NSW floods: Sydney basin will always take in water
The 33 council areas in the Sydney basin are among the worst affected by flooding. We are always going to take in large volumes water in the future, according the experts. It is uo to authorities and planners to best manage this reality.
BY its sheer volume of land lots the great Sydney metropolitan area, made up of 33 local government areas, has the greatest number of properties prone to flooding.
Groundsure’s ClimateIndex deems 21,221 properties under high risk of flooding right now. This represents 1.7 per cent of its total 1.2million blocks.
Three decades on the situation will change little despite mitigation strategies planned or already in play.
By 2053, 21,415 land lots in the Sydney metropolitan area face a high risk of flood.
But the biggest mover in terms of increased threat of flood inundation is the Central Coast region, just an hour’s drive north of the harbour city.
The Central Coast LGA, currently ranked fourth with 9.5 per cent of its properties at high risk of flooding will find a further 561 of its properties facing inundation (10 per cent). Its change is the biggest shift in terms of volume increase.
In recent years the Central Coast has been subject to other devasting forces of nature such as extreme coastal erosion in beachside suburbs such as Wamberal and Terrigal.
According to Groundsure researchers, flood-prone areas of the state will most likely stay that way well into the future.
The amount of water – flood levels – will become worse as weather patterns take hold in the next three decades, they warn.
The Central’s Coast proximity to Sydney, and its improved highways and rail services, make it a desired place to live for those prepared to take the hour-long commute south.
The Narrabri region in the NSW north west, and home to broad acre cotton plantations, need good water supply to feed that industry.
Fifty-seven per cent of its properties face a high risk of flooding now – 8,134 land lots. Over the next 30 years, the ClimateIndex predicts that just one more block of land in the area will be at high risk of being overwhelmed by rising waters. Still, a large per centage of the region’s total land lots (57.9 per cent).
Climate Data used for flooding predictions
The key source of climate data is the CORDEX (Coordinated Regional Downscaling EXperiment) Region 9: Australasia from the World Climate Research Programme (WCRP). The key adjustments relate to precipitation (fluvial and pluvial) and sea level rise (tidal).
An ‘adjusted baseline’ was then calculated for peak river flows, rainfall volume and storm-surge peak from the CORDEX climate data and/or prevailing government policy guidance.
