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Portal brings flood risk research into residents’ homes

Flood watch: Goulburn Broken Catchment Management Authority’s Guy Tierney is as informed about Shepparton’s flood risk as anyone. Photo by Murray Silby
Historical record: This marker on the Goulburn River at Daintons Bridge in Shepparton shows what can happen when the region floods. Photo by Murray Silby

When the Climate Council recently pronounced that more than 90 per cent of homes in City of Greater Shepparton might be uninsurable by 2030 due to the impacts of climate change, it threw into sharp focus the measures being taken to protect the city’s residents.

At the time, Greater Shepparton City Council acknowledged it is concerned climate change will have an impact on the municipality and emphasised the important part flood mapping will play in the region’s defence.

Riverine flooding was listed by the Climate Council as the region’s major threat, given it is basically one big flood plain and, for Shepparton and Mooroopna in particular, as they are positioned on the Goulburn River where the Broken River and Seven Creeks converge.

In the field of predicting riverine flooding, the Goulburn Broken Catchment Management Authority is a key contributor, monitoring the movement of water across the flood plain and down the river and creek systems, as well as advising local governments on matters relating to emergency management and development proposals.

The Goulburn Broken Catchment Management Authority’s partnership with local government has extended beyond City of Greater Shepparton to include five other municipalities — Benalla Rural City, as well as Moira, Strathbogie, Mitchell and Murrindindi shires — in the Goulburn Broken Community Flood Intelligence Portal.

The portal is a website through which residents could evaluate the flood risk for their property, which could be used to strengthen their case for a reduced insurance premium to predict their vulnerability under specific flood scenarios.

Goulburn Broken CMA's statutory planning and floodplain management manager Guy Tierney said the portal provided residents with access to the science authorities used so they could make more informed personal decisions.

“One of our prime objectives is to make as much flood intelligence available to the community for self-help,” he said.

“You should be able to navigate across many floodplains, you can zoom in, pan around and select flood maps for range or gauge heights, or what we call design events — one in five, one in 20, one in 50, one in 100 (years) etc and some of them do have historical extents — 1993, 1974 floods, and so you can type your address in or pan to where you live.

“You can click on ‘property report’ and in that it gives you a flood preparedness table and it tells you at what gauge height you might get over-floor flooding or not.

“What we expect with people a bit concerned about insurances, I can’t comment on how companies price, but if you demonstrate your floor level is well above one per cent or above the one in 50 year, I expect it should have some weight on pricing in insurance,” Mr Tierney said.

There have been multiple flood studies carried out over the decades for Shepparton based on research and records, but in particular a recent study used LiDAR or laser scanning, which not only takes into account natural terrain, but also constructed features such as roadways, railways, irrigation channels and bridges.

The Goulburn Broken CMA is predicting climate change to bring increases in average flood levels of between 150mm and 200mm across the Shepparton, Mooroopna and Kialla area.

“I guess the blessing for Shepp-Mooroopna or the northern floodplains, where we live north of the Great Divide, these flat, wide floodplains, it means for every centimetre of rise it means a lot more flow because the water spreads out wide,” Mr Tierney said.

“We’re not in a confined valley like Lismore (in NSW) where it’s very sensitive to flow.”

The Goulburn Broken Community Flood Intelligence portal can be found at my.floodreport.com.au/gbcma