As the costs of the response, recovery and rebuild of the past week’s devastating floods add up, commentators have begun to ask how we can build back better – we believe this time, building back better may mean building back somewhere else.

Several thousand people have been evacuated in western Sydney over the past week, with the downpour leaving communities isolated, submerged roads, and forcing schools to close. As the weather clears, they are returning to pick up the pieces of flood affected homes and businesses, and coming to terms with the emotional and financial realities of recovering from a disaster.

The bill will be enormous. The insured costs of the areas affected in western Sydney are not available yet, but it will likely be most of the estimated $2 billion statewide insurance bill.

Then there’s the uninsured costs. Over the past decade, insurers have improved their ability to assess the risk of specific households, which means pricing risk more highly for those most at-risk. That means much higher insurance costs for many in the floodplain. Anecdotally, many have given up.

This leaves the government, as insurer of last resort, with the bill for large scale deployment of emergency services, defence forces and longer-term relief and recovery support.

The final cost will be in the billions of dollars. As residents, businesses and governments face the stark reality of rebuilding and reestablishing homes, farms and businesses in this increasingly hazard prone location, we have an opportunity to use that money differently to support Western Sydney residents and businesses for the long term.

Raising the dam wall has been put forward as a way to mitigate the impact of future flooding. But a report from the NSW State Emergency Service last year laid out why floods in this area tend to be so large, deep and dangerous, and how a 1 in 100 year flood event would require 55,000 people to evacuate. While a raised dam would prevent more minor flooding, we also know that it would not prevent the major flood events like what we saw last week.

If nothing is done to address this escalating risk from extreme weather and climate change, by 2100 Sydney will have a projected 91,000 ‘uninsurable’ addresses — the most of any city — with over five times as many uninsurable properties in 2100 than in 2019. The most ‘uninsurable’ areas will be concentrated near the Georges River in the south-west, the Hawkesbury River to the north and the Nepean River in the west.

In Norfolk, Virginia, the city’s response to sinking into the sea has been to take a long-term approach to gradually shift development away from the places that will be flooded. They created a ‘traffic-light’ overlay of the city that groups places into green, yellow and red zones based on risk for future flooding. New growth is directed into areas of low risk, and there are incentives to gradually shift development away from the places that will be impossible to protect in the future. In effect, it is a road map for promoting future development out of harm’s way where possible.

Closer to home, the 2011 Queensland floods affected over 38,000 residents and businesses with an insured cost of $1.5 billion, including around 20,000 households and businesses in Brisbane. To break the cycle of disaster and recovery, Brisbane City Council introduced a Voluntary Home Purchase Scheme, purchasing $35 million worth of flood-affected land once shared between 73 private property owners across Brisbane, transforming the land into parklands, green space, conservation areas or green links to bikeways.

These case studies give us models that could help navigate this complex question:

• Create a Norfolk style map of the floodplain identifying areas of high, medium and low risk, and a long-term vision for reducing the risk to life and property across the floodplain. Led by local government and agencies like the Western Parklands City Authority and Resilience NSW, this vision would identify a pathway to reducing existing risk hotspots, identify where evacuation infrastructure needs to be enhanced, and replace planned development in the floodplain with opportunities to re-establish market gardens and recreation uses.
• Introduce ‘transferable development rights’ style approach to land on floodplain.This approach would build on the Norfolk style map to help each local government area identify where increased density would be acceptable – in areas of the floodplain where development was targeted for reduction, developers could buy existing residential lots and transfer that development potential (or existing use). Effectively this mechanism would act, over time, to redirect development from areas of high risk to areas of low risk and planned growth.
• Establish a voluntary purchasing scheme that supports residents to move out of the way of the floods.Scaling back development in the floodplain would move people out of harm’s way and reduce growing pressure on our emergency services agencies. Funded by state government, this scheme would provide a mechanism for residents to sell flood risk properties to the government at market rates, transferring ownership into Landcom or Western Sydney Parklands Authority to be managed consistent with designated land uses.
• Strengthen evacuation infrastructure.Unlike Norfolk, we know there is no practical means to protect existing building structures in the Hawkesbury-Nepean floodplain against damage from either water depth or velocity in severe floods. We need evacuation routes to reduce risk to life and increase the time for people to leave, recognising this is purely a safety measure for existing populations rather than an enabler of additional development potential.

Regardless of what Sydney decides to do, the question before Western Sydney is this: do we really want to continue to put people in the flood plain? Previous governments ignored the science, hoping it would be all right. The result has been tragedy for thousands of people.

The recent floods should make it clear it is not responsible to put people where they will be exposed to this level of harm.

It’s time for Sydney to look at a long-term plan to reduce the cycle of disaster, response and recovery that continues to test the safety and resilience of at-risk communities and stretch the resources of our emergency management agencies.