EXPLAINER: In Australia, close to 1.4 million properties are at risk of flooding, according to the Insurance Council Australia.
The CSIRO says floods are the costliest natural disasters in Australia, averaging an $8.8 billion damage bill per year and the Australian Climate Service says after heatwaves, flooding is the second deadliest hazard.
Australians are told council flood maps are the source of truth about where flooding is likely to happen but trust in flood maps is under threat from competing pressures on local governments.
When updated flood maps are released, uproar often ensues as residents discover their properties are in flood zones. Many of those residents are starting to organise their opposition to council flood modelling.
The issue is peaking in Queensland: the state most at risk of flooding. Recently, an angry and organised group of residents successfully pressured Logan council to remove a worst case flood scenario from its new town plan.
Logan Ratepayers have a dedicated and highly organised lobby group for flood mapping
One flood risk expert told The Pineapple that staff responsible for flood mapping at Logan Council received death threats from irate residents.
Residents are less irate in the coastal tourist town of Noosa where flood maps show a large portion of the city under water in a 1 in 100 year flood event, but they are concerned about property values.
Noosa’s flood map shows Hastings Street underwater in a 1 in 100 year flood
Noosa Ratepayers Association President, Adrian Williams, said there were concerns about coastal hazards mapping in Noosa’s 2020 flood map affecting land values.
‘Coastal hazards mapping was a significant issue, with many submissions, particularly from coastal residents concerned about possible restrictions, excessive regulation and changes in land values,’ said Mr Williams.
IMAGE of the 1992 floods, corner of Gympie Terrace & Thomas Street supplied by Noosa libraries
However, he said the Noosa Ratepayers Association had confidence in council’s local knowledge combined with the state overview of flood mapping.
Lifting the hood on flood mapping
The good news is: multiple technical experts consulted by The Pineapple agree flood maps are scientifically rigorous, reliable and based on data agreed upon throughout the nation and the world.
The catch is: local government staff responsible for updating flood mapping present flood maps to councillors as flood risk models ranging from best case to ‘middle of the road’ to worst case.
Under the principle of subsidiarity (local authorities handle local issues), elected councillors are responsible for choosing which risk model to map for, so councillors with no technical expertise make that choice.
Most councils choose a risk level based on a 1 in 100 year flood event, also called the 1% AEP (Annual Exceedance Probability), based on past records. Given increasing record-breaking flood events across eastern Australia and rising rainfall intensity, some experts say past events are not the safest levels to plan for.
IMAGE of flood marker supplied by Gympie Regional Council
Dr Karen Palmer is a Sea Level Scientist at the University of Tasmania and an expert in coastal flooding. She will soon be releasing a dataset of future high tide levels around Australia, including worst case scenarios stemming from potentially abrupt changes in Antarctica.
Dr Palmer says councils choosing riverine or coastal flood mapping risk levels based on past events, or only allowing for modest future changes, ‘may not be taking the safest approach because we should prepare for the worst and hope for the best’.
Dr Karen Palmer is an expert on Sea Level Rise. IMAGE supplied
She says councils not having enough information, or a lack of ability to limit risky development, is a problem around the world.
Fears state govt guidelines watered down
One factor affecting councils’ ability to limit risky development is state government oversight because Queensland councils are guided by the State Planning Policy (SPP) requiring councils to consider climate change when producing flood maps.
Some flood mappers are concerned this may be watered down as the Queensland Government reviews the SPP. There are rumours the climate change consideration may be removed from flood mapping guidance policies.
Deputy Premier Jarrod Bleijie’s office did not answer questions about this specific possibility, stating:
‘The Crisafulli Government is currently reviewing the nine-year old State Planning Policy which guides flood risk assessments to ensure property rights are maintained and better planning outcomes are achieved.
‘We’re working closely with councils as part of the government’s reset of the planning partnership with local governments. Queenslanders can have their say when it is released for public consultation.’
Flood mapping ‘political’
The Climate Risk Group CEO, Karl Mallon, is a specialist in climate change impacts and risks to physical assets. He says climate change increases the risk of property damage by 25 per cent and must be factored into flood maps.
Karl Mallon is CEO of The Climate Risk Group. IMAGE supplied.
Mr Mallon says ‘political’ decisions about the flood risk models chosen in flood maps means ‘some councils are not choosing a forewarned is forearmed approach’.
‘Flood maps are political in some ways because when an area is designated as a flood zone, it will affect property values and insurance costs. We’ve seen instances where flood maps have been destroyed because the elected officials didn’t want to proceed.’
Mr Mallon says not only should climate change be factored into flood mapping, but mappers should be wary of mapping only for low climate emission scenarios.
‘A big emerging issue is what climate scenario do we model to and we’re seeing a watering down. People are saying we shouldn’t look at high emission scenarios because they are unlikely to occur. A lot of the floods and fires we’re seeing now are worse than predicted so we may be under-predicting risk.
‘It’s a very poor approach to risk management to assume the best. It’s like saying I’m not going to put my seat belt on today because I don’t think I’m going to have a crash.’
Calls for state and fed govts to step up
Local governments are responsible for factoring climate change into flood mapping and a common call from climate change experts and insurers is for this responsibility to be shared more equally between local, state and federal governments.
A recent paper published by Monash University academics Elham Kazeminia and Colette Mortreux argues for integrated governance models and coordinated policies, so Australia can better adapt to climate change and coastal hazards.
Dr Mortreaux said residents often struggled to understand the scientific rigour behind flood mapping. She said local governments were not always confident state governments would back councils’ interpretations and applications of flood modelling.
‘There’s a delicate tension between local, state and federal governments. There is enormous pressure on local governments with low resources to manage flood mapping fallout,’ Dr Mortreaux said.
‘Often there is no clear state government recognition of this issue and local governments have to advocate for themselves.’
Insurers want better flood mapping
The Insurance Council of Australia (ICA) has also called for a more integrated approach between the three levels of government and for better, more consistent flood mapping.
In its Advancing Australia’s Resilience report, released last year, the ICA called for more federal government investment in flood mapping, saying:
‘…flood remains Australia’s most costly and rapidly growing extreme weather risk. Understanding the nature and extent of flood risk is important to residents, local councils and first responders, given the material risk to life and property damage.’
Calls for national flood maps
Currently Australian flood maps are a mosaic of very different looking maps created by local governments, water corporations and insurers, all using differing methods to calculate and communicate flood risk.
The Climate Risk Group’s Karl Mallon says there’s been discussion of a national flood map for over a decade but the Commonwealth instead opted to assemble directories to council flood maps.
‘It was a wasted opportunity,’ said Mr Mallon, whose company instead pays commercial organisations for private flood maps. ‘There are no government owned national flood maps of Australia,’ he said.
Insurers have added their voice to experts calling for Australia to build a national flood map database accessible to households similar to those used in the US, the UK and the Netherlands.
The Netherlands has a free, easy to navigate national flood database available to households and industry
‘A robust, national hazard database that streamlines existing national, state and territory datasets and is accessible to all levels of government, industry and the public is crucial for improving understanding of climate risk,’ the ICA said.
The peak body says the federal government should also ‘provide funding to support local government hazard mapping updates, including flood mapping, to provide more certainty for insurers, accuracy for premium pricing and improve community awareness of risk.’
The ICA also says state and local governments should stop approving development in areas at risk of flood: a policy Lismore Council has already committed to.
Push for housing could mean approvals in flood-prone areas
In Queensland, the Crusafulli Government has been open about its development agenda. When it’s released, Queensland’s new State Planning Policy will be scrutinised for signs the government is watering down development controls to fast-track housing.
IMAGE of housing estate by Eric Brehm
The ICA’s report says the opposite is needed.
‘As the population increases, the pressure for new houses to be built in higher risk areas will grow … the lowest cost option will often be for these homes to be built in higher risk areas, putting more people in harm’s way, increasing the cost of future disasters and putting upward pressure on premiums for all policyholders.’
One respected Queensland flood risk management expert, who preferred not to be named, said the biggest issue in flood mapping was pressure from the housing market.
‘We are seeing state and local governments potentially looking to water down planning policies to allow housing,’ he said.
‘There’s also a lack of clear guidance for councils on which flood scenarios they should model for. This could be putting housing and people in harm’s way.’
Fed govt ‘playing its part’
The Pineapple sought comment from the Federal Minister for Emergency Management, Kirsty McBain, about calls to make flood mapping more integrated and consistent between local, state and federal governments. The minister’s office did not answer that specific question though a spokesperson said:
‘While state and territory governments rightly have primary responsibility for preparing for disasters, including hazard management initiatives such as flood mapping – ensuring that disaster mitigation activities address the specific needs of communities – the Australian Government is playing its part, including:
- providing mapping on the Australian Climate Service website – which can be filtered by LGA insights, and
- developing the free online Climate Risk Digital Tool enabling councils to work through a risk assessment step‑by-step and making available the Local Government Climate Risk Guide.’
The Australian Climate Service Website mentioned above is not a national flood map but provides general data about natural hazards and climate change. The Climate Risk Digital Tool is only available to public sector employees.
The Pineapple did not receive responses to requests for comment on flood mapping from Noosa, Gympie or Logan Councils. Floodplain Management Australia said ‘it was not able’ to comment. No flood mappers were willing to speak on the record.
CARTOON at top of story by Matt Mawson.
This article was funded by the Local and Independent News Association (LINA) and supported by the Constructive Institute Asia Pacific Hub.
