In comparison with many countries of the world, Australia possesses an enormous continuous coastline. Australia’s coast stretches for about 60,000km. Along the coastline there has to be some
consequences for the coastline to have some issues and affecting our coastlines.
The physical and human processes occuring?
In Collaroy/Narrabeen, Beaches regularly undergo cycles of erosion or growth in response to tides, wind and waves. This can make coastlines hazardous areas for development.
Collaroy/Narrabeen Beach is the beach most vulnerable to erosion from coastal storms on the Northern Beaches. It’s ranked Australia’s third most at risk area from coastal processes.
Waves: The power of waves is one of the most significant forces of coastal change. Waves are created by wind blowing over the surface of the sea. As the wind blows over the sea, friction is created – producing a swell in the water. The energy of the wind causes water particles to rotate inside the swell and this moves the wave forward. Waves can be destructive or constructive.
Deposition: When the sea loses energy, it drops the sand, rock particles and pebbles it has been carrying. This is called deposition. Deposition happens when the swash is stronger than the backwash and is associated with constructive waves.
In Vietnam, due to rich natural resources and other favorable natural conditions, coastal zone in Vietnam has become an area of active economic development and high population density. Recently, coastal environment and ecosystems in Vietnam have changed obviously due to combination of climate change and human activities. But recently there has been major issues with the coastal environment in Vietnam.
Pollution: As the number of active landfills diminish and coastal populations grow, offshore waste dumping and coastal pollution increase. This additional dumping increases the possibility of improper waste disposal polluting the coastal environment. Living coral reefs are particularly vulnerable to pollution, but other coastal environments suffer as well.
Waves: The breaking waves and resulting currents pick up and move sand, making beaches dynamic, perpetually in motion. This subtle but steadily flowing river of sand moves laterally up and down the shoreline, as well as offshore during storms and back toward land between storms.
Waves and currents affect this movement of sediment, but changes in sediment levels, in turn, affect the waves and currents.
Causes and consequences of environmental change
In Collaroy/Narrabeen, Urban development is at risk of damage from these coastal changes and by changing coastal stability, development itself can actually increase erosion risks. Buildings, roads and homes within the “active” beach system become vulnerable to extreme weather conditions, by sand drift, stormwater erosion and receding shorelines.
The Northern Beaches Council is trying to keep their people and properties impacted by erosion safe. This includes controlling new developments that could be damaged during storms, maintaining the protective vegetation on sand dunes, constructing and maintaining properly designed seawalls, as well as undertaking beach scraping and nourishment.
In 2016, erosion has damaged Cua Dai Beach. Sea water also overcame a 400m section of underwater sandbags to erode 10m of the beach, threatening coastal resorts and hotels. Recently, coastal environment and ecosystems in Vietnam have changed obviously due to combination of climate change and human activities. Climate change is global in scale and lead to sea level rise as a consequence of global warming, typhoon turbulence and ENSO phenomenon, and increase of coastal disasters.
Human activities in the basin such as upstream forest and mangroves deforestation, building sea and river dikes, construction of big dams, dredging channels, agriculture, aquaculture, over-catching, industry and domestics, have changed discharges of water, sediments, nutrients and wastes into coastal zone, and thus, have degraded marine and coastal environment.
In Collaroy/Narrabeen, Collaroy/Narrabeen Beach is the most vulnerable to erosion from coastal storms on the Northern Beaches. They are trying to protect the beaches from further erosion using these management strategies.
Dune management activities will include maintenance of dunes and their vegetative cover at Collaroy/Narrabeen. Existing areas of dune vegetation will be maintained and opportunities taken to increase the coverage of dune vegetation in other areas where possible. Natural sand dunes play a vital role in protecting our beaches, coastline and coastal developments from coastal hazards such as erosion, coastal flooding and storm damage. Sand dunes protect our shorelines from coastal erosion and provide shelter from the wind and sea spray. Sand dunes also provide a future supply of sand to maintain the beach. The wider the band of dunes, the larger the reservoir of sand. The height of natural dunes also provides protection from coastal flooding from storm surge and wave action.
Beach nourishment is an adaptation technology primarily used in response to shoreline erosion, although flood reduction benefits may also occur. It is a soft engineering approach to coastal protection which involves the artificial addition of sediment of suitable quality to a beach area that has a sediment deficit. Most importantly, beach nourishment reduces the detrimental impacts of coastal erosion by providing additional sediment which satisfies erosional forces. Shoreline erosion will continue to occur, but the widened and deepened beach will provide a buffer to protect coastal infrastructure and other assets from the effects of coastal erosion and storm damage.
In Vietnam in recent years as natural disasters seemingly caused by climate change take an increasing toll on tourism, one of the country’s major industries. Vietnam is no stranger to typhoons and flooding. But a changing climate is making things even worse. Rising sea levels could engulf beaches and other natural resources in coastal areas, damage cultural destinations, and flood tourism infrastructure. Which currently Vietnam is using some coastal management strategies to help with that.
Vietnam has made strong effort to protect coastal environment by establishing framework of organisations and legal base, developing capacity, building national strategies and plans, implementing coastal environmental projects, and strengthening international cooperation
A system of seawall has been established in order to protect plains and residences from sea and river
flooding. Across the country, there are up to 5,700 kilometers of riverbank and 2,100 kilometers of sea dikes. Sea walls are built in such a way that they tend to block the intensity of the wave crashing into the coastline or the shores so that there is no major damage caused to the human life-forms residing nearby. Also, another important feature of these sea walls is that they do not obstruct human activities that need to be done in such coastal areas.
Sandbags are being used to form temporary reefs, breakwaters, groynes, headlands or revetments on sand beaches. Sturdy geotextile bags are filled in-situ with local beach sand. Sandbag structures can be placed without the need for costly equipment or skilled labour. They can be used to form any form of shoreline structure. They are potentially most useful as a buried revetment under the dune face, where they will form a final line of protection after the overlaying sand has been eroded by storm waves.