“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.
