WORDS
Constructive waves
Corrasion
Corrosion
Deposition
Destructive waves
Erosion
Fetch
Foredune
Hydraulic action
Longshore drift
Refraction
Surf and swash zone
Vegetation
succession
Wave height
Wavelength
COASTAL MANAGEMENT
DEFINITIONS
small low-energy waves that deposit sand onto beaches
occurs when waves crash over rock shelves and move rock and other
material helping to erode the rock shelf away
the action of salt on minerals like iron that are contained in rock,
weakening the rock and making it more susceptible to erosion
the depositing of sand and rock particles caused by wind and wave
action forming features such as beaches
large waves formed by tropical cyclones and storms that erode material
from beaches
the removal of rock and sand particles as a result of wind and wave
action
the distance that wind travels over the ocean to form waves
the closest dune to the ocean or the first dune in a sand dune system
where waves enter cracks in rocks, air is compressed by the force of the
water causing erosion and forming features such as blow holes
the process, caused by waves hitting the coast at an angle, that is
responsible for moving sand along the coast
the bending of waves around headlands and into bays
the active part of the coast in terms of erosion and deposition of sand by
wave action; the surf zone is immediately adjacent to the coast and the
swash zone is at the shore once the waves have broken
the natural progression of vegetation from low-lying, salt-tolerant plants
on the foredune, through to shrubs and established trees on the hind
dunes
the vertical distance between the trough and the peak of a wave
the horizontal distance between wave peaks
GEOGRAPHICAL ISSUES IN THE COASTAL ENVIRONMENT
Australia is largely a nation of coastal dwellers with 85 per cent of the population living within
just 50 kilometres of the coastal zone. The pressure of urban development along the coastline has
caused a range of geographical issues involving various groups. Residents, tourists and
commercial-related activities all need to be managed by geographers so that the development of
the coastline is sustainable.
Pollution
Pollution from urban developments along the coastline is altering coastal ecosystems. Sewage outfalls
add nutrients to the water and pollute the water. Without careful management the water can become
unsuitable for swimming. In Sydney, urban stormwater is a major pollutant of the coastal
environment—between Palm Beach and Cronulla over 200 stormwater outlets discharge water
containing high levels of pollutants such as sediment, bacteria, heavy metals and organic chemicals
into the ocean.
Pollution from urban developments can pose a health risk to humans. Without careful treatment of
sewage and the management of stormwater, beaches can be unsuitable for swimming.
Tourism and recreational pressures
The coast is a popular destination for residents and tourists alike. Tourist developments and resorts are
concentrated in particular areas along the coast. During holiday times the population of these areas can
double, placing pressure on the infrastructure and environment of the area.
Recreational activities like four-wheel driving places pressure on the coastal environment. If not
carefully managed, large dune areas and beaches where vehicles are given access can be highly
susceptible to erosion.
Population growth
Overdevelopment and rapid growth of coastal areas occur due to the current Australian trend for
people to move from large cities to smaller coastal towns and villages where the lifestyle is more
relaxed. ‘Sea change’ is the name applied to this process. Some towns along the east coast of Australia
have imposed residential caps or a population ceiling for their town in an effort to stop
overdevelopment of the area.
Coastal rivers and lagoons
River entrances along the coast are prone to silting up as a result of both natural causes and human
actions. Careful management of these river entrances ensures safe and navigable access for boating and
provides tidal flushing of rivers and lagoons which keeps the environment healthy. This often involves
dredging and river entrance clearance of the many rivers and lagoons along the coast. The entrance to
the Murray River became so silted up it required four years of non-stop dredging to clear the river
channel entrance.
Dredging of the Murray mouth continues today and is likely to be a part of the long-term management
of the river entrance.
Introduced plants
Areas along the east coast have become invaded by introduced plants. The bitou bush or
Chrysanthemoides monilifera was introduced into Australia from South Africa in 1908 to stabilise
sand dunes and was used widely after sandmining activities in the 1950s. It can overtake native
vegetation and does not offer sand dunes the same protection against wind erosion as those covered by
native vegetation.
Influencing decision-making
Making decisions on the appropriate use and management of coastal areas involves detailed
knowledge of the natural processes that shape and form them. In addition a wide range of perspectives
or viewpoints about how the coast should best be used or developed need to be considered. On
occasions, residents and interested groups need to take action to influence decision-makers such as
councils, governments and developers. Geographers play an essential role in determining the
suitability of developments and ensuring the sustainable use of the coastline.
Inappropriate development
Much of the appeal of the coast comes from the views and lifestyle offered by the location. A balance
needs to be achieved between development and the natural beauty or visual amenity of the area.
Government planning now includes strict rules in an effort to ensure appropriate development.
However, there are still poorly planned developments that alter the natural environment. Sand mining
and the construction of breakwaters, for example, have interrupted the natural cycles that have shaped
the coast. Large complexes such as the Holdfast Shores accommodation development in Adelaide are
appreciated by residents and tourists but opposed by many local residents because of the loss of
amenity to the beach front.
Activities
Knowledge
1 Describe how the settlement pattern of Australia is related to issues in the coastal environment.
2 Why is the sustainable development of the coastline the aim of coastal management strategies?
3 What trend has been labelled ‘sea change’?
4 Describe one government response to ‘sea change’.
5 Select four of the geographical issues facing the coastal environment presented in this unit. For each
issue identify the human actions that cause the issue.
6 What role do geographers play in developing management solutions to issues in coastal
environments?
Application
7 Study the inappropriate development image. Select one of the viewpoints below and write a letter to
the local paper about the advantages and/or disadvantages of the development.
a a resident of one of the new developments shown in the picture
b a long-time local resident of the area who appreciates the coastal views.
WAVES – WATER ON THE MOVE
When we think of coasts we usually think about waves. Waves are one of the most identifiable
features and are one of the key natural forces that shape coastal environments. They are a way
in which energy is transferred from one place to another. For effective coastal management a
clear understanding of the way waves shape the shoreline is essential.
The formation of waves
Waves are formed by the action of the wind blowing across the ocean. First the wind forms ripples,
then these form wavelets and finally waves. The distance the wind travels over the ocean to form a
wave is called the fetch. The size and speed of the waves is influenced by the strength of the wind and
the length of the fetch.
Natural wind energy forms the waves. As the waves travel towards the coast they take the energy from
the wind with them. Watching a buoy in the open ocean, waves cause it to move in an up-and-down
motion only.
When the waves enter shallow water the energy in the waves starts to interact with the sea floor. The
wave speed decreases, the wavelength becomes shorter and the wave height increases. Eventually the
wave peak travels faster than the wave base and the waves break and release the energy they contain
(see 7.5).
A broken wave forms the surf and swash zone. This is the active part of the coast in terms of erosion
and deposition of sand. As waves travel across the open ocean they form what is called a swell. If
waves travel only a short distance before they hit land they form a wind swell. A wind swell is marked
by a short wavelength and high frequency of waves hitting the coast. A ground swell forms when
waves have travelled across a greater distance of ocean before hitting the coast. A ground swell has a
longer wavelength and the waves hit the coast less frequently.
PAGE 154-156 4 DIAGRAMS
Activities
Knowledge
1 Outline the three stages in the formation of a wave.
2 What is the fetch? Why is it an important factor in determining the size and speed of a wave?
3 How do waves in the open ocean differ from waves closer to the shore?
4 Draw an annotated diagram showing wavelength and wave height.
5 Draw an annotated diagram explaining how a wave breaks.
6 Explain the difference between the three different types of waves.
7 Explain the difference between a wind swell and a ground swell.
Skills
8 Interpret the synoptic charts that tracked Tropical Cyclone Wati in the Coral Sea from 24–28 March
2006.
Application
9 A tourist to Australia has asked you to advise them on the best areas for swimming at local beaches.
Write a letter that explains to them the three types of waves and how to identify them.
10 Imagine you are the lifesaver on duty at a busy Sydney beach during a large cyclone swell. Write an
account of the day’s events.
GEOGRAPHICAL PROCESS SHAPING THE COASTAL ENVIRONMENT
The three key geographical processes that shape the coastal environment are erosion,
transportation and deposition. Waves and wind act to erode headlands and shape beaches. These
same forces then transport sand and other material to be deposited in other coastal areas
forming landforms like beaches and sand dunes.
Erosion of headlands
As waves approach the coast they bend or refract due to headlands and the contours of the ocean floor.
In the open ocean, wave energy is distributed evenly along the entire wave. Wave refraction causes the
wave energy to be concentrated in particular areas and less intense in others, as shown in 7.7.
The main erosional features found on coasts are around headlands. They are shaped by three processes
that are all related to waves.
• Hydraulic action—Waves crash against a headland. Waves enter cracks in the rock and air is
compressed into the crack by the force of the water being pushed by the wave. As the air is
compressed it acts to erode rock. Blow holes are a common feature formed by hydraulic action.
• Corrasion—Waves crash over rock shelves. The wave action moves rock and other material across
the rock shelf and wears away the rock in an abrasive fashion.
• Corrosion—In rocks along the coast there are minerals like iron. When waves break they wet the
rocks. As the rock dries the salt in the sea water crystallises and acts on the minerals in the rock to
erode material.
PAGE 156-157 3 DIAGRAMS
Famous Australian ‘apostle’ lost to the waves
On the Great Ocean Road in Victoria are some of Australia’s most distinctive coastal landforms—the
Twelve Apostles. These are seastacks in Port Campbell National Park that are made of rock formed up
to 20 million years ago. They were created by the sea gradually eroding the soft limestone cliffs.
Waves erode coastal headlands but the rate depends on the type of rock. One of the famous
‘apostles’—a 45-metre stack—collapsed into the sea in July 2005.
The stack that collapsed in 2005 was not the first to disappear into the sea. In January 1990 the feature
called London Bridge, which was a natural arch that linked the mainland to offshore rocks, also
collapsed.
Deposition and transportation along the coast
Once material is eroded away by the wind and waves it is transported to other places to be deposited.
Depositional landforms include beaches and coastal dunes, which are shaped by the action of the wind,
waves and prevailing ocean currents.
PAGE 158 1 DIAGRAM
Beaches
Beaches are one of the most obvious depositional landforms of the coastal environment. Formed from
eroded rock and shell material they are accumulations of sand that occur along the shoreline. They are
a dynamic environment as they are constantly being reshaped.
During severe storms beaches can lose large quantities of sand through erosion by waves. Often the
eroded sand will be deposited offshore, forming a sand bar off the beach where it helps to limit the
impact of the erosive waves on the coast. The sand that is removed will be eventually returned
naturally by smaller constructive waves, restoring the beach to its former state in what is called the
erosion-accretion cycle.
Coastal dunes
Coastal dunes are formed by the action of the wind. Once sand is deposited on the beach it is then
subject to aeolian (wind) transportation.
The wind blows the sand landward, which is then trapped by low-lying vegetation like coastal
spinifex. The foredune is a store of sand. It may be eroded away, or it may continue to increase in size
depending on wave and wind action.
The foredune provides a buffer zone for the fragile dune vegetation located on the hind dunes. Easily
eroded, the plant communities can quickly recolonise and stabilise the area after periods of erosion,
allowing the dune to quickly form again. In this way dunes play a vital role in the protection of
property and developments from erosion.
PAGE 159 1 DIAGRAM
ACTIVITIES
Knowledge
1 Name the three key geographical processes that shape the coastal environment.
2 What is wave refraction and why does it occur?
3 Use a diagram to explain how wave refraction leads to the uneven distribution of wave energy along
the coastline.
4 Name the most common erosional landforms found along the coastline.
5 Describe the three wave action processes that shape headlands.
6 Explain the operation of the erosion–accretion cycle.
7 Name the three forces that shape depositional landforms on beaches.
8 Name the most common depositional landforms found along the coastline.
9 Explain the process that forms coastal dunes. What role does vegetation play in their formation?
10 With the aid of a diagram describe the process of longshore drift. What role does this process play
in transporting sand along the coast?
11 Select two erosional and two depositional landforms found on coasts. Sketch them into your notes
and describe the processes that have formed each landform.
12 What role does the foredune play in protecting coastal areas?
13 Read the snapshot about the loss of one of the Twelve Apostles and use your knowledge of the
coastal environment to answer the following:
a Where are the Twelve Apostles located?
b Why are they a popular tourist destination?
c Describe how the Twelve Apostles were formed.
d What was London Bridge? What happened to this landform in 1990?
e Do you think the collapse of the landforms along the coast could have been prevented? Explain your
answer.
Application
14 Imagine you are a park ranger employed at Port Campbell National Park. Prepare a brief talk that
explains the formation and eventual destruction of the Twelve Apostles.
15 The local council has decided to buy back residential property located on a headland and a
neighbouring foredune that is subject to severe erosion. Local residents who own the property say the
council is depriving them of their spectacular views, relaxed lifestyle and valuable property.
Write a newspaper article that evaluates the council’s decision to buy back the properties. The article
should present facts and consider a range of opinions about the issue. As a part of the article you will
need to present an opinion on the property buy-back proposal.
MANAGING THE COASTAL ENVIRONMENT
Coastal management involves developing strategies that are designed to protect and preserve the
coastal environment. Human actions have altered the operation of the natural coastal processes.
Intervention is often necessary in order to protect property, make areas safe for boating and
restore the environment.
Coastal management strategies
Management strategies involve careful consideration of the geographical processes that shape and
transform the environment. There are a number of coastal management strategies that have been
developed to manage coastal environments around Australia. Often a combination of some or all of the
following strategies will be used to manage coastal areas.
Construction of protective barriers and walls
Using rocks and concrete to create structures which stop erosion are a frequent management strategy
used along the coast. There are three basic types of constructed walls.
• Sea walls—Used to stop erosion of the coastline and protect property. Sea walls often replace the
foredune, which is an essential part of the beach erosion– accretion cycle and the scenic appeal of the
beach may be reduced by their construction.
• Breakwaters—Constructed at the entrances to rivers, they extend into the ocean in order to stabilise
river entrances and provide safe access for boating by keeping the river entrance clear of sand buildup. However, these breakwaters can act to dramatically alter patterns of erosion, transportation and
deposition of sand along the coastline.
• Groynes—Constructed along beaches (almost at right angles to the shore) to catch sand and make
beaches wider. As a management technique they rely on the sand carried by longshore drift. They
protrude into the ocean and are designed primarily to slow down the rate of longshore drift. However,
sand tends to accumulate on one side only, creating a different beach from its natural shape. Groynes
were traditionally made out of wood or rocks and concrete. Textile bags filled with sand are now being
used instead in many areas.
Beach nourishment
Beach nourishment involves the movement of sand by machines. Large quantities of sand are moved
from a point where it accumulates to a point where it has been eroded. As a beach management
technique it is expensive and needs to be ongoing. Dredging river mouths along the coast is a common
source of sand for beach nourishment.
Coastal dune preservation
Coastal dunes play a vital role in the coastal environment and there are a number of strategies used to
manage these areas.
• Limiting any new developments that occur in coastal dune areas. This allows the dunes to play their
natural role as a buffer between the beach and the land and avoids councils having to develop and
build elaborate sea walls to protect property.
• Constructing fences to control access of pedestrians and vehicles across sand dune areas. This helps
stop erosion as trampling vegetation removes the protective covering.
• Revegetation to help stabilise the dunes when the natural vegetation has been removed.
Group and community involvement in coastal management
The coast is a popular recreational environment that all Australians enjoy. It is essential that the area
be preserved for future generations. Coastal management schemes need to be not only based on a
sound understanding of the natural coastal processes that operate but also ensure access to the coastal
areas for the community. For this reason it is essential that coastal management schemes have the
support of all levels of government as well as community groups.
ACTIVITIES
Knowledge
1 In your own words describe what coastal management involves.
2 List the coastal management techniques discussed in this unit.
3 Prepare a table of coastal management strategies listing the advantages and disadvantages of each:
Brief description of management strategy
Advantages Disadvantages
4 Why do effective coastal management schemes often involve a combination of management
techniques in order to protect and preserve the coastal area?
Application
5 Outline the most appropriate coastal management strategy for the following issues along the
coastline:
Description of problem
Proposed management solution/s
Fishermen from a coastal village anchor their
boats in a small river. Recently the river mouth
has been eroded by the ocean and the river
entrance is no longer safe for ships to use.
A tourist development has been built behind
a well-preserved sand dune system. Tourists
wanting to access the beach are trampling and
destroying fragile dune vegetation.
Developments along the coast have changed
the shape of a safe swimming beach popular
with families. It is often dangerous to swim.
Hotel owners are demanding that the beach be
restored to how it was before the developments.
Storm waves frequently threaten to destroy
property along the foredune of a beach.
TO BE USED WHEN FOCUS TOPIC
TWO CASE STUDIES IN THE TEXTBOOK GEO FOCUS 2
1. GOLD COAST
2. TWEED HEADS (THE ENTRANCE)
3. FIELD WORK ACTIVITIES