Sea Level Rise and Hard and Soft Engineering Flashcards

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1
Q

Define Eustatic sea level change?

Everyone

A

A Global change in sea level resulting in a fall or rise of the volume of water in our oceans.

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2
Q

What are the two main causes of eustatic change?

A

1.Changes In Climate- Temp decrease= more ppt falls as snow, increasing the volume of water stored in glaciers

Temp Increase= freshwater glacial melt, thermal expansion.

  1. Tectonic movements of the Earths crust= changes the shape of ocean basins
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3
Q

Define Isostatic sea level change?

A

A Local change in sea level resulting in the fall or rise of the land relative to sea level.

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4
Q

What are the three main causes of Isostatic change?

A
  1. ISOSTAIC READJUSTMENT-uplift/ depressions within the Earths surface due to the accumulation or melting of ice sheets.
  2. Subsidence of land due to draining of groundwater stores eg: marshland drainage
  3. Tectonic (crustal) processes as one plate is forced under another.
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5
Q

Describe past sea level fluctuations?

A

21,000 years ago= last GLACIAL maximum, sea levels were 130 metres lower than current situation
12,000 years ago- last glacial period, slowly started to melt
4,000 years ago- fluctuations began
1930- sea levels begin to rise

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6
Q

What does the IPCC predict about sea levels in 2100?

A

Sea levels will rise by 8-6 mm each year

Currently 2mm each year

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7
Q

Sea Level Rise CASE STUDY?

A
  • The Republic of Kiribati
  • 33 low lying Islands within the Pacific Ocean
  • Predicted many Islands will be lost within the next 50YEARS, rising by 1.2cm each year (4X GLOBAL AVERAGE.

President Tong- bought 20km of land on Fiji Islands- contaminated groundwater, cant grow crops.
“Migrate with Dignity”- help relocate in New Zealand as Kiribati’s population will become environmental refugees.

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8
Q

How are emergent landforms formed?

A

FALL in relative sea level, isostatic rebound takes place faster than eustatic sea level rise.

Raised Beaches- former wave cut platforms exposed due to rise in sea levels
Relict Cliffs, Stacks, Caves- become covered in vegetation and are gradually weathered over time

eg: NW of Scotland on Isle of Arran

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9
Q

How are submergent landforms formed?

A

RISE in relative sea level, isostatic rebound takes place slower than eustatic sea level rise.- floods land

Rias- flooded RIVER valleys, gentle, long, sloping cross sectional area.
Wide and deep at mouth-CROSS SECTION?
eg: Milford Haven in Pembrokeshire

Fjords- flooded GLACIAL valleys, straight, narrow, very steep sides. NOT deepest at the mouth= THRESHOLD

  • CROSS SECTIONAL AREA?
    eg: Sogne Fjord in Norway-200km long

Dalmatian Coasts- flooded valleys that run parallel to the coast (unlike fjords and rias that run parallel)
eg: The Coast of Croatia

SPATIAL AND TEMPEROL- take place globally at different locations and different speeds.

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10
Q

Define Coastal Management?

A

The protection of the coastline from increasing pressures and implications from natural processes and human activity.

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11
Q

What two things does coastal management look to protect homes and businesses from?

A
  1. EROSION

2. FLOODING

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12
Q

What are the four options when it comes to costal management?

A
  1. Hold the line- maintain defences
  2. Advance the line- build new coastal defences further out to sea.
  3. Manged Retreat/ Realignment- allow shoreline to move, but only to where it will do the least damage eg: flood farmland not houses.
  4. Do nothing- allow nature to take it’s course.
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13
Q

Define hard engineering?

A

The use of entirely artificial, built structures using long lasting materials eg: concrete, steel.

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14
Q

H- SEA WALL

A

A large concrete barrier that ABSORBS wave energy.
Some have recurved ends to deflect wave energy BUT this can cause strong, base eroding backwash.
+High value land protected
-expensive to build and maintain (£6000 per m), unsightly.

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15
Q

H- Groynes

A

Artificial fences built at right angles to the sea.
Trap sediment transported by LSD, widens beaches and allows increased absorbtion of wave energy.
“localised”
+relatively cheap to install and maintain
- deprive down- drift beaches of sand

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16
Q

H- Rip- rap

A

Boulders of granite and other hard rock that are placed at the base of a cliff and absorb wave energy.
+relatively cheap and look natural within coastal environment
-can move during storm events

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17
Q

H- Revetments

A

Sloping structures made out of wood/ concrete placed at the base of a cliff to absorb wave energy.
+expensive to built but relatively cheap to maintain , more natural looking than sea wall
-They create a strong back swash

18
Q

H- Offshore Breakwater

A

Concrete blocks/ boulders deposited off the coast, force waves to BREAK sooner offshore.
+produce “buffer effect”, decrease wave energy, don’t affect beach
- very expensive, can be damaged in storm events

19
Q

H- Gabions

A

Rock filled cages built at the base of a cliff. Absorb wave energy and reduce erosion.
+relatively cheap to install
- can be damaged in storms,

20
Q

H- Tidal Barriers and Barrages

A

Barrier- built across river estuaries, contain floodgates that can be used to protect against flooding

Barrage- dams built across river estuaries= MAIN PURPOSE IS TO GENERATE ELECTIRICTY- water is trapped behind dam at high tide, controlled release of water generates electricity.

VERY EXPENSIVE, may disrupt sediment flow.

21
Q

Define soft engineering?

Why soft engineering?

A

The use of natural systems and processes that are environmentally friendly to manage costal erosion and flooding.
Seen as more SUSTAINABLE by stakeholders, generally cost less than hard.

22
Q

S-Beach Replenishment?

A

Sand and shingle are added to beaches from elsewhere- DREDGING.
This increases the width of the beach and therefore decreases wave energy.
+increased buffering, absorbs wave energy, more natural
-dredging can disrupt tourism and marine life

23
Q

S- Beach Stabilisation?

A

Decreasing the angle/ slope of a beach and planting vegetation= wider beach= decreased wave energy.
+decreased erosion, absorbs wave energy
-cheap, natural, adds to and creates habitats.

24
Q

S- Managed Retreat?

A

Allowing the sea/ erosional processes to breach sea defences and allowing land to flood.
Over time, vegetation will COLONISE and marshland will form.
+new habitats, very cheap, marshland absorbs w.e
-conflicts can arise over which areas should be flooded, compensation.

25
Q

S- Cliff regrading and Drainage?

A

Decreasing the angle or overhang of a cliff and fitting drainage pipes within it to decrease saturation from infiltration and likelihood of land slumps/ slides.
+ cheap and prevents mass movement
- if becomes too dry can crumble and collapse

26
Q

S- Dune regeneration/ stabilisation

A

Planting marram grass and fencing off areas with board walks from tourism.
+ natural, creates habitats
- usually not followed/ respected by tourists

27
Q

Soft Engineering Case Study?

A

Wallasea Island in Essex- JOEY IS BUILT LIKE A WALL

  • The pre-existing wall was badly affected by erosion due to lack of maintenance and strong backwash.
  • This lead to managed retreat/ realignment, and then a new sea wall being built behind this- no opposition from Wallasea Farms (land owners).

COST 8 MILLION

28
Q

What is a SMP?

A

Shoreline Management Plan- management strategies that
Focus on sustainability eg: soft engineering is more sustainable than hard as it costs less and effects the environment less.
NATIONAL/LOCAL POLOCIES- 22SMP’s over 11 s.c
(All the local authorities in one sediment cell cooperate to form a SMP)

29
Q

What principle are sediment cells based on?

A

The sediment cell principle- intervention is largely self contained.

30
Q

What are the coastal management options within a SMP?

A
  1. Hold the line
  2. Advance the line
  3. Managed retreat
  4. Do nothing
31
Q

What is a ICZM plan?

A

Integrated Coastal Zone Management Plan- management strategy that considers all elements of the coastal system.
LAND, WATER, PEOPLE, ECONOMY

32
Q

How is the ICZM integrated?

A
  1. Environment viewed as a whole
  2. Different uses are considered eg: fishing, tourism, industry.
  3. It’s a DYNAMIC strategy , decisions are re-evaluated of demands change.
33
Q

What scale is the ICZM?

A

Local, Regional and National involved

34
Q

What processes are involved once a ICZM plan is established?

A

Managing and monitoring Implementation

Info Collection

Planning

Decision Making ( reoccurring cycle )

35
Q

Near ICZM Plan: Sefton Coast

A

Lies between the estuaries of the Mersey and Ribble in north-west England.
Takes into account wildlife: “SEFTON COAST LIFE PROJECT= more conservation”
Sefton Coast Partnership (SEP) is an informal association of land managers, land owners and the community council.
WHOLE SCALE plans.

36
Q

Far ICZM Plan: Odisha Coast

A

S-E coast of India, borders with the Bay of Bengal

Loss of energy as estuaries meet sea= hexadeltic region- 6 deltas. LOW LYING

37
Q

Opportunities in Odisha?

A

Flat land for settlements
Aqua farm industries such as shrimps
Tourism
Potential for wind and tidal energy due to offshore winds.

38
Q

Risks in Odisha?

A

Storm surges due to low lying land

Hot climate= cyclone facilitation eg: Cyclone Phalin in 2013, 44 dead and 700,000 billion in losses.

39
Q

Management and ICZM ?

A

Manage major issues such as coastal erosion
Tackle vulnerability to cyclones- 50 cyclone shelters
Protect mangroves and environment quality.

55 new shelters- Jajpur= 11
Odisha State Disaster Management Authority (OSDMA)

40
Q

Holderness Coast (Quiz yourself on sheet) ?

A

North coast- Borders the North Sea
Flamborough Head, Bridlington Bay and Spurn head Spit =61km

One of Europe’s fastest eroding coastlines at 2m/ annum.
By 2050 Holderness is predicted to see a sea level rise of 5cm

Human Intervention at Mappleton has have increased erosion further down the coast.
1.9 million plan at Mappleton in 1991 introduced groynes and rock barriers.

41
Q

How much did the human intervention at Mappleton on the Holderness Coast cost and when?

A

1.9 MILLION

1991- accelerated erosion rates elsewhere.