South Dunedin and sea level rise

Written By: - Date published: 7:00 am, April 6th, 2017 - 44 comments
Categories: climate change, Environment, science - Tags: , , ,

In a week that brought more serious flooding to the North Island, Stuff reports that the University of Otago, the Dunedin City Council, and the Otago Regional Council have compiled a database of areas in Dunedin at risk from sea level rise.

Areas in South Dunedin less than 1 metre above sea level

Dunedin City

 

Dunedin has more houses under the 50cm above sea level mark than any other city in NZ. The new database looks at places less than 1 metre above sea level and includes flood hazards, how water might pond in different scenarios, house ages, demographic details, social assets and history. The University of Otago’s Centre for Sustainability has made a simplified version of the interactive map for the public that can show the different data.

South Dunedin by median personal income

 

From the University,

Dr Stephenson says asking how much sea-level may rise and how soon is important.

“But it shouldn’t overshadow the human side of the question, which is, ‘who may be affected and how should we respond?’.”

Dunedin City Council’s Second Generation District Plan proposal is for all new buildings in South Dunedin and other coastal areas to be relocatable. Developers are objecting of course, and it may be limited to residential buildings under 9m. It seems like a no brainer to me but I’m guessing most of the objection is because of the impact on the potentially lucrative development of the Otago Harbour waterfront.

It’s not just sea level rise. Dunedin is at risk from large rainfall events and these are expected to increase in frequency and intensity. Given the number of floods that the North Island has seen in the past month, now might be a good idea for similar mapping and database creation to be happening across the country (if anyone knows of other mapping, please link below).

Dunedin City Council commissioned a Peak Oil Vulnerability Assessment in 2010. It looks like Dunedin might be leading the way for NZ on preparing for the world we now live in and I’m guessing that South Dunedin residents in particular are having to grapple with the initial direct-impact realities of CC more than most in NZ. It’s harder to avoid seeing the climate for the weather when bylaws are about to affect your home and it’s not even raining. This isn’t flood prevention or even mitigation, it’s first steps in permanent change to how society functions. There is so much that needs to be done on auditing infrastructure and incorporating climate change into town and country planning. This is a start at least.

It’s also critical that we don’t think only in terms of adaptation, that we keep centred on mitigating the worst effects of CC and build that into everything we do. The Greens have a Bill that would require all government legislation to be considered within a Climate Impact Disclosure Statement and how the legislation would impact on climate and our GHG emission responsibilities. This would keep MPs and the public informed, give opposition parties more information to hold government to account, and would ensure that climate is a key consideration in the running of the country. Local bodies need to be stepping up for this too, so that it becomes normal for climate change to be at the front of our minds and how we manage our collective resources and communities.

Niwa’s Climate Change and Urban Impacts Toolbox

MfE’s Climate change effects and impacts assessment: A guidance manual for local government in New Zealand

Sea level rise map of NZ

The Green Party’s Legislation (Climate Impacts Disclosure Statement) Amendment Bill (draft for consultation)

Moderator note: climate change denial is not welcome here and will be moderated accordingly. I’m also aware that we could have big debate about whether 1m is a useful setting for councils and other bodies to work with. Please try and relate that back to the post, and let’s try and do something useful other than just talk about what is wrong.  

44 comments on “South Dunedin and sea level rise”

  1. Antoine 1

    I’m not sure how useful the 1 masl line is as an indicator. There may be homes above that line that are still highly vulnerable to storm damage.

    • dv 1.1

      Heres your chance then. WHAT do you suggest?

      • Antoine 1.1.1

        My suggestion is to get someone (meterologist, hydrologist?) To do a storm surge vulnerability zone and front foot that – rather than emphasizing the 1m line in the comms.

        • One Anonymous Bloke 1.1.1.1

          Antoine suggests we commission a study and do nothing in the meantime.

          At district and regional level, we have no choice but to plan for climate change because we see the effects directly: it’s far easier to open a conversation about “managed retreat” (for example) in a community that has first-hand experience of frequent floods.

          At a national level this government is in the way and needs to be knocked down and used as a sandbag, or something.

        • dv 1.1.1.2

          Knowing where the dangers areas are is certainly a step in the right dirrection. Other analysis can follow.

  2. BM 2

    Not looking good for South Dunedin.

    I can imagine the property owners will be rather pissed as this sort of prediction knocks a fair chunk off the value of their property and will probably turn south Dunedin into a run down slum.

    The issue now becomes can south Dunedin be saved? or is it worth being saved?

    • Paul Campbell 2.1

      South Dunedin is one of the densest areas of housing in NZ, while it’s not ‘a slum’ it’s largely not a high-income area, it’s lots of tiny houses with no backyards, lots of rental properties and pensioner flats, has been this way for generations

      • BM 2.1.1

        Would you build or invest in South Dunedin?
        How would you even raise finance or get insurance?

        I assume the council does actually have a plan to deal with this?

        • Paul Campbell 2.1.1.1

          Nope, I live on the hill, on purpose. My brother rents there, the water table is stupidly high.

          The council doesn’t really have a plan, though they at least mostly admit it’s an issue. Deciding that all new housing should be moveable seems to be a smart start

          • Draco T Bastard 2.1.1.1.1

            Getting to the point that they need to say that all new housing needs to have adequate floatation.

            And, yeah, if I was to buy a house I’d be looking at how high it and the surrounding land is above sea level.

    • jaymam 2.2

      Have a look at the 1 metre prediction for Auckland. Much of the CBD and seaside suburbs are below the 1 metre level. Anyway, what datum are they talking about? Mean Sea Level? Mean High Water Springs? Highest Astronomical Tide?
      I assume it’s MHWS.

      • lprent 2.2.1

        As someone who got exposed to earth sciences at a young age, I looked around New Zealand for a reasonably safe location to live. It turns out there isn’t one.

        So I did the next best thing, I brought a apartment in low block based on some impressive foundations. It is 85m above sealevel, just below the brow of a ridge on reasonably stable geology facing down into a gully with a higher facing ridge and with quite limited line of sight.

        It just happens to be inside the basaltic volcano field known as Auckland City, a type of volcano that usually telegraphs its intentions well in advance. But even so the geography should alleviate any urgent issues with the heavy (and short range) basaltic ash or volcanic bombs. And unlike most of NZ, Auckland is well off the major fault lines, and therefore doesn’t seem to have too many major earthquakes.

        Hey – I’m not paranoid. But after you look at the probabilities of natural disasters for a while and the potential downstream effects on peoples lives, you do get a wee bit cautious.

  3. dv 3

    I think that global insurance companies will have a role.
    Insurance premiums are going to increase in CC affected areas, if some properties will be insured at all.

    Maybe the insurance companies could/will build a factor into the premiums that reflects the countries response to CC gases?

    • Draco T Bastard 3.1

      The insurance companies have been aware of climate change and the increased risks for quite some time now. I find it interesting that our present government and climate change deniers the world over are ignoring what the insurance industry is saying despite them also telling us that business is always right – or, perhaps, it’s only the favoured businesses that are always right.

      Climate change threatens ability of insurers to manage risk

      The ability of the global insurance industry to manage society’s risks is being threatened by climate change, according to a new report.

      The report finds that more frequent extreme weather events are driving up uninsured losses and making some assets uninsurable.

      How the Insurance Industry Is Dealing With Climate Change

      “Our business depends on us being neutral. We simply try to make the best possible assessment of risk today, with no vested interest,” says Robert Muir-Wood, the chief scientist of Risk Management Solutions (RMS), a company that creates software models to allow insurance companies to calculate risk. “In the past, when making these assessments, we looked to history. But in fact, we’ve now realized that that’s no longer a safe assumption—we can see, with certain phenomena in certain parts of the world, that the activity today is not simply the average of history.”

      • dukeofurl 3.1.1

        EQC is the only place you can buy ‘flood insurance’

        You wont find it in any of the standard company policies
        eg State
        “This is the cover provided by the Earthquake Commission in the event of damage to houses and their contents caused by natural disaster such as a flood or earthquake.”

        But their cover is conditional
        http://www.eqc.govt.nz/what-we-do/house/conditional-building-consents

        Flooding would certainly be a ‘hazard’ for any new buildings in the area

  4. dukeofurl 4

    Its seems that South Dunedin has the affects of 3 things combining.
    1)It sits on an old swamp which usually means the ground level is sinking to some extent
    2)The shape of Dunedin harbour which can lead in times of low atmospheric pressure combined with winds in the right direction can lead to the sea level at high tide being ‘pushed up’ at the end of the harbour.
    3) the general rise in average sea levels

    I dont know if this is an complwete answer for South Dunedin but I noticed in Cairns which has most of the older city suburbs on reclaimed swamp land in an area of very high seasonal rainfall. These suburbs are crisscrossed with large drainage ‘canals’- they are roughly the width of a normal road and allow rainfall from the hills surrounding the flat land to reach the estuary of the Trinity river. ( The low lying areas get higher areas rainfall as water will flow to lowest point, maybe a bypass canal to the ocean frontage)

    • Paul Campbell 4.1

      A friend points out that a canal between the harbour basin and St Kilda could produce good tidal power generation …. build a canal down Queens Drive (we really don’t need two) which used to be train tracks anyway

      • dukeofurl 4.1.1

        Tidal power is best done at the opening to a inlet not at the far end.
        That would put the best location between Port Chalmers and Quarantine Is and Quarantine Pt. this location has 3 narrow openings.

        • Paul Campbell 4.1.1.1

          My plan for saving Dunedin involves putting a dike across there, and another across the St Kilda/St Clair beach ….

  5. Paul Campbell 5

    Before everyone goes crazy about South Dunedin, it’s not the lowest spot in Dunedin, the area around the airport is – the Taieri river is tidal around there but there are already dikes protecting the airport (mostly) from flooding.

    The thing I don’t understand: the regional council is responsible for things like protecting people around the rivers from flooding – what’s the difference between that tidal portion of the Taieri and St Clair beach? in that the Regional council is responsible for one but not the other (of right, of course, farmers)

    • weka 5.1

      At a guess I’d say that it’s because the ORC is responsible for rivers not oceans. It’s the Taeiri River that involves them in that. Am just guessing though, I don’t know about the airport issue.

      We can get crazy about the airport too, but my first comment is that there is no alternative to avgas on the horizon and in cc terms we will just have to stop flying except for critical reasons. I’d want to see adaptation conversations re the Dunedin airport happen in that context.

      I’d also like to see agriculture potential of the Taieri Plains discusses in terms of producing food for Dunedin.

      • Paul Campbell 5.1.1

        to do that you’ll have to stop Mosgiel expanding over what is some of the best soil in the entire country.

        (see above, I think we should put up dikes and reclaim the upper harbour, we could even put the airport there …. and reserve that wonderful Mosgiel soil for what it does best)

  6. Sabine 6

    i have been saying the same thing now for a long time,

    when insurance companies stop insuring businesses and properties then we will start talking about the issue of raising water levels and other inconvenient truth. Until then, many will just expect someone else to do something.

    btw, Edgecumbe is evacuating as ‘wall of water’ hits town.

    • weka 6.1

      Lots of business in South Dunedin, I’m guessing we’ll be hearing from them in due course.

      • Sabine 6.1.1

        i am not diminishing the issues that Dunedin has.

        What i am pointing out is that these issues are shared, and sadly until Insurance Companies balk at bailing out properties and businesses and stop insuring these that are in high risk areas nothing will happen.

        I looked two years ago at the property in New Lynn that was flooded in the last floods. On the way by there three days ago, i was shocked at the damage done, one side of the roads about 20 businesses all gone, and the ‘my’ shop on the other side has two walls gone, and the three businesses and one large upstairs businesses are are all gone too.

        This is one and the same boat Weka, Dunedin at one end, Akl at the other end, and Edgecumbe, Whanganui and other places in the middle. Non of them is prepared for what is coming.

        And in the meantime we build willy nilly, without a care in the world, concreting nature over, ripping out trees like there is no tomorrow and we wonder why shit is not working for us anymore.

        So it does not matter how many businesses or houses will be lost, until the Insurance companies stop paying out nothing will happen.

        • weka 6.1.1.1

          I wasn’t suggesting you were diminishing Dunedin’s issues, I was actually agreeing with you and pointing to the fact that South Dunedin has a lot of businesses in it. I’m guessing they’re starting to feel nervous too.

          I do think that Dunedin is a bit ahead of the ball compared to the rest of the country. It’s now framing this in terms of CC. The rest of the country is still largely talking about weather.

          Re the insurance, I agree there will be a big jump in attention once they start playing hardball. I think there is smaller change happening in the meantime. And the DCC banning the build of non-relocatable houses in South Dunedin (and beside the harbour) isn’t ‘nothing’. It starts the difficult process of what do to about SD, but just as important, it wakes people up. Even a few years ago people weren’t willing to take this seriously, now they are.

          edited.

          • Sabine 6.1.1.1.1

            yeah, my wording could have been better.

            I am watching the crumbling hillsides in AKL with interest. There is one overbuild cliff just right above the motorway leading to the Harbour Bridge. 🙂

            Can you imagine the mess when that pile of sand decides to slide?

            Te Atatu Peninsula with its multi million GJ Garnder Piles right at the water front, while the new motorway was build above sea level.

            Its there, everyone can see it, most know it, but still non so blind as those that keep their eyes closed on purpose.

            • weka 6.1.1.1.1.1

              I don’t know the area, can you find a picture?

              I’m old enough to remember Abbortsford (big slip in Dunedin in 1979). It beggars belief that we are still building in dodgy places.

              From what I remember some big chunks of east Chch were deemed unsuitable to build on because of the instability of the ground and the council and developers went ahead anyway. And that assessment of the ground wasn’t that long ago.

              It’s end of the empire stuff. If we have the money and big enough machinery why not keep building bigger and better? 😉 Boys with their toys, and the colonial mindset, everything has to be improved regardless.

              The interesting thing about Sth Dunedin is that it’s low socio economic and has lots of elderly people living in it. I’m hoping this will force us to some collective action.

              • Skeptic

                You must have seen the same maps and reports I saw back in the late 1970s that were with the old SAC (State Advances Corporation) and the old CWB (Chch Water Board). The offending developers were Enterprise Homes and Maugers – but they’re no longer around to answer for Bromley & Bexley. I would hazard a guess that deep in the bowels of DCC records there are similar files with reports and maps showing where building was initially prohibited due to unsafe/low-lying ground. Who paid off whom to get the houses built?

                • weka

                  I didn’t realise it went back that far. I only knew because after Chch2 some geologists spoke out about it.

                  South Dunedin suburbs are much older and I think the commitment into developing there would have been made long before there was recognition of a problem, or that level of corruption/stupid.

                • weka

                  Found this tonight, about the Invercargill 100 year flood,

                  The January 1984 floods also changed views on what constituted a 100-year flood, he recalled.

                  For Mr Goodman and his team, the floods were a vindication in one sense. They were about to be taken to the then equivalent of the Environment Court for making things difficult for a developer planning a subdivision on low-lying land.

                  After the floods, the hearing never occurred. But to this day Mr Goodman holds fast to a belief for public education about the lie of the land and what is likely to happen if there’s a flood.

                  http://www.stuff.co.nz/southland-times/news/features/1984-floods/808687/If-its-this-bad-now-whats-still-to-come

                  • Skeptic

                    In the late 1970s the HCNZ – before it was downsized – was charged with “design & build” and had a whole section devoted to just that in each of the main branches in NZ.

                    Among the files – there were dozens of them – were geological surveys of nearly all NZ cities, major and minor along with water table reports, soil reports, erosion reports, probable liquifaction reports etc. In Chch, the Chch Water Board had files and maps showing the 1860 flood expanse, projected failure of Halkett stop-banks flood damage etc. I saw these, and so did innumerable other who worked there. Prior to Bexley and Bromley being built and a lot of the development near the Avon loop and east of the Avon , south of Aranui and Wainoni, much of the area was designated “Unsuitable for Building” in very large red capital letters.

                    I’m sure Dunedin had/had similar files and maps.

                    How these areas got built on/developed is something I guess must be too scandalous to make any type of inquiry about, because it would involve disclosure of bribes and corruption that far too many Nats and supporters would care to kknow about.

            • dukeofurl 6.1.1.1.1.2

              ‘Te Atatu Peninsula with its multi million GJ Garnder Piles right at the water front”

              Auckland Council GIS maps show Te Atatu waterfront properties being 10-15m elevation, a few older areas may be less than that on the estuary side.

          • dukeofurl 6.1.1.1.2

            ‘Non relocateabale’ just means no concrete slab floor, brick walls and tile roof.

            • weka 6.1.1.1.2.1

              I’m guessing the issue is people that want to build multi story and do out of the ordinary architecture.

  7. Philj 7

    Linda Clark expressed very serious concerns about the climate change issue on Jim Mora THE PANEL. It’s a classic, the gold is about 20 minutes in when Linda delivers the missile. Very funny and Jim is brilliant and so funny haha. A must listen. Brave stuff Linda. “The Panel with Gary McCormick and Linda Clark (Part 2)” on Radio New Zealand

    http://www.radionz.co.nz/national/programmes/thepanel/audio/201839285/the-panel-with-gary-mccormick-and-linda-clark-part-2

  8. Sabine 8

    i am not sharing your optimism, but i blame my inner german for that.

    This is an article from England last year, and i expect the same to happen here with regards to insurance.

    http://www.dailymail.co.uk/news/article-3382241/First-flooded-fleeced-Victims-forced-pay-thousands-despite-promised-180million-Government-insurance-three-years-ago.html

    I have a hard time believing that anything worthwhile will be done to a poor/low socio economic area. They rather displace the people elsewhere then to finally start addressing the issue. And sadly, the Council alone can’t do it, it needs resources from the government and for now i don’t think it will happen.

    To an extend it abandonment might even needs to happen, but will it be done humanly or will people just be expected to ship out to where ever.

    https://www.google.co.nz/maps/search/Flanshaw+street/@-36.8414136,174.7452135,329a,35y,270h/data=!3m1!1e3

    Ring Street TCE. lol.

    • dukeofurl 8.1

      “i expect the same to happen here with regards to insurance.”

      Ah no. EQC is really the only place where you can get flood insurance for this type of thing. ( but you have to have fire insurance )
      http://www.eqc.govt.nz/what-we-do/eqc-insurance

      • Sabine 8.1.1

        these were areas that previously did not flood. So getting flood insurance was no issue, now however some of these places get regularly flooded and hence no insurance anymore or only with a huge deductible.

        this will happen here too.

        and i think the EQC is having problems already

        http://www.interest.co.nz/insurance/85658/iag-and-tower-demand-eqc-coughs-cash-having-allegedly-short-changed-thousands

        • dukeofurl 8.1.1.1

          I have to repeat this, but you havent read it properly. You dont buy flood insurance as a standalone. Its part of the EQC cover, I would pay the same rate as those along the Whanganui or indeed South Dunedin, and there is no chance of me flooding.

          Yes dealing with EQC would be one of lifes horrors, but the article refers to ‘land damage’ ( liquefaction in this instance) which is different to flood damage.

          • Sabine 8.1.1.1.1

            i am not talking about flood cover per se….

            what happens to the stuff inside your house? Home and contents? How many time do you think you can claim flood damage before they balk at insuring such things near a flood prone are?
            Car Insurance? Flood Damage?

            is that all coverred by EQC and how long can EQC pay out if these floods, earthquakes and wild fires become standard?

            that is what i speak about when i say “Insurance” .

  9. timeforacupoftea 9

    These guys are crazy from The University of Otago’s Centre for Sustainability always negative with no solutions only retreat retreat retreat, but then you expect that from an academic don’t you.

    It was far worse in the 1950’s 1960’s, our back yard in Tainui would go under water 5 times a year, but the water receeded very quickly.
    Around the late 1960’s the council built a pumping station and our back yard would only flood once or twice a year.
    We could dig down 2 spade depths in the winter and water would come and go daily, maybe it was tidal I never new why.
    Old photos of Tainui showed most of the area as a sort of inlet.
    Where Tahuna Intermediate School is, in the 1950’s that was a large pond where in winter it would freeze over and I could walk across it and play etc. It would stay frozen for a couple of weeks. Winters were much colder then at least at night but beautiful clear days.
    If the sea is ever to rise we do have many options, here are two ideas.

    1) A dam could be built between St Martins Island and Portobello.
    A lock could be built between St Martins Island and the mainland near Port Chalmers and ships could be allowed up into the upper harbour when there was no chance of flooding in South Dunedin. But most of the time the upper harbour could be kept at half tide or whatever height tide was necessary to keep South Dunedin dry.
    Which means there is this huge area for drainage during heavy rain etc.
    Some parts of the Upper Harbour could be filled in for future housing.

    2) Part of the upper harbour could be filled in obviously higher than the Portobello Road and block by block of South Dunedin could be shifted there temporarily so each block of South Dunedin could be raised to the required height above predicted sea level, then the houses could be shifted back.
    You might ask where would we get the fill from. Well there are many hills around Dunedin so no worry there.

  10. Michael 10

    There used to be a lot of Labour voters in Dunedin South before Clare Curran became the MP. Perhaps that explains why so little political will exists towards the people who live there?

  11. red-blooded 11

    “…before Claire Curran became the MP”

    Hey, Michael, Curran was reelected and her personal vote was higher than Labour’s party vote (which was still considerably higher than the national average). How does your dismissive comment account for these inconvenient facts?

Recent Comments

Recent Posts

  • New digital service to make business easy
    A new digital platform aims to make it easier for small businesses to access services from multiple government agencies, leaving them more time to focus on their own priorities. Prime Minister Jacinda Ardern and Minister for Small Business Stuart Nash ...
    4 days ago
  • Million-dollar start to gun collection events
    Million-dollar start to gun collection events  Police Minister Stuart Nash says a solid start has been made to the gun buyback and amnesty after the first weekend of community collection events. “Gun owners will walk away with more than ...
    5 days ago
  • Praise after first firearms collection event
    Police Minister Stuart Nash has praised Police and gun owners after the first firearms collection event saw a busy turnout at Riccarton Racecourse in Christchurch. “Police officers and staff have put a tremendous effort into planning and logistics for the ...
    5 days ago
  • New Police constables deployed to regions
    Seventy-eight new Police constables are heading out to the regions following today’s graduation of a new recruit wing from the Royal New Zealand Police College. Police Minister Stuart Nash says the record high number of new Police officers being recruited, ...
    2 weeks ago