*https://tinyurl.com/yygudhnh - Dunedin's extreme waterfront makeover gets $20m boost
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Homes of 240,000 Kiwis in way of worst case 2100 sea level rise, study indicates
....Climate Central has an interactive world map, including New Zealand, which enables users to play around with a range of scenarios to get indications of which parts of New Zealand will be affected by rising sea levels this century......
https://www.stuff.co.nz/environment/climate-news/117013714/homes-of-240000-kiwis-in-way-of-worst-case-2100-sea-level-rise-study-indicates
Flood-prone South Dunedin's future depends on science not propaganda
The
future of low-lying South Dunedin is in the hands of science, not those
who misinterpret or politicise its flooding problems.
That was the warning from Dunedin-based GNS Science geologist Dr Simon Cox at a large gathering of scientists in Christchurch.
Often when South Dunedin flooded, it was held up as the exemplar of
what climate change induced sea-level rise might look like in New
Zealand.
However, there were other factors behind the suburb's vulnerability to
flooding that were being ignored, including run-off from Dunedin's
hills........
..........Results from Lidar surveying – in which light pulses are used to
measure land elevation – had been misinterpreted into South Dunedin maps
with "blue bits" showing where climate change flooding would supposedly
be worst, he said.
"If you look at the Lidar level and if you look at the Parliamentary
Commissioner for the Environment reports, they highlight South Dunedin
as being of concern because of the height of South Dunedin relative to
sea-level. And that is really useful from the perspective of
highlighting areas to do some work.
"But what then happens is people take the Lidar information and try to
get clever and they say, 'right, plus 1m [sea-level] and this is what it
will look like with 1m of sea-level rise'.
"And they couldn't be further wrong. They couldn't be further annoying
for the people who have got their house sitting under that blue bit.
"The reason it is really annoying is the current problems in South
Dunedin are where the run-off comes from the hills. It is a flooding
issue from surface run-off and it is not a groundwater-rise issue.
"When you do this sort of thing, you run the risk of basically getting
all this knee-jerk reaction from the society against that model, because
they haven't had wet feet yet. But it is starting to affect their
property values and they can't get insurance because the insurance
company actually believe it.
"So we have to dispel that myth around what happens when you force the theme of the sea-level rise."..........
Some Comments from the Stuff site:
326 days ago
Jantar
I
was at that conference, and this was an extremely informative
presentation.. The reasons why the water is not draining away is simply
that the infrastructure is old and designed for a much smaller
population density. The result is that water is running off from the
hill suburbs faster than the drainage system can cope. This is
particularly obvious now now that the hill suburbs are built up with
roads and other impervious structures putting more surface water onto
the low lying land and less storm water into the ground.
326 days ago
TooEasy
Schilhol
airport in Holland is more than 3m below sea level, built on a drained
lake bed (swamp) and is one of the busiest and most reliable airports in
the world.
One third of the Neatherlands is below sea level, 6.7m
at its lowest point and they are not retreating in the face of climate
change, they are adapting or fixing the issue.
The area of South Dunedin that gets flooded is next to the hills and it only happens after heavy rain.
We need more logic and less ideology
325 days ago
bigwhoop
The
issue isn't "what do we do about sea level rise". This WHOLE STORY is
about an expert pointing out that there are other problems to consider
as well.
327 days ago
A E Walsh
Built in a bad location. only going to get worse. Maybe time to relocate South Dunedin.
326 days ago
atrout
Explain
how that would work and the costs of relocating this community?
Seriously... try the exercise and understand the issues and dollars
involved.
327 days ago
ex LBP
"There
is no point trying to engineer anything if we don't know how much water
is coming out of the hills and flowing into the ground. How can it be
so hard to work this out? You know the rainfall in mm/hour, you know the
area so multiplication will tell you the volume of water, you need an
allowance for rainfall absorbed by the soil which will vary depending on
how wet the soil is etc, it should be easy enough to work out the
catchment areas for the streams/rivers which would allow them to
estimate the water flow at each stream/river according to rainfall.
327 days ago
Muscleguy
Depends
how blocked the pipes are, how good the records of the pipes are, how
leaky the pipes are and also how good the connections from the gutters
along the hill roads are to the drains. That is a lot of stuff to know
about and measure. Knowing the rain falling is only part of the
equation, Einstein.
I'm a Scientist and my father and both grandfathers were engineers. Build quick and wrong and repent at leisure.
Oh
yes, how absorbent are the hills? Soil type, vegetation (thirsty trees
are good), size of gardens and paving levels. Something else to know
because the hills will have a holding capacity for rain and that needs
to be known as well as the runoff is what falls MINUS the sponge
effect.
326 days ago
victual_13
Working
out catchment areas is the easy part. Figuring how the hill catchment
react is the tough bit. Subsurface storage, durface roughness,
antecedent conditions, bedrock fissures, rainfall pattern and on and
on.
327 days ago
Flaneuse
Sounds
sensible to me. At some time during the sequence of Canterbury quakes
(around 2013, I think) there was a huge rainfall, which badly affected
areas of the Port Hills - in particular Lyttelton and Sumner. Both of
these places were affected hugely by runoff from the hills that
overwhelmed the damaged and/or poorly maintained stormwater
infrastructure. Fixing that, and clearing culverts and other waterways
seemed to have helped enormously. Do all of that in South Dunedin first
then see what else needs to be done to mitigate the effects of sea level
rise.
327 days ago
waynewhoever .
My
Grandmother born 1881 and lived in South Dunedin,she used to tell of
flooding in the ditches at South Dunedin right up to Cargills Corner. I
lived in South Dunedin in the 1970's not that far from St Kilda
beach,when the tide came in the back section was very wet and when the
tide went out it dried out,dig a hole about 3/4 metre deep and it was
worse --- South Dunedin was known/referred to as "the swamp" years ago
and most likely still is by older folk -- Always a bit damp out there...
327 days ago
Muscleguy
With
a drainage system and two (iirc) pumping stations. I remember the
pumping station at Musselburgh was there when we moved there in '72 but
it looked pretty new then. That was the change. Do it like the Dutch.
327 days ago
wendy6
Flooding
is only flooding if it effects people, ever since man existed and more
so in recent centuries we love to build near the sea, in estuaries, old
flood plains and the bottom of valleys alongside babbling brooks.
Southshore in chch is a classic, shifting sands on one side, the estuary
on the other and very low lying, who would have thought that would
create any problems.
Then we cover vast areas with concrete
and install stormwater systems that carry water to those babbling
brooks in minutes rather than the days it use to take to get there.
Most
of the area surrounding chch on the plains is covered with old
watercourses/flood plains which one day in the event of monumental rains
may flow again.
Mankind has created most
flooding problems for themselves by building in some pretty dumb places
even if they are attractive. Very little of this has anything to do with
climate change.
327 days ago
inastew
This
isn't a new problem, I can testify that 50 years ago we had to wade
between buildings at St Clair School, later at Intermediate and High
School Tonga park could be flooded for more than a week on end. There
must be engineering solutions to fix this problem ( see The Netherlands
). Since the incorporation of St Kilda, Dunedin City and Ocean Beach
Domain into one council and the formation of Otago Regional Council
there is no excuse for the lack of action. But at least the University
is safe from flooding, thanks ORC.
327 days ago
Muscleguy
The
university up on the rocks and always has been. Why it has these modern
tower buildings, firm foundations. Why bring that into the discussion?
They didn't build it on lake Logan, that is still largely a park. Had
they done so your criticism might make sense.
326 days ago
inastew
Your
argument suggests they waisted their money but being built on erodible
river stone, and lot of it is on flood plain, something should be done.
But miliions spent on it for a 1 in 100 years risk, rather than 1 in 10
year actual event that could be partly mitigated ( read other comments
). Maybe the priority for the councils and comments here should be for
those that actually pay rates and live in South Dunedin.
327 days ago
mikenette
Congratulations
Simon Cox. Just as he did after the first Canterbury quake a realistic
assessment of the problem and likely future scenarios!
327 days ago
kmf
If
the land is only 0.5m above high tide, then it doesn't matter if the
rain is running off the hills or not, you will get flooding if the sea
level rises. Perhaps there are also issues with runoff not being
directed away from the area, and perhaps sea-level rise and rain run-off
can be handled by building swales and installing pumps, but these
engineering works will still have to take sea level rise into account.
For those owning land in low-lying areas, unless you can convince the
council to build these works (to the level that insurance companies are
happy), you will be owning a devaluing asset. If you can get council to
act, that will set a precedent too - so it won't be easy and will
involve a lot of red tape.
327 days ago
Muscleguy
There
are already pumps and there have been pumps for decades. There's a
height restriction on buildings because the soil won't support them and
the liquifaction risk in a quake (known about since the big San Fran
quake back end 19thC). You write as though you know nothing about Sth
Dunedin.
The Dutch maintain areas below sea level.
If your defences are high enough and you pump out the rain you can exist
below sea level.
327 days ago
Colin Fenwick
"So we have to dispel that myth around what happens when you force the theme of the sea-level rise."
Well said Dr Cox. It's a pleasure to see Stuff publish an article that pushes back against the 'consensus' that regularly
"misinterpret or politicise" the subject.
"misinterpret or politicise" the subject.
327 days ago
Ekrub
Typical
of government, be it local or national to get something wrong and then
run with it. A big concern indeed for South Dunedin, I hope they get it
sorted. Also I don't thinks its really fair that insurance companies
suddenly just decide to stop insuring a property due to increased risk,
isn't that what insurance is supposed to about, to protect you and your
stuff from potential risk.
327 days ago
kmf
Insurance
companies insure against risk, but charge accordingly. If the chance of
flooding is 1 in 100 years, then they will charge at least 1/100th the
likely cost of repairs each year. If it's 1 in 2 years they'll charge
half the cost each year, etc
So the cost of
flood insurance will go up and up until no-one can afford it. You will
still get fire and theft cover, etc, but flooding cover will be
prohibitive. And your property will flood more and more. As a result
land values will drop.
327 days ago
atrout
The
solution may not be in science, it is probably largely an engineering
situation. Some resource consents are now requiring solutions which
protect coastal areas to allow for a period of observation to determine
the longer term trends in sealevel change. That is a smart response,
using engineering to create meaningful observation periods to test the
science. An extra 500mm in height buys a lot of time at 1.2mm annual
rise. All giving time to plan over decades withou panic.
327 days ago
Say it
I think you're right, an insurance company does insure 'risk' however they don't as, they will say, insure certainites...
And insurance companies view some areas as bound to be exposed to some severe hazards at some stage, most commonly weather related ones.
Understandably then, their investors who back them, view the insuring of some areas as a bad investment as it holds a high risk of a payout.
Just like ensuring a teen driver with little experience, multiple traffic convictions and previous claims - why would you insure them to drive a powerful costly sports car?
And insurance companies view some areas as bound to be exposed to some severe hazards at some stage, most commonly weather related ones.
Understandably then, their investors who back them, view the insuring of some areas as a bad investment as it holds a high risk of a payout.
Just like ensuring a teen driver with little experience, multiple traffic convictions and previous claims - why would you insure them to drive a powerful costly sports car?
There is a lot of alarmism surrounding sea level rise so it worth noting what the eminent physicist and specialist in climate science reassuringly says about it.
ReplyDeleteRichard Lindzen
Sea level rise:
Globally averaged sea level appears to have been rising at the rate of about 6 inches a century for thousands of years. Until the advent of satellites, sea level was essentially measured with tide gauges which measure the sea level relative to the land level. Unfortunately, the land level is also changing, and as Emery and Aubrey note, tectonics are the major source of change at many locations. Beginning in 1979 we began to use satellites to measure actual sea level. The results were surprisingly close to the previous tide gauge estimates, but slightly higher, but one sees from Wunsch et al (DOI: 10.1175/2007JCLI1840.1) that one is in no position to argue that small differences from changing methodologies represents acceleration. Regardless, the changes are small compared to the claims that suggest disastrous changes. However, even in the early 1980’s advocates of warming alarm like Stephen Schneider argued that sea level would be an easily appreciated scare tactic. The fact that people like Al Gore and Susan Solomon (former head of the IPCC’s Scientific Assessment) have invested heavily in ocean front property supports the notion that the issue is propagandistic rather than scientific.
Here us an item from the GWPF quoting from a paper presented by Dr David Whitehouse that points up the uncertainties of ocean temperatures.
ReplyDeletePress Release 08/11/19
New Paper: Ocean Temperature Changes Are Uneven And Uncertain
click on the image above to watch the video
London, 8 November: A new paper from the Global Warming Policy Foundation looks at how scientists monitor changes in ocean temperature and finds a story of huge uncertainties and surprising findings.
For example, while warming might be expected to be fairly uniform, measurements suggest that it is regionalised, with parts of the South Pacific, in particular, warming more than elsewhere.
As the report’s author, Dr David Whitehouse, says, it is hard to draw firm conclusions about what is happening in the seas:
“The oceans can absorb far more heat than the atmosphere, so temperatures changes are extremely small and therefore hard to measure reliably.”
“The energy that would raise the temperature of the atmosphere by 4 degrees C would only raise the ocean temperature by a thousands of a degree, barely detectable.”
“Measuring changes in the ocean heat content are at the limits of our current capability and are made with significant uncertainties and unknowns.”
A recent claim that warming of the oceans was accelerating had to be withdrawn after errors were found in its uncertainty estimates by an independent scientist.
Dr Whitehouse is available for comment at david@davidwhitehouse.com
Cold Water? The Oceans and Climate Change can be downloaded here (pdf)