Welcome to the Midnight Collective Broadsheet 122
Actively
supporting NZ’s endangered wetland birds
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| Flooding on the Western side of the expressway |
The
Wharemauku can rise in a flood very quickly, but it also falls quickly. So this
flood was unusual in that it stayed at bank topping level from Friday night
through Sunday. Yet unlike last year’s major flood, the creek never breached its banks to flood our local housing.
There was flooding down at the beach, but the Wharemauku stabilised at around
two thirds of a metre (two feet) below the level where residential houses are
at risk. These photo’s tell the story.
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| Wharemauku downstream at the height of flood |
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| Pollution monitor on western side of expressway. Water level 2 feet+ below last year's flood |
During
the big flood the photographer would have been standing waist deep in water
taking these shots and the flood had risen well above the monitor.
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| Usual flood plain of Wharemauku East of Expressway - unaffected at height of flood |
Upstream
on the eastern side of the expressway the creek was contained within its stop
banks. This drain (pictured) is the point at which the creek usually begins to overflow
into the paddocks beyond, helping to relieve flooding downstream. As you can
see it is still well below the levels where that backfilling occurs.
So this flood would not
normally have resulted in a major inundation of this area yet it did. Why?
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| Flooding on Eastern side - expressway to right |
The
cause can be traced to the new drain set below the expressway bridge that now
drains our dune lake into the Wharemauku.
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| New drain inundating dunelake on Western side of expressway |
The flood pushed aside the steel
sheet blocking the drain. The NZTA removed this sheet on the Sunday morning in
an effort to drain the area but the flood didn’t begin to recede until later
Sunday night. This backfilling filled both sides of the expressway and very
quickly. An area that had been pumped dry on the Friday night was completely
inundated on Saturday morning while the drain previously used to pump polluted water into Drain 7 was also overwhelmed.
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| Drain at back of dunelake showing new work to clean it up |
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| Same area a day later -western side -expressway in distance |
The
implications of this are important because the NZTA have moved the
Wharemauku’s flood plain, over to the other side of the creek, much closer to
housing while back filling feeder drains coming through the town centre. This area will now flood at much lower levels than previously and there is no indication from official sources –the District and
Regional Councils, let alone the NZTA itself, that they are aware of these
developments, or how concerning they are.
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| New plantings inundated on the western side of the expressway, |
As
you can see from these photographs this is a very serious flood of this area.
It has never happened before in the five years we have been monitoring this
dunelake and it appears to have taken all the relevant authorities by
surprise. Do they even know, because there has been no publicity about
it. At the time we were monitoring
this, through the Saturday and Sunday, the only staff we encountered were the
lone worker with the shovel, and the digger driver who removed the steel
sheet.
It
is still not clear exactly why this area flooded both sides of the expressway
so quickly, and this is a worry bearing in mind that this flood would not normally have caused problematic flooding. The NZTA however, must have been aware that this
backfilling would occur but we have no confidence that they knew the extent
to which it would take over the area, nor the wider implications.
In the longer term the
NZTA have managed to turn a unique urban dunelake into a flood plain that has
already destroyed much of their recent plantings. It will gradually change the character of this area as it picks up silt from regular flooding. What will be the longer
term implications of this? Will it work to undermine the earthworks of the
expressway, which are primarily comprised of sand?
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| After the flood - the drained dunelake now devoid of wildlife. |
As a final note it is worth recording once again, that the NZTA stated to the
Board of Inquiry that they would take only .18 hectare of this wetland and
leave the rest untouched. It has now drained the area completely and emptied its rich
bounty of wild life.
Track
we were listening to while posting this the Rolling Stones Start Me Up. OK well, they may be way past there glory days, and Jagger lost all cred. when he buttered up to Thatcher; but Keith Richard well, he remains the heart and soul of it all.
You can start me up
You can start me up I'll
never stop
I've been running hot
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