GILES ACADEMY GEOGRAPHY
GCSE REVISION
UNIT 1—PHYSICAL UNIT
THE COASTAL ZONE
This unit explores how the coast is shaped by many processes including
weathering (through mechanical, chemical. Mass movement), Erosion
(hydraulic power, abrasion, attrition and solution), Transportation
(longshore drift, traction, saltation, suspension and solution) and
Deposition. It analyses the different landforms created as a result of
erosion (headlands and bays, cliffs and wave cut platforms, caves,
arches and stacks) compared to those created by deposition (beaches,
spits and bars).
You must understand the importance of sea level rise, the reasons and
consequences economically, socially, environmentally and politically
and be able to illustrate the impact of coastal flooding for a case study
example. In addition to the problems caused by coastal erosion
(Mappleton).
This leads to the major issue of how the coast should be managed.
Management strategies:
Hard engineering – sea walls, groynes, rock armour.
Soft engineering – beach nourishment, dune regeneration and marsh creation.
Managed retreat.
A case study of coastal management to assess the costs and benefits of
strategies adopted
In turn the need for conservation and the conflicts this has with other land
uses is fast becoming an issue. You are expected to know a case study
of a coastal habitat – its environmental characteristics; the resulting
habitat and species that inhabit it and reasons why.Strategies to ensure
the environment is conserved, but also allow sustainable use of the
area.
Coastal Zones and
Processes.
The coast is
shaped by
Constructive and
destructive
waves.
Destructive waves
Destructive waves have three main features:
1.
They are high in proportion to their length.
2.
The backwash is much stronger than the swash so that rocks,
pebbles and sand are carried back out to sea.
3.
They are frequent waves, breaking at an average rate of
between eleven and fifteen per minute.
Such conditions can occur anytime during the year, but are associated
with storms from the south west.
Destructive
Constructive
Constructive waves
The load of the waves - sand, shingle and pebbles - is deposited by
constructive waves. Such waves add more material than they remove
from the coastline.
Constructive waves have three main features:
1.
2.
3.
4.
They are long in relation to their height.
They break gently on the beach so that the swash carrying
materials up the
beach is stronger than the backwash carrying them away.
They break gently, with between only six and nine waves per
minute.
What Coastal Feature would be creating using;
a)
Destructive Waves?
b)
Constructive waves?
Coastal Zones and
Processes.
The coast is
shaped by
weathering and
mass movement
Weathering processes – mechanical, chemical.
Mechanical weathering is the breakdown of rock into smaller
particles due to such factors as freezing and thawing, release of
pressure, expansion and contraction from the sun or fire, plant root
growth, actions of animals, abrasion.
Chemical weathering is mostly from reactions with water or the acids
contained in rainwater.
Mass movement – sliding and slumping.
1. Name an example
location where mass
movement occurs.
2. Name an example of
a rockfall location.
Coastal Zones and
Processes.
The coast is
shaped by
Erosion and
weathering
Describe the processes of Abrasion,
Attrition, Solution and Hydraulic Action
in more detail.
Coastal Zones and
Processes.
The coast is
shaped by
Erosion
Headland and Bays will form where
steep cliffs are found on the coast.
The headlands are made of more
resistant rock and do not wear away
as quickly as the bays (softer rocks)
Explain the different processes that occur to form
Headland and Bays and a Wave Cut Platform
Coastal Zones and
Processes.
The coast is
shaped by
Erosion
If the coastline has well developed headlands and bays, the
headlands often show a variety of erosional landforms. Joints in
the headlands are eroded back to form caves which over time
are further eroded to form arches. The gaps in the headlands
eventually collapse and leave tall stacks at the ends of the
headlands. The stacks continue to be eroded by the waves until
only stumps are left and these eventually disappear altogether
Explain how the different
processes of erosion (Name
them!) are influencing the
headlands in each stage of the
diagram above.
Old Harry, Dorset
Coastal Zones and
Processes.
Long shore Drift
Deposition
A spit occurs were the process
of long shore drift happens at
a bend in the coastline. As the
coast changes direction the
long shore drift deposits
material on the bend. Over
time this builds up to form a
spit. Behind the spit a
saltmarsh develops as the
water becomes sheltered from
the waves and mixes with the
fresh water from the estuary.
The spit may develop hooks or
curves, this is due to the
second dominant fetch and
wind direction.
Case study
examples:
Hurst Castle
Spurn point
The coast is
shaped by the
processes of
transportation
If the wind blows so that waves come in
at a
sharp angle to the coast, the swash
carries
The pebbles at an angle up the beach.
When
The backwash moves by gravity back
down
The Beach, the pebbles end up at a
different
position. This process is repeated and
Pebbles gradually shift along the beach,
a
Process called longshore drift.
Tombolo and bars are formed in the same way
Complete the table below of all the coastal
features and their characteristics
Feature
Headland
and Bays
Wave cut
platform
Caves,
Arches,
Stacks and
Stumps
Spit
Bar
Longshore
Drift
Description of formation
Labelled Diagram
Example location
Consequences of
Rising Sea Levels
Reasons for
rising sea level
Why should we be worried if London floods?
THE COASTAL ZONE
COASTAL FLOODING CASE STUDY
LINCOLNSHIRE
As one of the flattest and most low lying areas of the UK, the Lincolnshire coast is very
much at risk from coastal flooding. High tides and storm waves are both risks but she is
the risk of potential sea level rise. With so much risks facing the area, defences such as
shown in the image above (beach nourishment – adding sand to the beach to make it
higher!) are very common along more populated area of the Lincolnshire coast
Impacts?
With most seaside resorts such as Skegness and Mablethorpe below sea level, the risk
of coastal flooding could severely damage tourism trade.
Buildings and infrastructure will be lost and will cut off some rural parts of the county
along the coast.
This in turn will effect employment which is already seasonal!
Rises in insurance costs and decrease in house and property prices could be very costly
for some.
For a location such as Donna Nook that is a key breeding ground for seal, coastal
flooding and sea level rise could damage such patterns and have effects on food chains
in other parts of the world.
In order to try and manage this, huge costs will be needed to defend and prepare the
area. In 2010, a £30 million project started to pump and reclaim sand from the sea to try
and rebuild beaches. These costs can and may increase dramatically!
Coastal erosion can
lead to cliff collapse.
This causes
problems for
people and the
environment.
Coastal erosion can
lead to cliff collapse.
This causes
problems for
people and the
environment.
• Why are the views above so
different?
Coastal
Management
Hard Vs
Soft.
Hard engineering
Sea Walls:
Often built in front of seaside resorts.
Very expensive. They aim to completely block the
waves and their effects. Life span of approximately
75 years. Can cause the erosion of the beach in
front of them. Socially reassuring for local residents.
Wooden Groynes:
Wooden "fences" built at right angles to the
coastline. They aim to stop the movement of
material along the beach due to long shore drift.
Their primary intention is to build up the amount of
sand on the beach. They have a life span of
approximately 25 years.
Gabion Groynes:
Large steel mesh cages filled with large rocks.
Aligned at right angles to the coastline. They aim to
do a similar job to wooden groynes. Expected life
span of 20 - 25 years, as the steel will rust.
Rip Rap / Rock Armour:
Large boulders, of 10 tonnes or more, are used as a
sea wall.
The gaps between the rocks allow water through,
which means that the energy of the waves is
dissipated very effectively.
It is important that the boulders are big enough to
withstand being eroded themselves and therefore
becoming part of the coastal system
Coastal
Management
Hard Vs Soft.
Soft Engineering
Beach Replenishment
Sand is either brought in from elsewhere, or transported back along a beach, usually
once a year. This is done using trucks, and is therefore very costly and time
consuming. Over the next 12 months the material is washed along the coast by long
shore drift, before being replaced again. The final method of coastal management is
of course to do nothing and allow the sea attack the coastline naturally.
Sand dune stabilisation
This is when sand dunes, that would naturally shift along the shore as a result of wind or wave
power, are artificially held in place. Stabilising dunes, using sand fencing or vegetation,
increases their effectiveness as a sea defence. It also stops the dunes 'migrating' into
developed backshore areas.
Salt marshes and mudflats
Salt marshes and mudflats are 'inter-tidal', being partly or completely submerged at high tide,
but exposed at low tide. They help absorb wave energy, which reduces their impact on
cliffs or defences behind them. It also reduces the cost of maintaining them.
Disadvantages of Coastal Management
Cost
Most of the solutions detailed are very costly, and in many places questions are being asked as to
whether they are actually worth the money.
Problems of disrupting the natural coastal system:
Whenever you tamper with nature there are going to be knock on effects, which could, in
time, become worse than the original problem.
Coastal defence strategies are often very localised, and can cause problems further down
the coast. One such example could be seen where groynes are used to trap
sediment. Further down the coast there could be a reduction in the amount of
material available to protect the coast there. This in turn would mean an increased
amount of coastal erosion.
1. Using a named example, discuss the advantages and
disadvantaged of coastal management.
2. Justify the reasons behind the differing strategies used in
Mineshead and Wallasea Island. (you will need your exercise book)
Coastal areas provide a unique
environment and habitat.
There is a need for conservation and this leads to conflict with
other land uses.
The Wash NNR (National Nature Reserve)
The reserve is a mix of open deep water, permanent shallow
water, mudflat and saltmarsh. The intertidal mudflats and
saltmarshes represent one of Britain's most important
winter feeding areas for waders and wildfowl.
Where: Lincolnshire and Norfolk
Main habitat: coastal
Star species: huge flocks of waders during the autumn; one
of the largest breeding colonies of common seal in the UK.
The Wash National Nature Reserve is the biggest reserve in
England, covering over 8880 ha. It’s also the most
important wetland site in the UK, with its vast mudflats and
huge expanse of saltmarsh supporting thousands of birds
all year round. In winter, the reserve attracts large
numbers of wildfowl including pink-footed geese, brent
geese and shelduck, while in the summer, waders and
seabirds come here to breed. The Wash is also one of the
best breeding areas in England for common seals .
How is this area used
sustainably?