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A Level Geography (OCR) > Coasts - Case Studies > Flashcards

Coasts - Case Studies Flashcards

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1
Q

How long is the coastline between Saltburn and Flamborough Head?

A
  • 60km
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2
Q

What type of coastal environment is Saltburn to Flamborough Head?

A
  • High-energy coastline
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3
Q

How does geology influence the coastline? (2)

A
  1. Discordant coastline = headlands & bays more varied than along a concordant coastline
  2. Differing rock types (different levels of resistance)
    a. Chalk (Flamborough Head & Selwick’s Bay) = resistant
    b. Kimmeridge clay (Filey Bay) = less resistant (0.8m/year)
    c. Shales (Robin Hood’s Bay) = less resistant (0.8m/year)
    d. Sandstone/limestone with interbedded glacial till (Saltburn) = resistant (0.1m/year)
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4
Q

How do waves influence the coastline? (5)

A
  1. Dominant waves from North & North-East
  2. Long fetch (1,500km) = long time to build up energy = powerful waves
  3. High tidal range (4m) = more potential erosion
  4. LSD (North to South)- sediment movement interrupted by headland = sand and shingle accumulate (i.e. Filey Bay)
  5. Wave refraction around headland (Flamborough Head) = formation of distinctive landforms
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5
Q

How does wind influence the coastline? (2)

A
  1. Prevailing wind from North/North-East drives high-energy waves
  2. Aeolian processes (but very limited)
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6
Q

Where has sediment within the coastline come from? (3)

A
  1. Nearshore area- driven onshore as sea levels rose at end of last glacial period
  2. Cliff erosion- i.e. from sandstone and chalk (resistant rock outcrops) & boulder clay deposits (gravel)
  3. River Esk BUT limited due to construction of weirs and reinforced banks along its course (human activity)
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7
Q

What landforms/cliff profiles are seen at Saltburn? (2)

A
  1. Limestone/sandstone with interbedded glacial till = resistant (0.1m/year)- stepped profile reflects more varied geology
  2. Horizontally-bedded strata = steepest cliffs along coastline
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8
Q

What landforms/cliff profiles are seen at Robin Hood’s Bay? (3)

A
  1. Shale = less resistant (0.8m/year)
  2. Wave-cut platforms (active erosion = cliff retreat)- 1* = shallow gradient with max width of 500m
  3. Possible shore platform created in last 6,000 years (constant level of erosion due to predom. stable sea levels)
  4. Headlands (sandstone) = more resistant bands either side of bay (0.1m/year)
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9
Q

What landforms/cliff profiles are seen at Filey Bay? (2)

A
  1. Kimmeridge clay (weak) = extremely susceptible to erosion (0.8m/year)
  2. Mass movement (slumping) = shallower angle cliff profiles
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10
Q

What landforms/cliff profiles are seen at Flamborough Head? (5)

A
  1. Chalk (resistant)- points of weakness = landforms
  2. Joints/faults exploited by erosive waves = caves & arches (i.e. Selwick’s Bay where master joint in chalk has been enlarged)
  3. Stacks (i.e. Green Stacks Pinnacle)
  4. Geos (over 50)- most aligned to the NE/NNE (facing dominant wave direction)
  5. Blowholes- where vertical master joints in the chalk have been enlarged
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11
Q

Why are there few developed beaches along the coastline?

A
  1. High-energy waves remove sediment before it can accumulate
  2. High tidal range (4m)
  3. Lack of estuarine environments that would provide sediment sinks
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12
Q

How long is the River Nile?

A
  • 6650km
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13
Q

What is the River Nile’s catchment area?

A

More than 3 million km(2)

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14
Q

How does the River Nile influence the formation of landforms? (2)

A
  1. Huge sediment load (sediment budget) = 30% clay, 40% silt & 30% fine sand
  2. Average annual sediment yield = 4.26 tonnes/ha/year (total = 91.3 million tonnes per year for the whole Blue Nile Basin in Ethiopia)
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15
Q

What are the 3 distinct sub-units of the coastal plain & their characteristics? (3)

A
  1. Foreshore plain- elongated ridges alternating with lagoons, salt marshes and alluvial deposits the depressions between them
  2. Frontal plain (south of foreshore plain)- scattered eroded limestone outcrops and clay deposits
  3. Sandy zone- variety of different sand formations (i.e. sheets, dunes, hummocks)
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16
Q

What are the two distributaries of the Nile Delta?

A
  1. Rosetta
  2. Damietta
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17
Q

How does wave action influence the delta?

A
  1. Wave action in the Mediterranean redistributes the sediment at the front of the delta
  2. The reworked sediment forms a series of curved barrier bars- close off segments of the Med Sea to form lagoons (turn into form of sub-environment & soon become filled with fine sediment)
  3. Low wave energy (low tidal range due to small entrance to Med - 2cm/year & small fetch) mean little erosion
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18
Q

What are the estimated surface current velocities at different times in the year? (4)

A
  1. 9.26-13.5 cm/s during summer
  2. 4.46 cm/s during autumn
  3. 23.14 cm/s during winter (strong winds
  4. 8.4 cm/s during calm spring weather
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19
Q

How does seabed topography influence the delta? (2)

A
  1. Shallow continental shelf = friction so waves lose energy (deposition greater than erosion)
  2. Provides surface for accretion
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20
Q

What is the prevailing wind & therefore wave direction? (2)

A
  1. NW winds = waves coming from west, NW, N (55-60% of time)
  2. Waves come from NE (8% of time)
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21
Q

Which physical factor is most important in influencing the delta?

A
  • Large scale factors (i.e. seabed topography, sediment budget) most important in influencing the delta over millennia, but on a smaller, more local, scale other physical factors (i.e. winds, waves) influence the movement of sediment over time along the coastline.
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22
Q

What are the landforms east & west of Abu Qir headland? (2)

A

. Beaches west contain long crescentic bar systems (associated with rip currents and negligible LSD)

  1. Parellel longshore bars exist along delta extending from east of Abu Qir to Port Said (created by dominant eastward longshore current & associated LSD of sediment)
  2. Manzala lagoon at Port Said (East)
23
Q

When was the Aswan High Dam built?

A
  • 1964
24
Q

How has the building of the dam influenced the delta? (3)

A
  1. Imbalance created between erosion and accretion
  2. Rapid reduction in amount of sediment accreted (120m tonnes/year to only trace amounts today)
  3. Changes along NW Nile Delta with accelerated erosion & rates of coastal retreat as high as 148m/year
25
Q

What has also contributed to higher erosion rates? (2)

A
  1. Rising sea levels in Med (1.2mm/year)
  2. Higher erosion rates as deeper water = large waves with higher amounts of energy (reach further inland)
26
Q

Where is Sandbanks?

A
  • Dorset
27
Q

Who is responsible for managing the Sandbanks peninsula? (3)

A
  1. Poole Harbour Commissioners
  2. Poole Borough Council
  3. Environment Agency
28
Q

What is the plan called to manage Sandbanks?

A

Two Bays Shoreline Management Plan (based on sediment cell covering Poole Bay and Christchurch Bay

29
Q

What options does the Environment Agency currently apply strategies from? (3)

A
  1. Hold the Line (HTL)- maintain, sustain or improve existing defences
  2. Managed Realignment (MR)- existing defences moved to more sustainable positions, usually further inland
  3. No Active Intervention (NAI)- areas of low economic value and/or high environmental value are not protected
30
Q

Why does Sandbanks need managing? (6)

A
  1. Large number of high value commercial properties (i.e. Sandbanks Hotel & Haven Hotel = both create employment/spending in local economy)
  2. Residential properties high in demand & command premium prices (4th most expensive in world per square metre)- e.g. large detached houses = + £10m // luxury apartments = + £2m
  3. Beach = major tourist attraction- e.g. Blue Flag award for water quality & gently sloping = safe safe for family swimming
  4. Provides protection/shelter from waves for Poole Harbour = popular place for water sports (i.e. wind-surfing, sailing, water skiing) & home to numerous yacht clubs & marinas (i.e. Salterns)
  5. End of peninsula = entrance to Poole Harbour (used by cross-channel ferries, catamarans & commercial ships)- LSD could cause harbour entrance to become clogged & shallow
  6. Climate change = sea level predicted to rise 0.6m here in next 100 years = flooding of properties // breach peninsula at lowest & narrowest point (2m above sea level & 50m wide at Shore Road and Banks Road) cutting off from mainland- est. £18m damage to residential properties in next 20 years if no management strategies applied
31
Q

What strategy has been implemented to maintain a deep and wide beach?

A

Rock groynes

32
Q

What do rock groynes do to maintain the depth & width of the beach?

A

Minimise movements of sediment along the beach at Sandbanks (by LSD) = prevents sediment from entering harbour entrance (keep access free to ships) & absorbs wave energy (reduces rates of erosion)

33
Q

What would rates of erosion be without rock groynes?

A

About 1m per year

34
Q

What other strategy is in use to conserve the beaches?

A
  • Beach recharge
35
Q

What is beach recharge?

A

Sand dredged from offshore is sprayed onto the beach (‘rainbowing’) adding to its size

36
Q

How much does beach recharge currently cost?

A

£20/m3

37
Q

What is a cheaper alternative to beach recharge? (3 + but…)

A

[2015 trial]

  1. Dumping sediment dredged from the harbour just offshore involves a much cheaper alternative (only £3/m3)
  2. Natural currents transport sand onshore where will help to build up beaches

BUT 2018 review = only 3% of the 30,000m3 sediment dumped off-shore had reached the beach after 18 months

  1. In total, + 3.5 million m3 sediment has been added to Poole Bay beaches
38
Q

How has the management of Sandbanks been successful?

A

Sediment budget surplus on the beach (beach profile widened = can absorb more energy)- NB: important due to climate change and resultant sea level rise.

39
Q

Unintentional impacts of management at Sandbanks (2)

A
  1. Dredging = deeper water in offshore zone = less friction = more energy (more erosion in future).
  2. Sediment deficit further along coastline (i.e. Burton Cliffs) = base of cliff unprotected = more susceptible to mass movement (slumping) = spatially limited success.
40
Q

Where is the Mangawhai-Pakiri coastline?

A

New Zealand

41
Q

What is sand used for? (4)

A
  1. Construction
  2. Concrete making
  3. Glass manufacturing
  4. Beach replenishment
42
Q

Why is the sand in the nearshore zone at Manghawai-Pakiri useful? (3)

A
  1. High quality
  2. Suitable for the construction industry
  3. Just 50km north of Auckland it is convenient for NZ’s largest and economically most dynamic metropolitan region
43
Q

What is the population of the Auckland region?

A

Over 1.5m (accounts for 2/3 NZ’s total pop & 35% of country’s GDP)

44
Q

How is the region growing rapidly?

A

Apart from business, finance and high-tech industry, tourism centred on Auckland’s outstanding coastal amenities is booming (2015 saw 2.3m foreign visitors)

45
Q

How long has sand dredging operated for & how much has been extracted?

A
  1. Operated for over 70 years
  2. 1994-2004, 165,000m3/year was extracted
46
Q

What are current rates of extraction?

A

Ended (2005) at Mangawhai but has continued at Pakiri Beach

Current rates of extraction = 75,000m3/year until 2020

47
Q

What is the sand extracted used for? (2)

A
  1. Replenishing Auckland’s tourist beaches
  2. Construction industry (many holiday homes & hotels being built in area)
48
Q

How has sand been deposited on the coastline? (3)

A
  1. During Holocene (past 9,000 years) = non-renewable
  2. Few sizeable rivers in area
  3. Most thought to have been derived from offshore
49
Q

What type of system is the coastline essentially & why significant?

A
  1. Essentially a closed system
  2. Outputs of sand not replaced by inputs from rivers, and waves from offshore
  3. Extraction rates at Pakiri Beach exceed input rates by a factor of 5
  4. Effect = deplete total sand supply stored in dunes, beaches & on sea bed (up to 2km offshore) = movements of sand between major stores have diminished
50
Q

How is the depletion of sand impacting on coastal landforms? (4)

A
  1. Beaches (starved of sediment) = wider and flatter = less effective in absorbing waves
  2. Higher energy waves erode beaches and landforms (i.e. dunes and spits) become vulnerable
  3. Foredune ridges undercut by wave action, developing steep, seaward-facing scarps
  4. Loss of vegetation cover = susceptible to wind erosion
51
Q

What happened in the 1978 storms? (2 + although…)

A
  1. 28-metre breach at the base of the Mangawhai spit- this (and second breach) altered tidal currents = sedimentation of Mangawhai’s harbour
  2. Shallower water in the harbour threatened Mangawhai’s waterfront community with flooding

ALTHOUGH subsequent dredging of the harbour and groyne construction on the spit has helped restore some equilibrium

52
Q

What complicates the fact that coastal retreat is attributed partly to sand extraction?

A

Climate change & rising sea level

53
Q

What is long-term retreat by the end of the century estimated at? (2)

A
  1. 35m
  2. Width of coastal zone susceptible to erosion varies (48-111m) but this estimate is higher than any of Auckland region’s other 123 beaches

A Level Geography (OCR) (11 decks)

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