ACT News


Updated maps to draw clearer picture of flood zones

ACT residents will soon be able to check online whether their homes lie within probable flood zones.

And new studies are underway to update flood maps for areas that lie close to creek systems and to assess the possible consequences of a ''cascade'' of dam failures in the northern suburbs.

The ACT government decided in 2011 that flood maps should be made publicly available. Following the updating of some maps, information will be progressively placed online from the end of the month.

Steve Forbes, manager of spatial services at the ACT Emergency Services Agency, said the results of a 2011 study of areas below a ''one in 100-year'' flood line would be the first to be published.

''It's for the Molonglo River Catchment from Oaks Estate through Lake Burley Griffin, over Scrivener Dam and then through the new Molonglo development area,'' Mr Forbes said.

Houses cannot be built below the one in 100-year flood line.


Money from recently announced federal grants would also be used to undertake a study to ensure resilience to flash and creek flooding.

The study would look at areas where updated information would be useful to flood planners.

''We're still putting a list together but some of the more critical ones we're looking at are Woolshed Creek, Sullivans Creek, Tuggeranong Creek and some of the tributaries that run through the Belconnen and Gungahlin areas as well,'' Mr Forbes said.

''We're trying to piece them together: a lot of the studies have been done at different times the years, some way back in the 1980s. We've come up with new science since then and we know more about the climate since then.''

Another study would use data from recent rainfall to assess the probable maximum flood from the failure of any or all of the Yerrabi, Gungahlin and Ginninderra dams - a possibility considered extremely unlikely by planners.

Jeremy Logan, the chairman of the ACT Flood Planning Committee, said good planning had ensured that Canberra generally had a low risk of major floods.

But he said it would still be useful to make the information more readily available to the public.

''It just gives you that sense of comfort,'' Mr Logan said.

''If you live in a house and you are within that one to 100-year flood line - which 99 per cent of houses in the ACT are not - you may consider what are your insurance options or whether you have a plan.

"Even last year when we had the heaviest rains in 50 years over those six days, the only places that were affected by the creeks and rivers backing up were some of the roads,'' he said. ''There were a lot of houses affected where there were systems [that] had backed up or drains were blocked up.''

Mr Logan said there were moves to abandon the term ''one in 100-year flood'', which referred to a 1 per cent probability of flooding occurring.

''If you live in Queensland, you might be tending to doubt that,'' he said.


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