|
The road into Yamba, Clarence Valley NSW, 4 March 2022 Credit: Clarence Valley Council via Storyful in Yahoo!
|
To
put it frankly Yamba township’s flood resilience is a
shambles.
Surrounded on all compass points by river, lake or ocean, much
of the urban footprint of the town is built on degraded sand hills
and reclaimed marshland or swamp across 16.92 sq km of coastal
land.
The
natural fingers of the Clarence River estuary
which intrude into residential streets are now exacerbated by a
fringe of canal estates which bring tidal riverwater right up
to the artificial soft shore boundary edges of the backyards, side
yards or front yards of so many homes and make it possible for
riverine flooding to enter more streets than it once did.
Ocean
storm surges occurring during destructive East Coast Low storm
events are something that are considered almost in passing when it
comes to resilience planning and flood risk management. Even
though authorities
are aware that days of heavy rainfall leading to soil
saturation accompanied by strong seas result in est. 1 in 1,000 chance that land
slippage will affect sections of Yamba Hill & environs public and private
property – including
residential dwellings. Such an event can coincide with
riverine and stormwater flooding in wider Yamba.
The
Lower Clarence River floodplain spans 500km2.
That is a substantial floodplain and climate change modelling
in BMT
Lower Clarence Flood Model Update 2013 indicates that all
along the lower river peak flood levels are expected to increase
in 1% AEP events.
The
natural protection of Yamba’s 690ha natural flood
storage area has over time been eaten away by
extensive landfill earthworks being created in preparation for
housing another 2,000-2,500 people in West Yamba. While completed
large scale earthworks elsewhere in Yamba are contributing to
increased stormwater flooding adding to the volume of flood water
flowing in from the Clarence River and into internal waterways and
floodways of a town whose current
population is 6,388 men women and children living in a
density of 377.6 persons per sq km.
Coping
with the town’s street plan and road surface heights which
lead to predictable internal road closures during major flooding. These closures will inevitably
occur ahead of any official advice to immediately evacuate during a
Lower Clarence River flood. Currently it appears such emergency
advice is not planned to be given until flood height
reaches 2.1m at Maclean – at which point Yamba’s only evacuation
route is highly likely to be closed in both directions.
In
2022 any evacuation by vehicle ahead of a flood front
was calculated to take a minimum of one hour for the journey
to Maclean via Yamba Road and the Pacific Highway to be completed. A
journey that in good conditions might take twenty minutes. [C.
Landers, Clarence Valley Council correspondence, dated 30 June 2022]
When
it comes to Yamba residents and visitors; state & local government along with emergence
services have placed the primary emphasis on “self-help"
when coping with rising floodwaters
or a need to evacuate, due to limited SES resources being spread
across the valley.
Added
to this is the fact that Yamba's flood heights expected ahead of active flood fronts and actual flood front heights as they reach the town are broad estimations. Because the
town has to rely on the Maclean flood gauge further inland due
to the strong tidal movement at the river mouth which is said to
distort any flood calculations derived from the Yamba
tidal gauge situated in the vicinity of the start of the southern breakwater wall.
Yamba
is an accident waiting to happen
and, it
does not inspire confidence,
when reading between the lines of the following newspaper article
it seems that Clarence
Valley Council administration is reluctant to obtain a written record of the lived
experience of
the wider population in Yamba over
the last three decades. Something that would complement the data
contained
in the anticipated report
by
BMT
WBM Pty Ltd.
Clarence
Valley Independent,
17
May 2023:
The
Yamba Community Action Network Yamba CAN Inc is urging Clarence
Valley Council to conduct a flood survey of all residents on the
Yamba floodplain so it can be incorporated in the updated Clarence
River Flood Study and Flood Model which are currently being prepared.
Consideration
of the impacts of the devastating floods in February and March 2022
will be factored into council’s new Flood Study and Flood Model,
and Yamba CAN Inc believes the studies would be better informed if a
survey was done to understand the impacts on individual residences.
When
Yamba CAN recently discovered a flood study being conducted by Coffs
Harbour City Council of residents in the Moonee Creek catchment area,
members questioned why CVC couldn’t do the same.
Flooding
impacts areas of Yamba differently, so to get a comprehensive picture
of how the entire Yamba floodplain is affected, Yamba CAN Inc
suggests CVC adopt a similar model to Coffs Harbour City Council, by
asking each household to describe how they were impacted.
Questions
in the Moonee Creek flood survey include: how long have you lived in
the region; have you experienced flooding within the Moonee Creek
catchment; have you experienced any other flooding event; please
provide a short description of any flooding you have experienced;
whether your home/business, garage, yard was flooded; were you able
to drive your vehicle to safety; what areas of the community are most
at risk of flooding; have you noticed any changes in the frequency or
severity of flooding in your area and to provide photos and depths of
the flooding.
From
answers to these questions, Yamba CAN Inc asserts CVC could develop a
comprehensive flood model of how individual residences are impacted
in times of flood.
The
important information obtained from the survey would assist with any
upgrading of west Yamba’s stormwater drainage system.
Yamba
CAN Inc sent a letter to CVC General Manager Laura Black, and all
Clarence Valley Councillors calling for a flood survey of residents
living on the Yamba floodplain to be included in the updated Flood
Study and Flood Model.
“It
has come to Yamba CAN Inc’s attention of another flood study being
undertaken by Coffs Harbour City Council in the Moonee Creek
Catchment area,” the letter states.
“This
flood study includes gathering information from all residents in the
Catchment area by means of a survey.
“A
similar survey of residents living on the Yamba floodplain is of
paramount importance to be included in the current Flood Study and
Model, particularly not only in relation to riverine flooding but
stormwater flooding during February/March 2022 which occurred two
days prior to the Clarence River flood crest reaching Yamba.
“Yamba
CAN Inc requests CVC undertake such a survey and the results be
considered in the formulation of the current Flood Study and Model.”
A
Clarence Valley Council spokesperson said council engaged BMT to
undertake flood modelling using the latest available property and
event data for the local government area to inform Floodplain Risk
Management Plans.
“The
plan will be presented to the Council for exhibition, providing
opportunity for the community to comment and provide feedback,” the
spokesperson said.
The
spokesperson said council doesn’t plan to do a survey of impacted
residents in Yamba.
“Council
does not intend to survey individual households in relation to this
matter,” the spokesperson said.
“However,
we will be undertaking a Yamba Urban Drainage Survey to capture
residents experiences in recent events, as we are currently doing for
Iluka.”