Coastal erosion, heavy flooding forecast for Pacific

Coastal erosion, heavy flooding forecast for Pacific

Scientists are predicting storms from El Niño and La Niña events are likely to increase erosion and extreme flooding across coastal regions in the Pacific Ocean - including Australia's.

The multi-institutional study published by Nature Geoscience is the first to pull together data from across the Pacific to determine coastal patterns.


El Niño and La Niña phenomena refer to unusually warm and cold water temperatures, respectively, in the Pacific Ocean.


The study suggests La Niña-driven weather will lead to damaging coastal cyclones in Queensland and erosion on some New South Wales beaches.


Previous studies on coastal vulnerability have focused on sea-level rise.


But this latest research finds, irrespective of sea-level rise, storms from El Niño and La Niña events will lead to increased coastal erosion.


Co-author Andrew Short, from the School of Geosciences at the University of Sydney, says the effects on Australia's coastlines could be worse than previously anticipated.


"What this will mean down in our region is that, when we get increasing La Nina signals, we'll get more storms, more intense storms, in the Coral and Tasman Seas, which will lead to greater beach erosion along the southern Queensland, New South Wales, east Victorian and east Tasmanian coastlines."


Professor Short says better understanding of what drives the movement of waves around Australia's coast means authorities should be better able to predict beach erosion.


Communities would then have time to plan and prepare.


"If we know that these events are coming, we can make the changes in our coastal management and the way we manage our coast so we can, hopefully, avoid any catastrophic erosion, or catastrophic damage, in the future."


The study was conducted by 13 institutions, including the University of Sydney, and used data from across the Pacific Ocean basin from 1979 to 2012.


It gathered data from beaches in 48 countries, including Australia, the United States, Canada, Japan and New Zealand, along with, specifically, the U-S state of Hawaii.


In New South Wales, 15 coastal locations have been declared erosion hot spots, with buildings and roads at risk.


Byron Bay's Belongil Beach is among them.


Byron Shire Council mayor Simon Richardson says storm surges can take metres of the coast away.

"The threat is incredibly real. We have had houses go into the ocean along this strip back during some big storm events during the '70s and some that are very close to hazard lines now."


Since 1988, any people buying at Belongil have been informed they need to build properties which can be relocated, and they are told the coastline cannot be defended.


That council policy, known as "planned retreat," is now being contested.


A new management plan will either decide to keep the policy or to put rock walls in front of threatened areas.


Councillor Richardson says his council is just one of many facing big questions.


"These are the dilemas and these are challenges that all local councils up and down the East Coast, in particular, are facing. And we generally don't have the in-house expertise or the budget to really flesh out a good management response to it, and perhaps need state and federal government to really claim ownership of what is billions upon billions of dollars' worth of infrastructure."


The organisation Positive Change for Marine Life has been campaigning against building a rock wall.


Chief executive Karl Goodsell says 90 per cent of research suggests rock walls harm the environment and change the coastal dynamics.


He also argues ratepayers should not have to pay to safeguard the interests of a few landowners.


"What people need to start doing, and we need to start realising, is that we don't build close to a coastline. We can't stop the ocean. We can't stop nature. And that's been proven throughout this history of human beings, that nature is a far greater force than we are."


The researchers say the findings will help Pacific coastal communities prepare for the effects of changing storm patterns.


And they hope to do further research in South America and the Pacific Islands.


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