“The five-paragraph letter to Lismore City Council was short, dismissive.
The [NSW] Department of Planning and Environment was rejecting the council’s application for a $100,000 grant to improve its flood warning system. The proposed works - new rainfall and river height gauges, CCTV cameras and a “community flood dashboard” - were deemed “premature”.
Three days later, on February 28, the biggest flood in modern Australian history inundated Lismore, and the rest of the Northern Rivers.” [The Sydney Morning Herald, 30 June 2022]
The rainfall event that triggered the 22 February to 15 March 2022 Northern Rivers Flood reached its maximum intensity in less than 24 hours and, 41 climate gauge stations (out of the 108 active climate gauge stations covering the river basins about to flood) as well as 8 flood gauge stations (out of 86 active flood gauge stations covering those same basins) had already or were about to fail.
The most critical of these active station failures occurred in the Richmond, Tweed and Brunswick basins. While the absence of stations in sections of a number of highly variable flow river catchments & sub-catchments, along with the restricted form of official rainfall recording (9am to 9am), meant that blind spots were already built into the flood watch systems operating in the Northern Rivers region.
IMAGES: CSIRO (30 Nov 2022) Lerat, J. et al, “Characterisation of the 2022 floods in the Northern Rivers region”, pp. 2 & 15] Click on images to enlarge
MSM, 23 February 2023:
Warning systems will not be immediately improved under a $50 million plan to better protect the Northern Rivers from floods, despite a scathing CSIRO report finding an urgent need for a better system.
The report released today revealed for the first time the extent of failures in the state’s flood warning system during the February-March floods last year, which killed four people and left thousands of people stranded on their rooftops.
It also recommended the development of a comprehensive flood warning network, as revealed in the Herald this morning, but the government has not included this work in the first stage of projects to be funded on the back of the report. Another $100 million of projects are yet to be announced.
The report found the warning system failures in the Northern Rivers last year had “critical consequences”. They led to river heights being “severely underestimated” and “severely impacted” warning times.
The Wilsons River in Lismore peaked more than three metres higher than initially predicted by the Bureau of Meteorology on February 28 last year, catching the State Emergency Service and other emergency services off guard.
Towns downstream were also devastated over the following days, including Coraki, which was cut off for five days until the army was able to gain access on March 6.
The report, released on Thursday by federal emergency management minister Murray Watt, found that more than 50 gauges that measure rainfall and river heights failed in the Northern Rivers during the February and March floods.
Gaps in the network also meant the authorities did not realise how much rain was falling in some areas, or how high the rivers were running during the event.
“There is an urgent need for more rainfall and river height data to feed BOM’s predictive models and enable SES to disseminate appropriate warnings,” the report said.
“[Gauge failure] has major consequences for providing early warnings during a large flood event.”
Watt released the report in Lismore and outlined the first list of flood mitigation projects to be funded.
The list of projects includes almost $30 million to improve flood pumps in Lismore, $3 million to increase community flood risk awareness, and $3 million to support community-led resilience initiatives.
The state’s rain and river gauges, which inform flood predictions and warnings, are owned by four different government entities.
The CSIRO found this created issues around accountability when they malfunctioned.
“Whilst the cause of each gauge failure is yet to be determined, consistent maintenance of rain and river height gauges is likely to reduce the risk of gauge failure in future flood events,” it said.
“It is recommended that the failures are investigated and equipment is strengthened for future flood events.”
The report identified some of the key failures, including a key rain gauge in the Lismore hinterland that recorded a zero reading throughout the event, despite torrential rain.
“Even if it were functioning properly, it would have recorded an inaccurate reading as it is poorly placed under an overhanging tree,” the report said.
There was also a lack of gauges around Terania Creek, to the north of Lismore, which recorded some of the highest rainfall during the event.
This is despite the fact that, according to the Lismore flood plan, the two previous highest floods in Lismore – in 1954 and 1974 – were associated with very high rainfall over Terania Creek.
This lack of gauges “contributed to the underestimation of the flood peak at Lismore”, while a “lack of gauges in Bungawalbin catchment severely impacted warning times for towns downstream”.
The Sydney Morning Herald, 23 February 2023:
SES Commissioner Carlene York says the flood warning system for Lismore and the Northern Rivers remains inadequate, one year after a record-breaking disaster killed four people and left thousands homeless.
“It’s not a satisfactory situation, put it that way,” she told The Sydney Morning Herald, agreeing that gaps in the region’s network of rain and river gauges left the city vulnerable.
“Just as we have road traffic cameras so we can see what’s happening on the roads, from the SES point-of-view, we really want these gauges to give us timely information about what’s happening upstream so we can forecast the effects,” York said…..
Since the flood, the SES has permanently positioned five more boats in the Northern Rivers, as well as a high-clearance vehicle that can drive through floodwaters…..
State Labor MP for Lismore Janelle Saffin said the Northern Rivers gauge network should be the first fixed under the $15 million program.
“It needs to be done sooner rather than later,” she said. “I’ve asked that question of senior [state] government – if, God forbid, the 28th of February happened again, what’s the plan?
“I’d like it to be quicker on the gauges. I’m not sure it can be, but I’d certainly like it to be quicker than June 2025.”…..
Lismore Citizens Flood Review Group co-ordinator Beth Trevan said Lismore was still “very vulnerable” to flood and more needed to be done to protect the city.
She said it was worrying it could take another two years to improve the gauge network, but residents upstream were already able to provide information to warn the community before a flood – only SES headquarters did not know how to use it.
“It worries me, as [the SES] take no notice what people in upper reaches are telling them,” she said.
“As long as they’re relying on the BOM and the time it takes for the BOM to get the information from the gauges and put it through their computer systems, it’s never going to work. They need to go back to people.”
The CSIRO report also noted the value of information from property owners upstream…..
NOTE:
CSIRO 30 Nov 2022 report prepared for the National Emergency Management Agency, "Characterisation of the 2022 floods in the Northern Rivers region" can be found at: https://nema.gov.au/sites/default/files/inline-files/Characterisation%20of%20the%202022%20floods%20in%20the%20Northern%20Rivers%20region.pdf
and
CSIRO 30 Nov 2022 report prepared for the National Emergency Management Agency, "Rapid Project Prioritisation for Flood Resilience in the Northern Rivers region" can be found at: https://nema.gov.au/sites/default/files/inline-files/Rapid%20Prioritisation%20for%20Flood%20Resilience%20in%20the%20Northern%20Rivers%20region.pdf
Remembering......
In the little town of Yamba on the Clarence Coast section of the Northern Rivers region we watched in disbelief and horror at what was unfolding to the north of us on the afternoon, evening and night of 28 February 2022 and what first light brought into view on 1 March.
Whilst at the same time in the 24 hours up to 9am on 28 February 274.4mm of rain fell on Yamba township and continued to fall with another 258.2mm up to 9am on 1 March - initially driven by winds gusting up to 81km per hour - before the rain cell shifted position.
This resulted in a mixture of river water and stormwater entering streets and/or properties it had either never entered before or had previously entered at lower water heights. All of which was exacerbated by flood waters still travelling down the Clarence River into the tidal estuary system.
Active climate gauge and flood gauge station failures were not a feature of the town's surprise at this unexpected flooding pattern.
Rather it was a belated realisation of the complete failure of successive local & state governments to give serious consideration to the level of risk associated with the extent and height of largescale land filling, which was now altering how both flood waters and stormwater (unable to be cleared by a drainage system design made inadequate by continuing urban growth) travelled across land within the town precincts. As well as the fact that this change in flood pattern meant more people became cut off from the town's risible evacuation plan & route.
Like the issues with the Northern Rivers flood watch system, the issue of Yamba's changed flood pattern remains unaddressed to date.
