Flooding is a natural process caused by heavy rainfall. It has helped to shape the landscape around us, the creeks and swamps, and the floodplain on which much of Newcastle has been developed.
Flooding is generally a rare event but will continue to happen into the future. It is not possible to predict when, where, or how big the next flood will be. We can, however, estimate the likelihood of different sizes of floods.
There is actually no such thing as a '100 year flood'. Each flood is different. On average, larger floods are rarer than smaller floods and the chance of a certain size flood happening in any given year is the same each year, even if a flood occurred the year before.
The largest flood that could occur is called the Probable Maximum Flood. Newcastle has not experienced such a flood in the last two hundred years.
The impact of heavy rain will act differently in different catchment areas. In large catchments including the Hunter, it takes a long time for widespread rainfall to 'fill' the catchment and come down the river.
In smaller catchments, including most of Newcastle's suburbs, it only takes a short time for rainfall to 'rush' down the catchment and overwhelm drainage systems causing localised flooding.
(click on map to download larger pdf document) 82 kb PDF*
The blue areas on the map could flood in the future. Surprisingly many of these areas are in the suburbs are away from the Hunter River Floodplain.
There are many complex issues surrounding flooding in Newcastle including:
Investigations so far…
It is critical that flood management decisions are based on realistic understanding of all possible future flooding in Newcastle.
Computer simulations of future flooding are being developed across the city. These simulations are based on the best available information of rain that can occur, tide and ocean levels, and accurate ground levels. Simulations are checked against records of previous flooding in Newcastle.
Newcastle City Council is developing solutions to manage Newcastle's complex flooding problems with substantial grant assistance from the NSW Government.
The Council's Flood Risk Management Committee is developing strategies and action plans to live with the risks in a way that balance environmental, social and economic issues.
The committee includes Council, community and government representatives and it is taking an overall approach that :