The Times Australia
The Times World News

.
The Times Real Estate

.

How extreme storms can replenish beaches, not just erode them

  • Written by Mitchell Harley, Scientia Senior Lecturer, UNSW Sydney

Environmental scientists see flora, fauna and phenomena the rest of us rarely do. In this series, we’ve invited them to share their unique photos from the field[1].

Extreme storms can cause devastating erosion and leave beachfront houses teetering on cliff edges[2]. But our new research[3], published today, finds storms might also help replenish beaches by bringing in new sand from deeper waters.

We studied three extreme storms in Australia, the United Kingdom and Mexico. One, in Sydney in 2016, famously ripped a swimming pool[4] away from a property overlooking the coastline.

For the first time, we’re able to show just how much new sand can be added to a beach in a single storm alone – over 400,000 cubic metres in some cases. That’s equivalent to the typical volumes of sand[5] engineers use to nourish beaches artificially.

As sea levels rise, this natural form of beach replenishment might be an important factor in offsetting some of the damaging effects of climate change on beaches. Yet, with little knowledge of exactly how much sand is moving around offshore, predicting the future of beaches in the coming decades is extremely difficult.

Damaged houses at Collaroy Beach, Sydney in the wake of an extreme storm in June 2016. UNSW Water Research Laboratory, Author provided While extreme storms can cause major erosion to beachfront properties, they can also bring in new sand from deeper water. UNSW Water Research Laboratory, Author provided

Wave after wave

Violent storm waves strip beaches of sand above the waterline, which often erodes sand dunes. In deeper waters, however, these same waves help stir up sediment lying dormant on the seabed. This sand is then pushed towards the shore and settles as the storm passes.

To study the three storms in Australia, the UK and Mexico, we used high-resolution monitoring equipment including twin engine airplanes, drones and jet skis mounted with an echo-sounder for measuring the seabed.

The UK survey team measuring sand volumes along the coast of Cornwall. University of Plymouth, Author provided A combination of high-resolution survey equipment was used to measure changes to the beach. University of Plymouth, Author provided

In Australia, we measured Narrabeen Beach in Sydney. In the UK, we monitored the impact of several storms during the winters of 2013-2014[6] and 2015-2016, at Perranporth beach in Cornwall. And in northwest Mexico, we recorded the impact of the 2018-2019 winter on La Mision Beach.

In the time-lapse video below, you can see just how quickly the water can encroach on beachfront houses during extreme storms. Beneath the water surface, however, huge volumes of sand is also moving about.

imageA time-lapse of severe coastal erosion at Narrabeen-Collaroy Beach (SE Australia) during the June 2016 East Coast Low.Source: Mitchell Harley (author provided)

By capturing the three-dimensional seabed changes for each event, we could quantify for the first time the precise sand volumes mobilised during these extreme storms.

To give an indication of the scale of beach change, the amount of sand added to the beach resulting from the stormy periods was on the order of 100 cubic metres for every metre length of beach – that’s like 20 tip trucks pouring sand on every metre-wide strip.

Read more: The seas are coming for us in Kiribati. Will Australia rehome us?[7]

As the beaches spanned several kilometres, this amounted to 130,000 cubic metres for La Mision beach, 400,000 cubic metres for Narrabeen and 420,000 cubic metres for Perranporth.

The time-lapse video below is of Wamberal Beach during a storm in 2020. While it wasn’t included in our study, it’s another great example of how large storm waves cause abrupt changes to beaches.

Source: UNSW Water Research Laboratory (author provided)

Rethinking coastal erosion

Exactly how a coastline might change due to sea-level rise is a key question facing coastal managers, as they plan for the escalating impacts of climate change.

The Intergovernmental Panel for Climate Change projects[8] global sea levels to rise up to 76 centimetres by 2100, under a middle-of-the-road emissions scenario where global temperatures rise 2.1-3.5℃.

The response of the coast to sea-level rise has previously been estimated using an approach known as the Bruun rule. This rule states that for a given metre of sea-level rise, the coastline is expected to retreat between around 20m to over 100m, depending on the steepness of the coast[9].

UNSW researcher Chris Drummond launching a drone to survey the beach in Sydney. UNSW Research Laboratory, Author provided

Using the Bruun rule, global sea-level rise caused by climate change has been projected to[10] result in losing almost half the world’s sandy beaches by 2100. However, not all coastal scientists share this view[11].

Let there be no doubt: sea-level rise is a tragic consequence of climate change, and it poses an existential threat to many coastal communities, especially for island nations in the Pacific.

Mexico’s La Mision beach, on a calm day. In the winter of 2018-2019, research found that storms pushed 130,000 cubic metres of new sand into the beach system. Autonomous University of Baja California, Author provided

What our new research confirms is that the Bruun rule approach is overly simplistic, as it doesn’t take into account the many complex local factors[12] about how individual beaches respond to sea-level rise.

This includes the amount of sand stored in deeper water immediately off the coast, and its potential to replenish beaches during extreme weather events.

Understanding how sand moves along the coast is critical for better coastal planning. UNSW Water Research Laboratory, Author provided

Improving predictions in an uncertain future

While this research has focused only on three extreme storm sequences, it shows that understanding how sediment moves along the coast[13] is fundamental to planning for climate change impacts.

There are two ways we can significantly improve long-term predictions of coastal change in this uncertain future:

  1. upscaling efforts in mapping the seabed[14] to learn how much sediment is presently stored in the deeper coastal waters

  2. increasing routine coastal monitoring of the entire nearshore system, from the sand dunes down to deeper waters. This is currently carried out by UK coastal observatories[15].

A greater understanding of sand movements off the coast, combined with computer modelling, can better forecast future shorelines. This will give coastal managers the information needed to make critical long-term planning decisions for communities.

Read more: Why some beaches, including in Queensland, are getting bigger despite rising sea levels[16]

Read more https://theconversation.com/like-20-tip-trucks-pouring-sand-on-every-metre-wide-strip-how-extreme-storms-can-replenish-beaches-not-just-erode-them-182039

The Times Features

Why Regional Small Businesses in Bendigo Deserve Better Access to Finance in 2025

In the heart of regional Victoria, Bendigo has long stood as a beacon of innovation, resilience and community spirit. As we step further into 2025, the importance of nurturing sm...

Is It Time for a Deep Cleaning? Signs You Shouldn’t Ignore

Most people know they should visit the dentist for a regular check-up and cleaning every six months. But sometimes, a standard cleaning isn’t enough. When plaque and tartar build...

The Hidden Meaning Behind Popular Engagement Ring Cuts

When it comes to engagement rings, the cut of the diamond is not just about aesthetics. Each shape carries its own symbolism and significance, making it an important decision for...

Annual Health Exams in the Office: How They Can Reduce Sick Days and Healthcare Costs

Regular health check-ups, especially annual health exams in the office, can significantly impact the overall well-being of your workforce. A proactive approach to employee health...

Best Deals on Home Furniture Online

Key Highlights Discover the best deals on high-quality outdoor furniture online. Transform your outdoor space into a stylish and comfortable oasis. Explore a wide range of d...

Discover the Best Women's Jumpers for Every Season

Key Highlights Explore lightweight jumpers for spring and summer, ensuring breathability and ease. Wrap up warm with cozy wool jumpers for the chilly autumn and winter season...

Times Magazine

The Essential Guide to Transforming Office Spaces for Maximum Efficiency

Why Office Fitouts MatterA well-designed office can make all the difference in productivity, employee satisfaction, and client impressions. Businesses of all sizes are investing in updated office spaces to create environments that foster collaborat...

The A/B Testing Revolution: How AI Optimized Landing Pages Without Human Input

A/B testing was always integral to the web-based marketing world. Was there a button that converted better? Marketing could pit one against the other and see which option worked better. This was always through human observation, and over time, as d...

Using Countdown Timers in Email: Do They Really Increase Conversions?

In a world that's always on, where marketers are attempting to entice a subscriber and get them to convert on the same screen with one email, the power of urgency is sometimes the essential element needed. One of the most popular ways to create urg...

Types of Software Consultants

In today's technology-driven world, businesses often seek the expertise of software consultants to navigate complex software needs. There are several types of software consultants, including solution architects, project managers, and user experienc...

CWU Assistive Tech Hub is Changing Lives: Win a Free Rollator Walker This Easter!

🌟 Mobility. Independence. Community. All in One. This Easter, the CWU Assistive Tech Hub is pleased to support the Banyule community by giving away a rollator walker. The giveaway will take place during the Macleod Village Easter Egg Hunt & Ma...

"Eternal Nurture" by Cara Barilla: A Timeless Collection of Wisdom and Healing

Renowned Sydney-born author and educator Cara Barilla has released her latest book, Eternal Nurture, a profound collection of inspirational quotes designed to support mindfulness, emotional healing, and personal growth. With a deep commitment to ...

LayBy Shopping