1
Q
What are the 7 properties of constructive waves
A
1.smaller in height-low wave height, long wavelength
2.less energy
3.weak backwash
4.little erosion, depositional
5.strong swash which pushes material up the beach
6.light moderate winds
7.low frequency
2
Q
8 properties of destructive waves
A
1.strong backwash, undertow
2.weak swash
3.high wave height, short wavelength, larger in height
4.more energy
5.scours the beach, pulling sand and shingle down beach
6.little beach building, erosional
7.strong winds
8.high frequency
3
Q
What is erosion
A
Wearing of rock away along the coastline-moving force causes this, destructive waves are responsible for this as they have more power,
4
Q
4 types of coastal erosion
A
Hydraulic action, abrasion, attrition, solution
5
Q
What is hydraulic action
A
hydraulic action=sheer power of the waves as smash against the cliff, air is trapped in cracks of rock and cause it to break apart due to compressed air creating pressure, rock is disintegrated
6
Q
What is abrasion
A
When pebbles/sediment grind along a rock platform, over time rock becomes smooth
7
Q
What is attrition
A
Rocks carried by sea knock against each other, become smaller and rounded
8
Q
What is solution
A
Sea water dissolves certain types of rock eg chalk and limestone
9
Q
What is the odd one out between the four types of coastal erosion
A
Attrition is the odd one out as it does not erode the cliff, it just erodes sediment compared to the others
10
Q
What is the top of the cliff called and it’s role
A
Cliff face=where most of the weathering takes place
11
Q
What is the bottom of the cliff called and it’s role
A
Almost all coastal erosion takes place at the cliff foot
12
Q
What are the two types of winds that hit the uk
A
1.prevailing wind-south westerly, from the Caribbean, 5km fetch- creates strong winds as it blows over ocean, meaning it experiences less friction
2.arctic winds-northerly, also won’t experience as much friction
13
Q
why are high energy coastlines and 5 features of them
A
powerful waves for much of the year, rates of erosion exceeds rate of deposition (earosional features), strongest towards the west coast of ireland, fetch is long, cliffs form, stack, stump, arches, strongest in cornwall, devon (southwest england), across atlantic ocean, lack of friction, large amount of energy built up, winds from north west
14
Q
5 features of a low energy coastline
A
less powerful waves, coast is sheltered from large waves, rates of deposition exceeds rate of erosion (depositional features), examples include west wales coast as ireland shelters it, spits, bars (depositional)
15
Q
examples of high energy coastlines
A
northern scotland (from arctic winds), north west scotland-the hebrides
16
Q
examples of low energy coastlines
A
southern kent and sussex
17
Q
what are discordant coastlines
A
bands of hard /resistant rock and soft/less resistant rock forming headlanfs and vays, layers of geology perpendicular to coastline
18
Q
process of discordant coastline
A
1.wave cut notch forms in cliff foot
2.then erodes into a cave
3.cliff face unable to support itself therefore it moves back after rock fall
4.new cliff face forms
5.continues into wave cut platform
6.headland erodes from cave to arch to stack to stump
19
Q
why are waves hitting headlands the most
A
as waves get closer to headland, it begins to refracr as forces of waves focused in headland due to wave refraction due to frictional drag as the waves refract around the headland
20
Q
what are concordant coastlines
A
bands of soft/less resistant and hard/resistant rock run parallel to the coast, breaches in hard rock occur in fault lines, or weakenesses of the rock, creaves a cove from wave direction, an example is dorset coast and lulworth cove
21
Q
holderness coast case study
A
-flamborough head made of sedimentary, hard chalk
-prevailing winds from north sea
-made of boulder clay (unconsolidated glacial deposits, not been crushed, into layers, very weak rock creates a problem)
-5 towns-birdington, hornsea, mappleton, great cowden, witherses, easington
-spurn head/point
-has the river humber estuary
-fluvial deposits-river
-holocine
-in east yorkshire, uk
-to the south there is hull
adjacent to river humber
22
Q
birdington-holderness coast case study
A
sea wall-reflects wave energy
groynes-limits longshore drift, maintains beach
-main economy is tourism for its beach
-pier
-0 metres per year of erosion
23
Q
mappleton-holderness coast case study
A
-stone groyne that limits longshore drift, expensive, made beach wider, the bigger the beach, the more wave energy it can absorb
-rock armour to south which prevenets cliff erosion, rip rap absorbs wave energy and reduces cliff foot erosion movement, only extends 100m south of groyne which is precise to the area protected
-sloped cliffs/regraded, less vertical, limits mass movement
24
Q
easington- holderness coast case study
A
-gas terminal to receive north sea gas, highly protected
-riprap/rock armour absorbs wave energy and cliff foot protects
-regraded cliff
25
What is longshore drift
Movement of sediment along coastline
26
5 features of long shore drift
Direction of movement is to the right, swash and backwash, backwash is at a right angle to the beach due to gravity as there is no kinetic energy left,
27
What type of coastal defence can stop longshore drift
Groynes, slow and limit ld
28
5 coastal features formed from deposition
1.spit
2.baymouth bar
3.double spits
4.tombolo
5.cuspate foreland
29
What is a spit and what is its features
Extended stretch of beach material, stretching out to sea, joined to main land at one end
Salt marsh is formed, has a proximal end and distal end which is near the estuary, has longshore drift, two winds- prevailing wind, and second most dominant wind and fetch,
Hooked spit due to second most dominant wind amd fetch, estuary is where the river flows into the sea, the flow of the river/current prevents the spit extending across the estuary,
Used as a defensive site, light houses, golf course, caravan parks, very prone to flooding and coastal erosion
30
What is a baymouth bar and how does it form
Similar to spit, but extends to both ends, can be caused by a storm wave which picks and deposits an offshore bar on the coastline
31
What is a double spit and how is it formed
Two spots growing at different or opposite directions at the mouth of a harbour,
a result of two dominant wind directions, do not meet due to rivers current, for Weymouth , the Isle of Wight funnels winds
32
What is a tombolo and how is it formed
Where an island is linked to the mainland by a beach, forms by longshore drift, overtime beach is extended, eg Burgh island in south Devon use sea tractors
33
What is a cuspate foreland and how is it formed
Triangular depositional feature, Can build nuclear power stations, formed due to longshore drift, dungeness in Kent eg
34
what is littoral zone
wider coastal zone including adjacent land areas and the shallow parts of the sea just offshore-exposed to air at low tide and underwater high tide
35
4 parts of the littoral zone
1. backshore= usually above influence of waves, above tide line, not covered on an average day tide
2.foreshore= intertidal surf zone, where backwash and swash take place
3.nearshore=breaker zone, breaking waves occur (when waves spill over)
4.offshore=beyond the influence of waves, open sea
36
what is the breakpoint par
zone of breaking waves between nearshore and offshore
37
3 types of tides
max spring tide/rare, high tide and low tide
38
what is tides
cuased by gravitational pull of moon or sun, long period waves that appear to move through ocean, water bulging into ocean,
39
high tide
sea surface reaches highest point
40
low tide
sea surface at lowest point
41
tidal range
difference between high and low tide
42
how many tides occur in a day
2 hgih and 2 low a day based on lunar day, at different times everyday-need tide map and timetable
43
what are spring tides
highest high tides-due to moon and sun alignment, two a month
44
what are neap tides
lowest low tides, two a month
45
problems with spring tide
when spring tides occur simultaenously as major storm systems, lead to severe problems, storm tide is pushing in land faster, 1953 storms of east anglia and holland- worst flooding since records began, 2 metres higher than predicted, storm surge, arctic winds push water southwards, funneled narrower and narrower so water height and keeps risiing, very low line/low land, therefore flooding cannot be intercepted
46
4 types of marine transport
1.suspension=lighter sediment suspended in water, clay particles (light)
2.traction=rolling or dragging of large grains along a river bed, pebbles
3.saltation=smaller sediment bounces along the sea bed pushed by currents
4=when weak carbonic acid in seawater dissolves and breaks down, limestone is most susceptible
47
What are the three types of rock and examples of them
1.sedimentary=strata-limestone, chalk, limestone, consolidated
2. igneous=cooled lava-granite, basalt-95% of earths crust
3.metamorphic=changed by pressure and or heat- shale into slate, sandstone into quartzite, limestone into marble
48
What is the rock cycle
49
What is the relation between geology and location
Location of igneous and metamorphic is in upland areas/topography as it is more resistant to erosion
50
Resistant rock coastlines-6 characteristics
1.south west England-Cornwall
2.igneous-basalt and granite
3.sedimentary-sandstone (old red)
4.metamorphic-slate and schists
5.can withstand prevailing wing and long fetch
6.heavily consolidated sedimentary-heavily resistant
51
Coastal plain landscape 5 characteristics
1.eastern and southern uk
2.weaker and younger geology
3.chalk, clay, sandstone
4.deposition> erosion as it is a low energy coastline
5.coastal plain-area if low and flat relief-low lying sandy beaches
52
4 properties of low energy coastlines
Less powerful waves, deposition is stronger than erosion, stretches of uk coast which are chefs and spits and cuspate foreland
53
4 properties of high energy coastlines
Powerful waves, high erosion, erosion is stronger than deposition, Atlantic coastline, headland, cliff, wave cut platforms
54
what is dipping
angle at which the rocks strata lies which can be horizontal vertical, dipping to or away from the sea
55
what are the four types of dipping
horizontal,landward, seaward but at a low angle and seaward at a high angle
56
what is horizontal dipping
vertical or near vertical with notches showing weathering and small scale mass movement of jointed strata and steep slope
57
what is landward dipping
dipping away from sea, most stable, steep profile, 70-80*, downward slope gravitational force pulls loosened back into place
58
what is low angle seaward dipping
steep profile, less than 45 degrees, creates areas of overhanging rock which are vulnerable to rock fall, frequent small scale mass movement of weathered material, overhand is unsustainable
59
what is high seaward dipping
more than 45*, vertical cracks or joints are opened by weathering and pressure release, significant erosion, usually granite which is common in cornwall and erosive due to vertical joints and seaward dip, subaerial process, bedding planes between are weakly bonded and readily loosened
60
What affects the rate of erosion
1.coastal recession= how much the coast is being warn away
2-lithology or rock type, measures now resistant rocks and minerals are, igneous is high and metamorphic is also
61
How is rock resistance measured
Mohs hardness scale, 1 to 10, 10 being the hardest eg diamonds
62
Features of igneous rock which makes it resistant
Granite and basalt, erosion is very slow, crystalline (individual crystals which interlock when cooled), incredibly hard, few joint and bedding planes eg few lines of weakness
63
Features of metamorphic rock which makes it resistant
Slate, schist, slow to erode, crystalline, folded and fractured due to pressure, therefore some limes of weakness occur
64
Features of sedimentary rock which makes it resistant
Sandstone, limestone, chalk,shale, moderate to erode or fast, has bedding planes and joints, slightly weaker, younger is weaker than leer and the lower the more resistant
65
Exceptions to coastal recession
1. Oldest sandstone (sedimentary), very resistant to erosion, recently erupted colonic lava- volcaniclastic rocks
2. Unsoldiated sediment= Sand, gravel, clay, slit which hasn’t been compacted to sedimentary- loose and easily eroded, boulder clay from glacial deposits- last ice age from 10 years ago
3. Geological structure= land ward dipping, horizontal strata, seawar dripping,
4. Other factors such as prevailing winds and it’s proximity for the fetch, coastal vegetation and human factors
66
How does coastal vegetation affect rate of erosion
- reduce coastal erosion
-protects from erosion
- sand dunes and salt marshes
-Vegetation stabilises sediment as the roots bind sediment together which reduces wind speed
-Xerophytes are in dry condition, Adam grass, retains small water on sand dunes
-Halophytes tolerate saltwater, submerge as high tide and spray waves stop coastal succession
67
What is the role of coastal vegetation
-stabilises depositional landforms by holding them together, most depositional landforms are made of sand or shingle , loose, unconsolidated material that can be easily eroded or transported, roots bind to sediment so it is harder to erode, plants protect sediment from wind erosion, reduce wind speed due to friction
68
Are coastlines a good habitat for plants
No it is a hostile environment meaning it needs to be wind resistant due to strong winds from fetch, salt in water will kill plants, drought tolerant as it is dry
69
What are sand dunes and how are they formed
FormEd by aeolian action/winds, sand is transported through saltation (bounces along), larger material is moved by creep (rounding sand surface), finest material by suspension (carried by silt), eg saltmarshes, xerophytes and hydrophytes
70
Sand dunes from smallest to largest and their trends
Embryo dunes, fore dune, yellow dune, grey dune, dune slack and mature dune
The younger the more hostile, the less stable, the less plants less biodiversity and vice versa
71
Features of embryo dunes
-grows sea rocket and sea couch grass which are early colonisers and pioneer species
-tolerant so they can grow very close to sea
-can survive regular immersion in salt water for example in king tides, spring tides and storms
-can deal with a lack of nutrients and alkaline conditions
-can also tolerate sand movement
72
Features of fore dune
-grows marram grass
-long , fibrous, matted roots
-deep rooted,2m
-roots grow fast and deep to find water,
Concave shape to trap water and help to survive
-marram grass outcompetes sea rocket due to longer roots
73
What is the relation between the age of the dunes and its survival in hostile environmentsx
As the dunes age, the more soul builds up, making less hostile, which encourages coastal accreditation, the further away from sea, more likely to occur on low energy coastline
74
What is passmore succession and how does it occur
-begins with halophytic plants growing in salty bare sand
-trap more sand which leads to embryo dunes
-embryo dunes alter the environment conditions allowing xerophytic plants to flourish
-success continues and dunes gradually become fixed and a wider range of plant species can become established = sequential development
75
What is the land use of sand dunes
-sights of special scientific interest
-golf specifically golf link courses
76
How is a salt marsh succession formed
Common behind a spit, as mud and silt are deposited along a sheltered or protected part of the coastline, rates of deposition is higher than transportation due to lack of energy in waves
77
What is accretion
Grotwth by deposition of suspended particles during flooding or accumulation of plant material (roots and decomposed material)
78
Increased sedimentation v decreased sedimentation
-increased= less biomass or plants, faster flow, more turbulence, lower effective settling velocity
-decreased=high biomass or plants, slower flow, less turbulence, higher effective settling velocity
79
5 types of plants found in saltmarshes
1.seacord grass= withstand sedimentation as a pioneer species
2.eel grass=submerged for 11 hrs at once, before established, roots reduce removal of sediment as tide goes out as a halophyte
3.sea Asher=overtime as saltmarshes develops establishment stage, other plants are able to colonise, attracts pollinating insects
4.red fescue grass=climax vegetation
5.sea thrift = when it is more stable, it grows as a flowering plant
80
4 parts of zonation
1. Tidal inlet
2.low marsh-cordgrass
3.high marsh-sea lavender and sea asher
4. Marsh upland-oaks and shrubs
-increased soil fertility. Reduced salinity and reduced seawater flooding
81
What are mangroves and their adaptations
Adapated to survive in salty environment, pneumatophore roots grown above sea level, actors as snorkels, for oxygen uptake, specialised aerial roots allow oxygen to be absorbed from air, for respiration, vital for root health in oxygen deprived soil
82
coastal conflicts-winners or losers
winners are people who benefit economically socially and environmentally while losers are likely to lose homes, jobs, forced to move, sea concreted over-environmentally negative , both stakeholders involved
83
natural migration v squeeze beach
natural-no sea wall so when eroding landward, the sand dunes migrate landward
squeeze-with sea wall, erodes landward, area is squeezed therefore it prevents migration
84
what affect does sea walls have on saltmarshes
can destroy salt marsh eg essex’s have been eroded by 60% in the last 30 years
85
solution to black water estuary salt marsh conflict
-in 2000 the essex wildlife trust bought a farm on the estuary which was threatened by flooding and erosion and did realignment=4000 hectare with 5 breaches in the sea wall to allow new salt marshes to form
86
successes of coastal realignment of the black water estuary
lead to succession and accretion, farmer got market price, reduced flood risk still, water quality improved-need beds to filter out sediment, new pathway and walkways for leisure, income stream in ecotourism, and birdwatching eg dumlin, redshank, geese, and fish nurseries eg sea bass and herring, vulnerable animals which had left had now returned eg bitterns
87
what is beach morphology
the shape of a beach and its width and slope and reassures such as the birms,ridges
88
two types of beach morphology
summer profile and winter profile
89
what are the features of summer profiles
steeper, birms or ridges built up, backwash is weaker so sediment builds up due to constructive waves and lighter winds
high pressure=anti cyclone= lighter winds
90
what are the features of winter profiles
high frequency waves, berms eroded quickly, strong backwash so it transports sediment offshore due to destructive waves
91
4 methods of erosion
winds, waves, rivers and glaciers
92
what is erosion
breaking down of rock by a moving force
93
what is weathering
gradual break down of rock in situ, without a moving force, or close to the ground surface-mechanical chemical and biological
94
what is mass movement
movement of weathered material downslope due to gravity
95
what are sub aerial processes
land based processes which alter the shape of the coastline eg weathering and mass movement
96
what is weathering
gradual breakdown of rock at the earths surface through mechanical chemical and biological mechanisms, alters coastal landscape
97
what are the three types of physical or mechanical weathering
freeze thaw or frost shattering-when temp fluctuates around 0*c, water seeps cracks during warmer periods, freezes and expands at night causing the rock to fracture and break, does not happen on the southern coastline due to mild temps
exfoliation or onion peel or sunburst= peeeling of layers of rock due to thermal expansion under the heat of the sun, contraction in cool temp, occurs mostly in deserts
salt crystallisation-salt from evaporated seawater crystallises in rock pores to exert pressure and disintegration, honeycomb effect
98
what are the three types of chemical weathering
-carbonation= in limestone and chalk,co2 from air or soil mixes with rainwater to form a weak carbonic acid that dissolves calcium carbonate in rock, can be in land eg limestone pavements
-hydrolysis= reaction between rock minerals and water leading to clay formation and soluble salts
-oxidation= iron compounds in rocks reaction. with oxygen form air or water resulting in weakening and crumbling
99
what are the 3 types of biological weathering
-root wedging which is when the plant roots grow in small cracks and expand and exert pressure on the rock causing it to fracture
-organic acids= produced by plants and microorganisms to chemically break down minerals in the rock
-animal and marine burrowing eg puffins and shellfish weaken rock structures
100
what is mass movement
downward and outward movement of soil and rock under the influence of gravity, shapes coastlines in areas of soft rock or heavily fractured rock
101
what are the 4 types of mass movement
-rockfall=sudden falls of rock from cliff face triggered by physical weathering
-rotational slips or slumps=weaker rock, along concave slip plane, terraced cliff profiles
-soil creep or solifluxion= extremely slow downhill movement of soil due to gravity over long periods, stepped effect
-mudflow= rapid flow of saturated soil and weak rock due to heavy rainfall or volcanic activity
102
3 impacts of sub aerial processes on coastal development
-cliff recession
-beach nourishment
-hazards
103
what are sediment cells
moves by erosion, transport and deposition
within each cells eg sea,beach, cliff, operates within that sediment cell mostly, as a headland or estuary is usually the boundary of the cells, england and wales have 11 which have their own sub cells, the largest sediment is not transferred between cells but the smaller is through suspension eg silt
104
what is sediment budget
the amount of sediment in a cell, features build up, increased by erosion or decreased through coastal transport through negative and positive feedback to form dynamic equilibrium, needed when managing a coastal system-provide the framework
105
5 types of hard engineering
1.sea wall= can be stepped or recurved, stepped absorbs wave energy while recurved reflects wave energy
2.riprap/rock armour= prevents beach erosion by absorbing wave energy and preventing beach scouring through reflected wave energy
3.groynes= limit long shore drift, made of wood or stone, durable, wooden groynes can rot
4.offshore break waters= causes waves to break early to deposit large amounts of shingle-forms human made tombolos
5.revetments= wooden frames that absorb wave energy to allow water to slow down
6.gabions= rocks in cages
106
2 types of soft engineering
1.beach replenishment/nourishment= sediment quarried and deposited, cheap but has to be repeated
2.sand dune seeding= marram grass planted, cheaper, need to be replenished
107
4 types of coastal management
1.hold the line=coastal defences maintain coastline
2.managed realignment=Move coastline landward naturally but managed
3.advance the line=defences are built to move shore seawards
4.retreat the line=no defences
108
two types of sea level changes
1.eustatic change=sea level itself rises or falls
2.isotatic change=and rises or falls, relative to the sea
109
2 types of isotatic changes
1.tectonic activity-uplift of mountain ranges/ fold mountains, coastal land at destructive/convergent and collision plate margins, local tilting of land, eg boxing day tsunami 2004 when sea bed rose by 0.1mm, 9.3 mag, 300k killed, 15m high waves, 1600 km fault lines sloped 15m along the subduction zone
2.plate movement-tethys sea (now a seabed below the himalayas) as the indian sub continent moved north into the asian continent/collided, marine transgression and regression
110
what is marine regression
sea level drops and produces emergent coast (once covered in sea)
111
what is marine transgression
coastline is flooded and produces submergent coast
112
what is eustatic sea level change examples
-12000 years ago=ice age, ice sheets over much of the northern land surfaces, traps trillions of tonnes of water in land, decreasing the sea level
-ice on land also causes isostatic sea level changes, weighs on land and pushes land downwards eg scotland and northern england, glacial movement, land has now risen after ice age
-south east is now subsiding including southend-temp
113
what is isostatic readjustment/rebound/springback/isostasy
land has now rise after ice age during eustatic sea level change
114
Features of isostatic change
Takes longer to occur than eustatic change, land in north and west England still rising during isostatic recovery, south and east England has gradually sinking/subsiding
115
Features of emergent coastline
Once submerged but sea level has fallen or land has risen, has dead cliffs/relic cliffs and raised beach
116
Features of submerging coastline
Sea level has risen or land has subsided,
has rias-flooded river valley or v shaped valley, can be useful as ports due to deep water eg Milford haven,west Wales
Fjords-flooded glacial valleys, usually in Norway eg hardanger fjord
Croatia, dalmatians coast, concord ant coastline, parallel to coast, mountains become chain of islands, form long, narrow inlets parallel to coasts
117
what is isostatic downwarping/ isostatic subsidence/isostatic depression
ice pushes downland, due to weight of heavy load, earths crust is floating on the fluid asthenosphere/upper mantle as it is hooter and more fluid, crust deforms and sinks, 60 miles to 450 miles below the earths surface
118
bevelled cliff
gently sloping cliff-impacted by subaerial processes-not erosion, steep cliff, cliff foot erosion-former dead cliff, recently eroded at the foot eg 200 year, indicator of sea level rise
119
what is contemporary
currently happening
120
how are different places under threat from sea level changes, kiribati case study (6 different ways)
south pacific island, under threat as a result of sea level change-
1.coastal flooding and erosion=increase severity and frequency, 100 days of flooding a year by the end of the century-land loss, uprooted trees, abandoned homes
2.saltwater intrusion=contamination of drinking water, decreasing access to clean water, change in rainfall and drought patterns
3.threats to food security eg destroyed crops, decreased productivity of agricultural land, reliance on improved processed foods=unhealthy
4.damage to critical infrastructure eg water bourne disasters, mental health stress, disrupt access to essential services, sewerage systems
5.population displacement=loss of national territory, inhabitable
6=economic reliance on fishing and tourism lost
121
what actions are being taken by the kiribati government to combat sea level rise threat
1.coastal protection and rehab= construction of protective structures , replenish eroded land, explore habitable land, increase natural resilience
2.long term development planning eg coastal
3.climate adaptation programs eg kap which reduces vulnerability and decrease coastal erosion
4.nature based solutions and community engagement eg australia kiribati climate security initative, implement resilient infrastructure
5.migration, promotes migration with dignity, short term migration, more attractive and encouraged, bought land from fiji-vanua levu, potential refuge currently used for food production
122
reasons for sea level rise risk in kiribati
-low lying land, none above 3m
-global sea level risen by 20cm since 1980 due to thermal expansion and polar ice caps melting
-uncertainity about how quickly and how much they will rise
123
what is hard engineering
involves construction or building, can be permanent or semi permanent
124
who are part of policy decision making
different players/stakeholders including residents, business owners, local tax payers, local council by overseen by defra
125
what is soft engineering
no construction or building required
126
what are the roles of stakeholders in policy decisions
residents-want hard engineering -durable, protects homes
local business owners-protection from damage
local taxpayers-cheapest alternatives but also protected
local council-cheap alternative however, protected as they are providing a service
environmentalists/ conservationalists-maintain biodiversity and habitats
127
4 types of coastal management
-hold the line= maintain current position of the coastline through hard engineering like gabieons, riprap, sea wall, groynes, beach replenishment, revetments
-advance the line=extend coast out to sea, eg through soft engineering like sand dune seeding, beach nourishment, groyne restoration, offshore breakwaters
-managed retreat/strategic realignment=allowing coast to retreat ef sea wall breaks, creates saltmarshes, breaches of floodbanks, can create shoreline management plan
-no active intervention eg allow nature to take its course, erosion, flood low lying land
128
4 factors affecting which type of coastal management is chosen
-engineering feasibility=achieveable?, within budget?
-environmental sustainability=protected sites eg sssi and nature reserves
-political , social or economic reasons= agriculture, tourism, individual properties at risk, are costs acceptable to current govt,
-impact on coastal processes=hold the line, disrupt sediment supply, beaches are narrower, kess lilely to become promoneries
129
bangkok background
-mega city
-chao phraya is the main river
-drainage density is high, rainfall is high so there are many rivers
-begins to form deltas, built on deltas, with distrubutaries and turbidity current =how able sediment is able to stay, build up over time and go out towards the sea
-flooding problem
130
issues with bangkok thailand
-very low lying, sea level rise problem
-storm surges are more frequent from tropical cyclones, cause significant coastal flooding, due to climate change therefore oceans are warming further, tropical cyclones all go west so thailand is constantly hit
-straightened the river to make navigation easier however the river flows faster, so sediment is deposited further out to sea, delta does not build up
-groundwater extraction causes subsidence, taken from under lying geology so land sinks, 1-2cm a year while sea level rises, eustatic and isostatic
-clay and soil and rock is slowly crumbling as the water is affected , skyscrapers weigh tons
-mangrove forests are being destroyed, for shellfish fishing, extensive shrimp farming, has to be done at the coast
131
4 solutions to bangkok flooding issue
-groundwater management=restricting water usage, personnel costs
-infrastructure projects=28, £4-6bn, improved drainage systems/centenary park, landscape parks, building as many given spaces as possible, redirect waterway smf underground tunnels, elevate flood walls and raised roads
-dredging and expanding roads=embankments, improving weather forecasts, 28 new flood prevention projects
-urban planning and relocating
132
what is tolus scree
material that accumulates at the base of a projecting mass of rock
133
what are rotational scars
fresh, curved, unweathered and unvegetated rock surface on the cliff face.
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