Extreme storms can help repair eroded coastlines

Extreme weather helps compensate for coastal erosion caused by rising sea levels by depositing large amounts of new sand along the receding coastline, according to new research.

According to researchers, a storm can remove large amounts of sediment from the deep sea and regenerate damaged beaches.

Large waves can wash sand off the beach and deposit sand along the surrounding coastline.

We now understand that extreme waves can contribute positively to the overall sand budget, despite the erosion of the upper beaches and dunes.Professor Gerd Masselink, University of Plymouth

This study was conducted by the University of New South Wales (UNSW) in Australia in collaboration with scholars from the University of Plymouth and the Autonomous University of Baja California.

In scenarios where future greenhouse gas emissions are at the top of the current model, climate change is projected to raise global sea level between 63 cm (25 inches) and 101 cm (40 inches) by 2100. I am.

Global warming is also expected to increase wave heights during extreme weather events along about three-fifths of the world’s coasts by the end of the century.

However, the findings could change long-term predictions about the future of our coast, researchers said.

Studies have found that the amount of naturally deposited sand on the coast matches the amount required by engineers for artificial “beach feed” projects used to control erosion.

In this survey, we surveyed the coasts of Australia, the United Kingdom and Mexico. Each experienced an episode of extreme storms, followed by mild weather and improved beaches.

In Australia, scientists focused on Sydney’s Narrabeen Beach after a storm strong enough to tear a pool from coastal real estate in 2016.

Coastal and seafloor measurements have theoretically shown that the increase in sediments due to severe weathering is sufficient to compensate for the predicted decades of coastline recession.

In the United Kingdom, researchers have collected monthly data and annual depth surveys from Perampos Beach on the North Cornish coast since 2006.

Perranporth was affected by extreme weather during the winters of 2013-2014 and 2015-2016, causing significant sand loss from the beaches and surrounding dunes.

However, by 2018, the beach had recovered 420,000 cubic meters (549,339 cubic meters) of sediment.

The dataset is limited, but researchers said it could reshape our predictions about the coast.

However, they warned that in coastal waters, it is difficult to say how much sand could sink along the coastline in the future, with some measurements of the seafloor.

Dr. Mitchell Harley of the UNSW Water Institute said: “During these events, hundreds of thousands of cubic meters of sand invaded these beach systems, similar to the scale engineers use to artificially feed beaches.

A new way to see extreme stormsDr. Mitchell Harley, University of New South Wales

“This may be sufficient to offset some of the effects of sea level rise caused by decades of climate change, such as coastline retreat. A new way to see extreme storms.

Professor Gerd Masselink, who heads the Coastal Process Research Group at the University of Plymouth, said:

“But we understand that extreme waves can contribute positively to the overall sand balance, despite the erosion of upstream coasts and dunes.

“We have already shown that coral reef islands can naturally adapt to withstand the effects of rising sea levels. This study means that changes in our own coastline are not completely negative for the effects of extreme storms. Indicates that you may do. “

– A single extreme storm sequence can balance decades of coastline withdrawal predicted from sea level rise. It is published in Nature Communications EarthAndEnvironment.

Source: Belfasttelegraph





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