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Much worse, and sooner

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Photo: Marten Rabarts

by Kerry Wood
Wellington’s weather has been wild recently, and we need to be aware of the consequences: much worse, too soon. A recent NIWA press release quotes Dr Scott Stephens, NIWA’s Chief Scientist for Coasts and Estuaries:

Rising seas are slowly causing a trifecta of impacts along coastlines in Aotearoa: increasingly frequent flooding, coastal erosion and even permanent inundation …

Our research shows that it’s the first of these three impacts – increasing flood risk – that’s likely to be the main driver of adaptation efforts by coastal communities, and this tipping point is likely to be reached within two to three decades – sooner than many of us expect …

Frequent flooding is undesirable for communities. Adaptation actions include things like building new seawalls or other protections to mitigate coastal flooding, but these may not be the best long-term solution…

Regional Council studies give a likely sea level rise of 0.2m to 1.4m by 2100, with an extreme value of 2.4m. Wellington needs to plan for two metres or more.

Recent problems are mainly along Wellington’s south coast, but the risk areas are much wider: Lower Hutt to Alicetown, central Wellington from Kaiwharawhara to Kent Terrace, and inland to Thorndon Quay and the Golden Mile, Kilbirnie from Cobham Drive to Coutts St, and much of Miramar and Seatoun. Worse still storm-surge and wave height will add to sea level rise.

As Dr Stephens puts it, all this is undesirable, but sea walls or other protections may not be the best long-term solutions. In other words, consider retreating.

Alternatives to retreating include sea-walls; raising ground-levels, with buildings either raised or their entrances moved to first-floor level; draining water into underground tanks, for pumping out later; and perhaps other options. None of them are very attractive, and it seems certain that retreating will be the best option in some places.

A likely example would be rebuilding Wellington’s south coast roads at a higher level, probably as bridges where large waves are expected, and abandoning everything at a lower level.

What is done where, and who pays for what, are going to be very tough questions.

6 comments:

  1. HT, 14. October 2021, 15:21

    And we’re developing Shelly Bay because? We will be up for millions in the next few years to save the area and retain the road. The developer will be long gone.

     
  2. Ray Chung, 15. October 2021, 14:40

    HT: You took the words right out of my mouth! As I read this article, this is exactly what I thought! The WCC should rescind any permission to build there unless the developer undertakes to pay for all costs to rebuild the road and take full responsibility for any damage to the building.

     
  3. HT, 15. October 2021, 16:31

    Ray Chung the facts don’t seem to matter. WCC continues on with Shelly Bay regardless. I guess it takes courage to admit you’ve made a mistake and fix it.

     
  4. Amacf, 15. October 2021, 16:36

    For ease of administration, if nothing else, WCC should rescind any permission to build within the tsunami zone and take those areas out of its revised district plan with a view to eventual clearance. We can’t be too careful, can we?

     
  5. bsmith, 19. October 2021, 8:59

    Do you people really think that sea rise will be anywhere near these levels ?

     
  6. Peter Steven, 19. October 2021, 10:44

    Bsmith. Yes, I’m not a climate scientist but I trust the research of the experts.

     

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