Cheryl Desha, Griffith University

Thousands of residents are mopping up in the wake of ex-Cyclone Alfred, which has damaged homes and cars, flooded roads and gouged out beaches.

I write from Brisbane, where rain has fallen for several days. Most of it is draining to a coastline already swollen and eroded by Alfred’s swell.

Flood warnings are current in southeast Queensland and northeast New South Wales. Many communities are in danger – some of which have faced multiple floods in recent years.

Despite all this, the damage could have been so much worse – and we may not be so lucky next time. Australia must use Cyclone Alfred as a serious wake-up call to bolster our essential infrastructure against disasters.

A complex picture

Cyclones are incredibly complex. They involve multiple interacting hazards such as severe wind, flooding, storm surge and erosion. This makes their impacts hard to predict.

Alfred meandered slowly off the coast for almost a fortnight, fed by warm waters in the Coral Sea. Its movements were made even more complicated by a new moon, which creates extra-high high tides.

Despite these intricacies, experts were able to map the path and character of the cyclone. This was due to collaboration between multiple agencies and personnel across national, state and local governments.

This information was quickly transmitted to the public via local government emergency dashboards, apps and emergency radio broadcasts, as well as traditional media. The warnings meant communities knew what was coming and could prepare accordingly.

However, Alfred’s force exposed major weaknesses in vital infrastructure.

Electricity outages reached record levels, peaking at more than 300,000 across both states. Queensland Premier David Crisafulli described the outages as that state’s “largest ever loss of power” from a natural hazard.

On the Gold Coast, residents of newly built luxury apartments reported rain penetrating past windows and into homes many storeys above the ground.

Falling trees crushed homes and cars, and in at least one case sparked an electrical fire.

In Queensland and NSW, Alfred flooded and damaged roads, causing scores of road closures and traffic signal outages.

Drawing lessons from nature

As climate change worsens, extreme weather will become more frequent and severe. We must minimise the risks of infrastructure failing during these events. It will require a broad range of measures extending beyond those adopted in the past.

Nature is incredibly resilient. It can offer many lessons to decision-makers, engineers, town planners and others. This approach is known as “biomimicry” – innovation that emulates the forms, processes or systems found in nature.

Connected vegetation such as a line of mature trees, wetlands and mangroves can detain and slow water. This means water passing through has less energy to erode land and topple infrastructure. It also allows for water to soak into the ground, which cleans it and filters out debris.

In flood management, holding ponds known as “detention basins” are used to temporarily store stormwater run-off during heavy rain. City parks can be reshaped or upgraded to become detention basins, holding water until it can safely drain away.

Urban infrastructure could also mimic the swales and earthen mounds found in nature, by incorporating human-made channels and mounds. These would guide water away from communities and infrastructure, to storage above or underground.

And what about our coastlines? Cyclones stir up huge swells which crash on shores and gouge out beaches. Alfred has left extreme sand erosion up and down the coast.

Coastlines are inherently mobile; sand naturally leaves and returns, depending on the weather. To protect our permanent coastal development, sand dune restoration could provide a line of defence in front of built infrastructure. This option has been implemented in the Netherlands, where it was found to be cost-effective.

In Australia, an estimated 17% of mangroves have been destroyed since European settlement. Mangroves naturally buffer the land from wind and storm surge. Reinstating mangroves could help protect coastal communities from future wind damage, as a 2020 study in Fiji showed.

Globally, there is a growing movement towards creating “sponge cities”. These are urban areas rich in natural features such as trees, lakes and parks, which can absorb rain (and sometimes wind) and prevent flooding.

Australia is cottoning on to how nature can help protect our cities. But there is much more work to do.

Experts from James Cook University have been deployed to southeast Queensland to capture immediate data after ex-Cyclone Alfred. They are documenting the effects of extreme wind and other hazards on buildings and infrastructure, and collecting data on wind speeds, water ingress and damage caused by debris.

Hopefully, the findings will inform decision-making on construction, building codes and disaster-resilience strategies for communities.

Building back better

Climate change is expected to cause fewer, but generally more severe, tropical cyclones. Combined with other climate-related changes, such as more intense rainfall and higher sea levels, the risk of flooding associated with cyclones will worsen.

Significant money is already being spent on disaster prevention and preparedness. However, more is needed.

Australians should not need another reminder to proactively reduce the damage caused by extreme weather events. But Alfred has certainly provided one.

As the clean up begins, let’s embrace the opportunity to build back better.

Image: Envato

Cheryl Desha, Visiting Professor, School of Engineering and Built Environment, Sciences Group, Griffith University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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