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A-Level CIE Geography Physical
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Natural Hazards
A-Level CIE Geography Physical
22 cards
Cards (62)
Great Barrier Reef
600
years old
Great Barrier Reef
2000km
long
2900
reefs
Great Barrier Reef
generates $
4bn
of tourism per year
Great Barrier Reef
1500
fish species
400
coral species
Great Barrier Reef
added to World Heritage list
1981
Huge mines extract mineral wealth across the Great Barrier Reef,
5
times more than expected
Reefs make up less than
1%
of oceans but support
25%
of species
Threats to the
Great Barrier Reef
Salinity
changes
Pollution
- nitrates (
77k
tonnes/year) from
increased agriculture fertilisers
Crown
of
thorn starfish
Rising sea temperatures
Damage
from
tourism
Opportunities and management of the
Great Barrier Reef
High
value tourism
2
million visitors per year
Whitsunday
Islands - snorkelling
Fraser
Island - 75 mile beach
Bioilluminescence
Turtles
Land-use
Zoning— General use areas &
preservation
areas
Great Barrier Reef
- Coal
Industry
Aus shipped $
30bn
of coal in 2014
Employs
50k
directly &
150k
indirectly
Mines
operate at a loss
Galilee basin
- Queensland - coal deposits - would emit 700mol tonnes of CO2 for 50yrs
Dredging
&
dumping
of coral reefs spoil
Destroy
Manatee
feeding ground
HOWEVER:
Mining increases jobs by
15k
& decreases
energy
prices
2015 - reef 2050 - $
80mil
for reef protection - no
climate change
plans
Christchurch bay - Sediment Cells
SEDIMENT SOURCES:
R.Avon
,
R.Stowe
Christchurch
harbour
, Christchurch
ledge
Keyhaven
& hurst beach (spit)
Rivers flow into sea at
Barton
&
Becton
IOW, shingles bank & hurst castle
SEDIMENT MOVEMENT PATTERN:
Moves through
suspension
- fine
sediment
Sediment
currents
Deposition on shingles bank as
waves
lose
energy
as they hit
long fetch =
fast
and high energy -
less
friction
Mangroves
CONDITIONS:
24
*C+
Rainfall exceeds
1.25l
Equatorial
coastlines
West =
8
species
East =
40
species
In lining of estuaries of rivers flowing into
shallow
seas
eg. Ganges & Brahmaputra
Low
Oxygen
&
nutrients
- high salinity & strong winds
FEATURES:
Shallow root
penetration
- buttress roots
Extensive
lateral spreading
Act as
filters
- removes
soil
& organic matter
Carbon
sink
in sediment - terrestrial & coastal
THREATS:
Over
-
exploitation
: fuels, dyes, poison, thatching
Challenging
environment for life
Rias
Form when
River Valleys
are
submerged
Eg.
Dartmouth
/Kingsbridge estuaries -
South Devon
Unusually
wide
R.Valleys - deep
sheltered waters
Poole Harbour - Brownsea
Island
used to be a
hill
V. Shallow - 45cm+
Dalmatian
Coastlines - rivers run parallel to the coast - leaves islands as they are
submerged
Eg.
Dalmatian
coast -
Croatia
Coastal Rebound
2024
Isotatic rebound =
coastal features
raised
Submergent coastlines
North sea
- off
Essex
coast
Submerge
low-lying
land masses
common in existing
r. valleys
Coral reefs overtime
1998 -
Bleaching
16
% of world coral was damaged - particularly
Puerto Rico
- SW= 100% beached up to 40cm
30
*C waters
2004 -
Glbal
assessment
1/5
world reefs damaged beyond repair
70
% of reefs threatened
persian Gulf -
65
% destroyed
% of recovering reefs has increased -
4%
to
33%
2010
-
Initaive
in climate change & coral reefs
19%
of world reefs lost - 35% threatened
2011
- Assessment of reefs
60
% under local threats - 75% when including global threats - 90% by
2050
Coral & people
500mil
ppl depend on reefs for some aspect of life
30mil
depend on them for their entire livelihood - mostly in
80
LICs
50%
of world population lives on coastline - increased pressures
2009
- world reefs = $
100bn
Major bleaching in 1998,
2002
&
2006
Seafood
1/
4
of fish catch in
LICs
Feeds
1m
in
Asia
15
tonnes of fish/km^
2
/ year
Sell surplus
Coral
triangle
Indonesia
New medicines
Chemicals
produced for reef protection
Bone grafts
Leukaemia
Other products
Economic
goods
Jewellery
etc
Live fish & corals
In
aquariums
Sand
&
limestone
In
construction
industry
Recreational value
Tourism
Snorkelling
etc
Coastal Protection
Buffers
adjacent shorelines through wave action & impact of
storms
Maintains productive mangrove
fisheries & wetlands around ports &
harbours
Florida
$
1.6bn
revenue
Global value = $
375bn
Framers Hill - Pahang - Malaysia
BACKGROUND:
Western Malaysia -
100km
from Kuala Lumpur
Rainfall =
20-140mm
/month
Temp =
118-22
*C
Humidity =
85-95
%
Altitude =
1456m
Vegetation =
Lower
montane Forest
VEGETATION OF SLOPES:
Brush
bundles
Bamboo
saplings
Coir rolls
Wooden
stakes
TEST RESULTS:
1 yr =
75
% of site 1 = covered by vegetation
90% of site 2 =
revegetated
control plot = 7 plant species present =
weeds
No more landslides - control plot =
undercutting
&
unstable soil
Frasers hill
-
Evaluation
of Success
Geostructures
- $
3k
to install - civil struuctures = $20k
Remote site
- increased transport &
labour costs
Geomaterials
- abundantly available
locally
Non -
polluting
- minimal maintenance &
supports biodiversity
Used to make coir rolls
7
straw wattles -
biodegrade
after 1 yr = fertilisers
18months later =
restored
cut slopes covered in vegetation & no more
landslides
Puerto Rico
mudslides
- Oct
1985
- 129 dead
70-805
step & hilly
4
largest cities on coastal plain province
USGS landslide hazards
project over
3.5yrs
Italian
Mudlsides
-
1951-98
1 year of rain over
2
weeks - May
1998
Area has
2
active volcanoes
Overdevelopment of slopes
Developers set fire to
vegetation
- loosens soil & increases
mudflows
Build on top of
lava
layers
The USA's
Eastern
Seaboard
Extensive
coastal
development
Tourism
- Atlantic city -
NJ
75
% Americans live
100kms
from sea
Flat
topography - NJ <
3km
above sea level
East coast
sinking
relative to sea levels
Barrier
beaches being destroyed by
storms
Methods of Management
1. Hold the
line
-
sea walls
vs destructive waves
2.
Strategic retreat
- Not possible in NYC,
Miami
or Boston
3.
New builds
are away from the
coastline
4. Atlantic city &
Miami Beach
- pump in dredged sand to
replenish
beaches
5.
Hard Engineering
-
sea walls
& groynes at sea right & Monmouth beach NJ
US Army = $64mil on
replenishment
- 30m washed off by
sea
Hard Engineering -
sea walls
& groynes at sea right & Monmouth beach NJ failed in
Texas
due to poor maintenance & Construction
Land-use management
1.
Massachusets
- can't build on coastal lands
2.
North Carolina
- land left for
erosion
- size of 30x annual erosion - now 60x
USA -
Eastern Seaboard
- events
Planning for 1 in
100yr
storm eg.
Chatham
- Massachusets (1987) smash barrier beach causing 20m of coastal erosion
Overcautious
Super Storm
Sandy
-
October 2012
Hurricane
force
winds
High tides,
Autumn
(highest) tide - full
moon
Storm Surge
New Zealand - Seasand mining at
Mangawhai-Pakari
2milm^3 mined of sand at
35-60m
over
35yrs
Pre
1970
- Mined from
Obama
beach - sand spit changed shape and badly eroded
1994
- 5 commercial extractors granted permits to dredge - up 10 165km^3 annually for 10 yrs only in water deeper than
25m
Groynes
built -
expensive
Working
party to oversee actions & establish a
sediment budget
Amount of sand is
static
- non-renewable
Aucklands shoreline variations can’t be proven to be due to
mining
Sand dunes
are sought after for
tourists
etc
Holderness Coastline
- UK
Boulder
clay - not much
energy
needed for erosion
longshore drift southwards
= no beach to
protect cliff
Ringborough
farm =
145
acres (1939) now =
70
acres
businesses suffer -
215
caravans lost -
9
left
East riding
- Hold the line
Withernsea
-
£7mil
gabions protection - £250k/year
Kilnsea - No defences -
can’t sell houses
-
flooding
Spurn point (spit) - 5km long - replenished by
longshore drift
- major in shipping into
Humber estuary
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