Floods in Sydney | The climate crisis in action

The city of Sydney, Australia, has been experiencing very severe flooding for four days, prompting thousands of residents to evacuate their homes. A recurring phenomenon in recent years that raises questions about the adaptation of the public sector to one of the concrete consequences of climate change.

Posted at 6:00 am
Updated at 6:48 am

Vincent Marcellin

Vincent Marcellin
The press

How bad is the damage?

After four days of torrential rain, the country’s most populous city is grappling with one of the worst flooding in modern history. Water rose to more than 16m along the Hawkesbury and Nepean rivers on Sunday morning. The floods also caused the Warragamba Dam, which supplies drinking water to most of the city, to overflow. “Some locations have received more than 600 millimeters of rain in two days, or about half the annual rainfall,” Kimberley Reid, an atmospheric scientist at Melbourne’s Monash University, said in an interview with La Presse.

On Wednesday morning (Montreal Tuesday), the New South Wales State Emergency Service in Sydney reported that 6,410 requests for assistance have been received since the weather phenomenon began last week, including 304 flood-related rescue operations. The day before, authorities had called on around 50,000 people to evacuate and 28,000 to prepare.

The federal government has declared natural disaster status in 23 flooded areas of New South Wales and released aid to those affected.

How can the increase in such floods be explained?

This event is far from the first in Sydney, which has been regularly hit by flooding in recent years. In March, one of them killed 20 people and caused the evacuation of 60,000 people. “The floods of the past 18 months have broken records. This year is the wettest,” says Kimberley Reid.

In an article published on The Conversation Australia, Dale Dominey-Howes, Professor of Risk and Disaster Risk at the University of Sydney, offers three main explanations for the increase in these phenomena. First the geography: the Hawkesbury and Nepean rivers cross a very narrow ‘pinch point’ which slows the flow and increases the risk of flooding. In addition, with population growth and housing affordability crises, many homes were built in flood-prone areas. Finally, the expert underlines the lack of preparation by the New South Wales government, which he believes should have predicted the risk of flooding better.

An observation shared by Kimberley Reid, who insists on the responsibility of public authorities in this crisis: “The government authorized the construction of buildings in the flooded areas, fully aware that flooding was frequent in these places . »

What connections can be made between these floods and climate change?

Flooding is one of the visible consequences of climate change in Australia. For Florent Barbecot, professor in the Department of Natural Sciences and Atmosphere at UQAM and specialist in water management issues, the impact of global warming on precipitation plays out on two levels. “The higher the global temperature, the more water vapor the atmosphere can hold. This water vapor may fall in the form of rain,” explains the researcher.

But global warming is also having an impact at the local level. “Once we start urbanizing an area, it rains less but more intensely. This amplifies the global phenomenon, and ultimately we create more and more hostile environments,” says Mr Barbecot.

How to deal with this situation?

In Sydney, Kimberley Reid sees land use planning as a priority for flood control. “We really need to think about what kind of housing developments we build to include a lot more green space. This is how the soil and plants absorb water when it rains. »

Florent Barbecot also insists on the need to anticipate these problems. “In Sydney, authorities were surprised because the dam was filling up much faster than expected. If there had been a development beforehand, the filling could have been delayed,” he explains.

The researcher is convinced that there are solutions to avoid such natural disasters. “Today we can say what kind of developments can limit the effects of global warming at the local level. We must prepare for the worst. It is clear that it will be very expensive for our society because the population is growing and we know that urbanization will spread. Cities will therefore play an important role in the occurrence of flood episodes,” the researcher concludes.

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  • 733mm
    Measured rainfall in Sydney between Friday and Monday. For comparison, the City of London receives an average of 615mm of rain per year.

    Source: BBC News

    Number of requests for assistance received by the New South Wales State Emergency Service on July 6th

    SOURCE: NSW his

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