Transcript Crowded Coasts - SLC Geog A Level Blog

Topics to be covered:
 Competition For Coasts
 Coping With The Pressure
 Increasing Risk
 Coastal Management
 Fieldwork & Research – Zakynthos
AIMS
•To understand that physical factors create a
variety of different coastal environments
•To consider how humans use different coastal
environments and how they can also threaten
them
Key Question to consider:
 Why do coasts vary so much?
Mangrove Coastline
Tropical Coastline
Salt Marsh coasts
Polar Coastline
Desert Coastline
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A coast is ‘that part of the land most
affected by its proximity to the sea and
that part of the ocean most affected by its
proximity to the land’.
It is called the ‘Zone of Transition’.
The coastline is the frontier between the
sea and the land.
The coast is on either side of the coastline
in 2 zones....
Onshore zone – it extends up to 60km inland
COASTLINE
Offshore zone – reaches as far out as the Economic
Exclusion Zone (EEZ) which is 370.4km out to sea.
The coastal state has the rights all over the natural
resources of the water and the sea bed
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What is the difference between the coastline
and the coastal zone?
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The coast is an open system with inputs,
transfers and outputs
When all the inputs and outputs are equal it is
said to be in DYNAMIC EQUILIBRIUM
If one element changes then all the internal
equilibrium is disturbed
Human activity does this a lot on the coast
Global warming also increases storms and
rising sea levels increase coastal erosion and
flooding
Look at the set of photos in front of you….
a) Physical features shown?
Think about:
 Topography – shape of the coast
 Geology – rock type
 Relief – height or slope of the land
b)The human activities going on there and why
this location has been chosen.
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Exercise : Identify the features, opportunities,
value and pressures for each of the
following:
Reefs
Mangroves
Salt Marshes
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Low trees and shrubs with dense
roots that grow in the marginal
tidal zones between TROPICAL and
SUBTROPICAL seas and land.
Roots exposed at low tide and they
trap silt and create new land.
Adapted to area due to thick waxy
leaves which conserve water by
reducing transpiration during low
tide.
Salt tolerant ‘halophytes’ .
Protects against storm surges and
tsunamis.
Also provides fuel, timber for
building.
Cleared for shrimp aquaculture
and tourist resorts.
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http://mangroveactionproject.org/issues/man
grove-loss
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We have already lost over half of the world's original
mangrove forest area, estimated at 32 million hectares
(app. 80 million acres).
In 2007, less than 15 million hectares (37 million acres) of
mangroves remained.
About half of mangrove loss has occurred in the last 50
years, mostly in the last two decades, due to:
shrimp farming
tourism
urbanisation
agriculture expansion
roadways
Marinas and other intrusive developments.
The current rate of mangrove loss is approximately 1% per
annum (according to the Food and Agriculture Organization
- FAO), or roughly 150,000 hectares (370,050 acres) of
mangrove wetlands lost each year.
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Coral are living organism
called polyps, are tiny animals
that resemble a miniature sea
anemone, that secrete a
limestone (Calcium
Carbonate) base
3 types of reef: Fringe,
barrier reefs and atolls.
Charles Darwin first found
these three and realised
they were different stages
of a sequence
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Great Barrier Reef in Australia is the
world’s largest coral reef at 1500km long
and comprises of 2900 different reefs
Helps dissipate wave energy
Fragile and open to exploitation
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Conditions necessary for reef growth
Coral reefs are found largely between the tropics of Capricorn
and Cancer where:
water temperatures are warm. Corals are unable to thrive in
water that is much below 16 C and grow best with a range of
18-30 C. In the tropics there is little annual variation in sea
temperature. (But coral reefs are either restricted or absent
from along the west coast of the Americas, as well as the west
coast of Africa. This is due primarily to upwelling and strong
cold coastal currents that reduce water temperatures in these
areas.)
salinity is at favourable level. Freshwater kills coral and this is
clearly seen where rivers flow out into coastal reef areas.
Corals are restricted from off the coastline of South Asia from
Pakistan to Bangladesh. They are also restricted along the coast
around north-eastern South America and Bangladesh due to
the release of vast quantities of freshwater from the Amazon
and Ganges Rivers respectively.
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clear water prevails. Silt that discharges at a river mouth
will blanket the coral and affect the feeding mechanism of
the corals and animals on the reef. For example at the
mouth of the Amazon coral reef is absent due to the huge
quantities of silt that are released.
brightly lit waters that are fully penetrated by the sun’s
rays. So corals are restricted to depths rarely exceeding
37metres. Beyond this limit too little light is absorbed and
the algae that feed the corals cannot be supported
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See worksheet on the blog and text books
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Occur in estuaries where fresh water and sea waters
mix.
Defined as the vegetation that occurs on muddy shores
where boggy ground is either flooded by sea water
daily or less often.
Form on the shore due to a lack of wave action and the
tide.
Incoming tide moves across the sheltered shore
bringing sediment and detritus, the lack of wave
action results in this material settling out at slack
water.
Accretion takes place; sediment builds up forming soil
and can even raise the level of mud.
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Abiotic Factors: (Non Living)
Saline Mud/Soil: Seawater deposits salts (solutes)
in the sediment. Causing problems for plants
growing.
Waterlogged Soil: The air spaces within the soil
are filled with water rather than air. Roots need
oxygen for respiration as much as other parts of
the plant. Long-term waterlogging creates an
anaerobic condition of black mud, which is toxic
to plants.
Drag and Scour: The tidal movement across the
surface causes a sideways drag on the plant. With
two tides a day this will possibly uproot the
plants. The water contains sediment like sand and
mud particles and this will scour the plants like
being buffed with sandpaper.
Biotic (living)
 Salt tolerant plants grow - Halophytes. May even
be submerged for part of the day.
See Pearson p165
 Valuable ecosystems as reduce tidal energy and
provide a vital habitat to many wading birds.
Threats
 Reclamation eg for farming
 Industrial pollution
 Agricultural pollution causes eutrophication
 Shipping and bating causes wash which leads to
die back in vegetation
 Marinas and recreation adds pressure
 Global warming – high impact storms, changing
temperature and rainfall affects the plants and
sea level change.
Fill in the sheets about the
features,
value,
opportunities
and pressures
of these 3 high value ecosystems
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Sorting out succession…..on your Pearson
CD ROM