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Geo physical > EQ3 > Flashcards

EQ3 Flashcards

1
Q

what are the two reasons why sea levels are rising?

A
  • ice caps and glaciers are melting (due to global warming)

- thermal expansion (as the sea heats up it expands and takes up more space)

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2
Q

what is eustatic change

A

when the sea level itself rises and falls. The change is global. In cold glacial periods precipitation falls as snow and forms ice sheets which store the water. At the end of a glacial periods as climate warms, the ice melts and sea levels rise.

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3
Q

whats isostatic change

A

when the land rises or falls relative to the sea. The change is local. In cold glacial periods the enormous weight of the ice sheets makes the land sink (isostatic subsidence). At the end of the glacial period as the climate warms, the ice melts and the land rises as the weight of the ice sheets reduce (isostatic recovery/ rebound)

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4
Q

what category does thermal expansion come under

A

eustatic

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5
Q

what category does ice caps and glaciers melting come under

A

eustatic

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6
Q

what category does terrestrial water storage, extraction of groundwater, building of reservoirs, changes in runoff, and seepage into aquifers come under

A

eustatic

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7
Q

what category does subsidence in river delta region, land movements and tectonic displacements come under

A

isostatic

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8
Q

what category does surface and deep ocean circulation changes, storm surges come under

A

eustatic

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9
Q

Kiribati case study- what is next and why are sea levels rising

A
  • only 1 meter above sea level
  • made up of 33 islands
  • sea levels are rising due to global warming
  • rising sea levels are contaminating groundwater
  • people will have to move to Fiji
  • population will become environmental refugees
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10
Q

what are submergent coastlines a result of?

A

sea level rise or isostatic sinking

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11
Q

what are the 4 submergent coastlines?

A

a ria, a fjord, a fjard, dalmation coats

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12
Q

submergent coastline: whats a ria

A

Narrow wonding inlet which is deepest at the mouth
- - associated with a rise in sea level
- occur when a valley is flooded
- they are sheltered winding inlets with irregular shorelines
- common in south west England

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13
Q

submergent coastline: whats a fjord

A

Flooded glaciated u shaped valley with very deep water and steep sides
- - formed when deep glacial troughs are flooded by a rise in sea level.
- the shallower entrance marks where the glacier left the valley
- can be seen in Norway

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14
Q

submergent coastline: whats a fjard

A

a flooded inlet with low rocky banks on either side

  • formed by post glacial drowning of glaciated low and rocky terrain .
  • can be seen in the gulf of finland
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15
Q

submergent coastline: whats a dalmatian coast

A
  • rivers flow parallel to the coast

- can be seen in croatia

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16
Q

what are emergent coastlines caused by

A

a result of isostatic rebound
rise in land

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17
Q

whats an emergent coastline (example)

A

raised beaches/ fossil cliffs/relic cliffs

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18
Q

emergent coastline: how does a raised beach/ fossil cliffs/relic cliffs occur, what is it

A

as the land rose as a result of isostatic recovery, former shoreline platforms and their beaches were raised above the present sea level.
often the remains of relic cliffs (eroded cliff lines) can be found behind the raised beach, with wave cut notches and caves as evidence of past erosion.
- can be seen on the west coast of scotland

19
Q

why does past tectonic activity have a direct impact on some coasts across the world, as well as sea levels?

A

due to the fact that they cause:
they may have a direct effect on the shape of a coast and coastla processes

  • uplift of mountain ranges at costal land at destructive and collision plate margins
  • local tilting of land, for example, some ancient Mediterranean ports have been submerged and others have been stranded above the current sea level

risk o tsunamis

20
Q

what are physical factors contributing to costal recession

A
  • weathering
  • mass movement
  • geology
  • marine processes
  • large destructive waves (up)
  • small constructive waves (down)
  • resistant rock
  • constant weathering
  • large scale mass movement
  • weakly consolidated rock
21
Q

what are human factors contributing to costal recession

A
  • offshore dredging
  • costal development
  • costal defences/ costal management
22
Q
  • make case study Holderness mind map
A

located in east yorkshire
-consists of lsd, geogoly, fetch and subariel
geology=unconsilated material-easily eroded- 2m a year
fetch- fetch isnt large norht sea- north sea is relatively depp doesnt experience and friction- hits land at a greater force- more erosion occures.
subariel processes
lsd-casues tgs- groynes paced at hornsea- starved mappleton- causing unequal distribution of sedimemt along the coast

social by 2100 200 homes will be lost
loss of recertional space and amenity value
econ
local tourism loses money, 1.2mil spent on repairs

env
loss of coatsl habists
up to 4m los in some spaces

23
Q

what is dredging

A

the removal of material from the seabed- used to make ports, beach nourishment

24
Q

what are the negatives of dredging

A
  • difficult for kids to do activities (e.g snorkelling)
  • removing seafloor species and damaging coral
  • increased swell as result of deepening the bay- resulting in erosion and need for costal defences
  • sediments converting marine communities
25
Q

what are the positives of dredging

A
  • port capacity increased- improved trade and navigation
  • may offset isostatic sinking
  • extra sediment and deposition may offset sea level rise (naturally or beach nourishment)
26
Q

case study- the nile delta and sea level rise and human activity.

A
  • the delta is experiencing retreat, significant erosion on half of it.
  • there is salt intrusion due to sea level rise
  • 2 million hectares of fertile land could be lost
  • at least 6 million people displaced
  • there is an integrated costal zone management ICZM
27
Q

what are the main 5 factors affecting costal recession:

A

wind direction, weather systems, seasons ,tides, storm activities

28
Q

costal recession: wind direction

A
  • the dominant wind produces the largest wave, most erosion occurs here, less erosion when winds are from other directions
  • links to fetch and how much the wavy can build up
  • a longer fetch means a more powerful wave
29
Q

costal recession: tides

A
  • there are two high tides and two low tides a day.
  • high tides=spring tides (when sun and moon are aligned so gravitational pull=strongest)
  • low tides= neap tides(when sun and moon are at right angles to each other)
  • tides determine where the waves will reach the shore
  • erosion at max when high tide is with destructive wave
30
Q

costal recession: weather systems

A

high pressure- air sinking- leads to dry conditions- brings about calmer conditions and smaller waves

low pressure- rising air- leads to wet weather- strong winds rotating in anticlockwise direction- larger waves

wind wants to go from high to low pressure zones- global warming has added more heat thus intensifying low pressure systems

31
Q

costal recession: storm activity

A

linked to a low pressure weather system, notably tropical cyclones and depressions. when air pressure is low over the sea, water is able to rise upwards, forming a dome of sea water under the depression. the lower the air pressure the higher the dome will be . the dome of water can then surge when the low pressure system moves near a coast. as tropical cyclones/ depressions are associated with strong winds, they create large storm waves the will appear on top of the dome. this adds height to sea levels and increases the risk of costal flooding, can join with high tide {all storms are low pressure systems}

32
Q

costal recession: seasons

A

winter waves= more destructive than summer waves.
winter waves- depressions are greatest - greater variety in difference in high and low pressure areas- greater wind speeds- low air pressure and faster winds- winter= season for hurricanes and storms (low pressure)- more erosion

33
Q

how do mangroves reduce threat of costal flood risk

A
  • reduce height of waves by 40%

- stabilises and traps sediment by keeping the land higher

34
Q

explain 3 physical reasons why some locations are at risk of flooding

A
  1. height above sea level
  2. amount of rivers flowing through that area (shape of landscape)
  3. tropical locations are more likely to receive tropical storms (low pressure)
  4. vegation
  5. subsidenecr
35
Q

what is the amenity value

A

its the value in cultural , human wellbeing and economic terms of an attractive environment that people enjoy using

36
Q

how does the level of development impact the consequences of costal flooding: Australia a developed country (soc, econ, env)

A 
ECON:
-tourism affected
-$67 billion road and rail at risk
SOC:
-hospitals and health services at risk
-close to 250,000 homes at risk
ENV:
-mangrove forests at risk
-great barrier reef at risk
37
Q

how does the level of development impact the consequences of costal flooding: Philippines: developing/emerging country (soc, econ, env)

A 
ECON:
-losses of $6.5 bil a year
-costal defences= expensive
SOC:
-around 2.3 mil affected
-high level of unemployment
ENV:
-corals and sea grass have been damaged by pollution
38
Q

5 soft engineering techniques

A
  • beach nourishment
  • cliff drainage
  • cliff regrading
  • managed retreat
  • dune stabilisation
39
Q

6 hard engineering techniques

A
  • groynes
  • sea walls
  • rip rap
  • revetments
  • offshore breakwaters
  • gabions
40
Q

what does sustainable costal management mean

A

it means managing current and predicted future risks to the wider costal zone in terms of peoples economic livelihood, social wellbeing and local culture and environmental impacts

41
Q

what are stakeholders

A

an individual or group of people who have an interest in the outcome of decisions made to change areas.

42
Q

what are winners

A

people who gain from a decision , either economically, environmentally or socially

43
Q

what are losers

A

people who are likely to lose property, their job, be forced to move, or see the coastline concreted over and view this as an environmental negative

44
Q

what are the 4 choices that can be made by the ICZM (integrated costal zone management)

A
  • advance the line
  • hold the line
  • managed retreat
  • no active intervention

Geo physical (9 decks)

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