Q

what are the 2 important ideas involved in deciding how to manage coastal areas sustainably?

A
  • shoreline management plans

- integrated coastal zone management

239
Q

what are shoreline management plans?

A

a plan is devised for how to manage different areas with the aim of protecting important sites without causing problems elsewhere in the sediment cell

240
Q

what does integrated coastal zone management do?

A

considers all elements of the coastal system when coming up with a management strategy. It aims to protect the coastal zone in a relatively natural state, while allowing people to use it and develop it in different ways

Physical Geography (6 decks)

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