What is coastal erosion and how will it impact Australia?


What is coastal erosion and how will it impact Australia?

The Australian governments could be given the power to force people in coastal areas to move from their land due to climate change, a report released in late October said.

FULL REPORT: Managing our Coastal Zone in a Changing Climate: the Time to Act is Now

A report into the effects of climate change on the coastal regions was issued by the House of Representative’s Standing Committee on Climate Change, Water, Environment and the Arts.

The 18 month inquiry said that rising sea levels, more frequent storms, cyclones and floods along the coastline are putting beach front properties at risk.

As a result the inquiry has canvassed the option of forced retreats with the “the possibility of a government instrument that prohibits continued occupation of the land”.

Queensland is noted as the most at risk as rising sea levels will potentially affect billions of dollars of beachfront housing.

The report does not go into whether landholders would be fully compensated for the forced retreats and, if so, who would pay.

Another option raised in the report is forcing coastal residents to pay a regular levy to compensate those amongst them who have to move due to climate change.

It concluded that action to combat the effects of climate change on the coast was urgently needed, as was national leadership.

It is estimated that 80 per cent Australians live near the coast.

What is coastal erosion?

Coastal erosion is the permanent loss of land along the shoreline.

The coast is constantly adjusting to changes in wave and tide processes and sediment supply, so it is important to distinguish between short-term changes in the coast and long-term coastal erosion.

Short-term shoreline change

Short-term shoreline changes do not constitute coastal erosion.

There changes occur over periods of days to several years. It is most obvious during storms when high wave energy actively removes sand from beaches.

During storms waves reach a backshore area and erode sand from it. The important function of this backshore is to act as sand reservoir during storms. In the following months normal weather and wave patterns may cause sand to be replaced on beaches.

Long-term coastal erosion

Long-term coastal erosion occurs over years to decades. The varying coastline is observed to gradually move landward.

This recession of the shoreline represents long-term erosion.

For the past two decades sea level rise has been singled out as a likely cause of erosion throughout the Pacific, the Australian Bureau of Metereology says.

But while rising sea level is one possible factor, climatic variability may also be a significant cause of coastal erosion.

Currently interannual changes in weather patterns can alter the wind, wave and sea level patterns on islands throughout the Pacific.

Natural causes of erosion 

*Changes in wave climate such as an increase in wave height, change in the angle of wave approach or increased frequency of high magnitude waves.

*Reduction in the amount of sediment delivered to the coast from reef.

*Rising sea level.

Human-induced causes of erosion

*Sand extraction from beaches that reduces the sand volume of the coast.

*Coral mining.

*Insertion of structures such as seawalls which locally alter wave processes and change sediment transport patterns.

*Removal of mangroves.

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