What lessons have we learnt from the Lismore floods?
MORE UNDERSTANDING OF FLOODS
HEIGHT data obtained from the March 31 flood will be used in new flood modelling to hopefully spare Lismore from the worst impacts of the next extreme flood.
Rous County Council consultant engineer and Lismore City councillor Bill Moorhouse said markers of the various flood peaks around Lismore, upstream and downstream were invaluable to understanding the event.
"We've got all those points and we're going to put those into a computer model that's being refined at the moment," Cr Moorhouse said.
It takes several days to run the flood model through a sophisticated computer program, which factors in every square metre of topographical information available in the catchment.
But most of the previous data used for modelling was collected after the 1989 flood, using old computers and "average" ground information.
Now the data is laser measured precisely - and is already providing valuable new insights.
The updated model will prove useful to determining whether options such as a higher levee could prove decisive in avoiding another disaster.
Cr Moorhouse said the models would provide some good ideas within three to six months.
Rous County Council is spending about $100,000 bi-annually on flood modelling for the Wilsons catchment.
Southern Cross University is also actively assessing how it can increase understanding of Lismore's major flood events.
Okay everyone, this weekend volunteers are needed! Put on your boots, long pants and work gloves, and head on... https://t.co/3IvihYe2Jh— Lismore City Council (@LismoreCouncil) April 7, 2017
DO WE RAISE THE LEVEE?
The most obvious step to protecting Lismore might be simply to raise the levee by at least 50cm.
Cr Moorhouse said this could be the simplest solution to reducing the worst effects of a big flood.
He said he would like to think the levee might be raised within two years, but "we'll have to prove that it's right".
But, he noted, "there were still people last time who wanted to oppose it".
It actually took a decade after the 1989 flood when a broad consensus was reached before construction started on the levee, which then took another five years to build.
EUROPEAN settlement hashad a dramatic effect on how the Lismore floodplain is inundated, and reversing one of those effects could prevent more devastating floods.
Recent modelling has shown floodwater from Leycester Creek naturally seeks to overflow west of the CBD and South Lismore in a southerly direction, before linking up with the Wilsons River .
Unfortunately, it is being constrained by the 'unintentional levee' of the raised east-west rail line parallel to Kyogle Rd that effectively directs more water over the South Lismore levee in flood.
Finding a way to get more flood water running to the west of Lismore could be one of the solutions to mitigating impacts on the town.
A floodway west of Lismore might help, but a large-scale one was proven too expensive and not worth the investment.
However there may be more cost-effective ways of diverting at least some of the flow into the city centre.
"What we need to do is get more water down where it should ago and where it wants to go down past the airport," said Cr Moorhouse.
COMPLACENCY AND BETTER PLANNING
COMMUNITY leaders, business owners and residents have begun to put their heads together to improve flood management.
Lismore Mayor Isaac Smith aims to implement mandatory flood preparedness and recovery plans for every Lismore resident and business.
"I don't think the previous measures that were funded by the State Government around seminars and voluntary meetings is enough, we need to make sure that everybody has these plans in place," Cr Smith said.
One of Lismore's volunteer hub coordinator, Robyn Kelly said support services shouldn't be left to social media initiatives like the Lismore Helping Hands.
"I'd like to see the State and Federal Government standing by their local councils and ensure they get the right funding and services immediately in place," Ms Kelly said.
The language used in SES public flood warnings may be a factor to evaluate after confusion about terminologies was highlighted by the SES at a Lismore flood forum last Thursday.
SES representative, Janet Pettit cited on-going confusion about the meaning of a flood evacuation order and watch at the meeting.
Commander Superintendent Greg Martin said the wording may not resonate with a "reasonable citizen who has no emergency management training."
He didn't rule out assessing public warnings as emergency services start to reviews into flood management.