Action needed amid flood concerns

Much of Southbank could be flooded today and action is needed to avoid more severe threats in the future, according to a report released to the public last month.

The report, entitled Port Phillip Bay Coastal Adaptations Pathways Project, is a hypothetical economic analysis of potential flooding at different points along the Port Phillip Bay coastline. It provides a framework for councils responding to flood threats.

It includes a specific case study on Southbank, warning of current flooding risks and also projecting to 2100, taking the effects of climate change into account.

The report details the economic effects of damage caused by flooding and outlines the most cost-effective time to act and type of remedial action required.

It also includes maps showing how vulnerable Southbank is to flooding, given our low-lying land.

The maps, and the report, are based on a hypothetical one-in-100-year rainfall event. They show that in 2011 (the year the report was commissioned) most of Southbank could have been inundated with up to 20 cms of water following such an event.

Without remedial action by 2100, more of Southbank would be covered and the depth would increase to potentially two metres in most areas after one of these storms.

The report stresses that, despite the high levels of potential flooding in Southbank, we shouldn’t be building our arks just yet. It says solutions are achievable and it outlines the most cost-effective actions to counteract the threat.

The report says waiting until 2040-2070 is the most cost-effective approach, as this is when the economic value of Southbank will be at its  greatest.

It says taking limited action between now and 2040 would also be cost-effective.

“Continued action should include improving both council and community awareness, preparedness and recovery from flood events and increasing resilience to additional larger events in the future,” the report states.

“Council should continue to progress actions to improve drainage in conjunction with Melbourne Water. This is expected to be the most cost-effective approach to reducing both current and future flood risks.”

The report also takes into account the central location of Southbank and its prominent state assets.

“Damage or loss of these assets will impact on key public services and amenity. While protection of these assets is beyond council’s responsibility, council should further consider how it can best support efforts to either improve the resilience of these assets to inundation or transition them out of the hazard zone.”

It also recommends close analysis of the Yarra River be undertaken.

“Further investigation of future river heights as a result of sea level rise and upstream rainfall should be undertaken.”

Southbank was one of five case studies in the report, which was compiled by AECOM for the Municipal Association of Victoria, the Association of Bayside Municipalities and the Central Coastal Board.

Much of the data collated on Southbank had to be researched by the report’s author’s themselves, given the radical change the area has undergone in the last two decades.

The reportcan be viewed online at www.abm.org.au/adaptationproject