Flood problems on Taieri flood plain

The Taieri is a flood plain, with much of it barely above sea level, separated from the Pacific Ocean by a range of hills bisected by the lower Taieri Gorge.

Because it has been enriched by flood sediment for a long time it is fertile and therefore has been good for farming, when it isn’t waterlogged.

Because it is flat it has been popular for housing. Some of the biggest growth in the Dunedin area has been in Mosgiel and on other parts of the Taieri. It seems to have been easier to get consent to convert arable flat land into subdivisions than much more marginal land that is well above flood risk.

ODT: Flooded residents lash out

Taieri residents sick of their homes and properties being flooded are fed up with being ignored by local politicians.

Dunedin Mayor Dave Cull and other local government representatives at a flood recovery meeting in Coronation Hall last night acknowledged more could be done to protect residents in some areas and promised to try to address the list of issues raised.

However, solutions could come at a significant cost to the Dunedin City Council, Otago Regional Council and the city’s residents.

Earlier, residents of the flood-hit area pointed the finger at both the DCC and ORC for failing to properly invest in enough infrastructure despite repeated calls for more work to be done.

They said the DCC in particular had failed to keep pace with out-of-control growth as subdivision after subdivision in Mosgiel and Outram was approved.

The ORC was criticised for failing to properly maintain its flood protection schemes and for not coming up with an achievable solution to how flood-prone Henley could be protected.

Residents spoke of the frustration of dealing with flooding on a regular basis, with one Henley resident saying he was so fed up he and his wife planned to abandon their property.

Carlyle Rd, Mosgiel, resident Murray Hamilton said he had lived in the same house for 44 years and believed he had had sewage inundate his property 20 or 30 times.

He said the council was at fault for issuing consents for developments but failing to invest in infrastructure.

It’s not a lack of investment in infrastructure that’s the main issue, it’s why so much housing was allowed on a flood plain.

Developers have been allowed to make big bucks, and now residents are demanding all Dunedin ratepayers should now fork out for remedial work and flood protection.

Henley resident Kerrie Hooper, who was chest-deep in water when he left his property, questioned whether anything could be done to prevent serious flooding happening again in the flood-prone community.

After the meeting, he said he did not believe a solution was possible and he and his wife would likely abandon their property.

Another Henley resident accused the ORC of presenting Henley residents with a solution far too expensive for them to afford while ignoring cheaper solutions.

Henley has always been at risk of flooding.It is barely above sea level at the best of times, situated at the entrance to the lower Taieri Gorge, so when the flooding Taieri River hits the bottleneck the area floods, especially at high tide.

State Highway 1 used to go through Henley, but it was bypassed by what is known as the ‘flood-free highway’, a raised road specifically designed to keep out of the frequent floods.

It’s going to be very difficult to prevent flooding of residential areas across the lowest parts of the Taieri Plain, unless flood banks are built or bolstered.

It’s tough on residents, but they should have been aware of flood risks.

What shouldn’t be tough is the council figuring out where it’s a bad idea to allow subdivisions – a new subdivision at Outram was flooded last week.

RNZ:  Dunedin City Council to review zoning after Otago flooding

Flooding in new Otago housing developments is worrying and the council will look at all areas zoned for subdivision, Dunedin’s mayor says.

In Outram, on the Taieri Plain, the water pooled around houses in the new Anzac Court subdivision. Resident Craig Miller estimated it reached 20cm up the side of his house.

Dunedin mayor Dave Cull told Morning Report it was concerning to see some flooding in new subdivisions.

“I flew over the area on Saturday with [Minister for Civil Defence Nathan] Guy, and it did worry me that an area that is flooded now should have only partially-built homes on.”

How the fuck the possibility of this situation couldn’t have been foreseen escapes me.

Serious questions should be asked of city planners and resource consenters.

14 Comments

  1. artcroft

     /  July 27, 2017

    I had a civil engineer friend who worked on urban planning. He quickly realised that a knowledge of geology and hydrology was inconsequential. It was whoyouknowology that determined consents and what got built where.

  2. artcroft

     /  July 27, 2017

    I’m glad Cull’s not the Auckland mayor. Brown was bad enough.

  3. Live on flood plain. Get flooded out every so often

  4. Maggy Wassilieff

     /  July 27, 2017

    Yep, serious questions about ill-sited locations, and seriously underperforming infrastructure needs to be asked/investigated every time there is a weather “event”.

    Too often Councils rush to hide behind the “Climate Change” excuse, without divulging to the unsuspecting public that they know the area has always been flood-, fire- or erosion-prone.

  5. Geez, I had a look at the sea level rise maps…… Going to be a bit picky with the location of my forever home, resale value under 1m of sea isn’t going to be flash…..

    • Alan Wilkinson

       /  July 27, 2017

      I doubt you’ll be concerned about that at the current rate of increase of 3mm/yr. That’ll be in about 300 years time.

  6. sorethumb

     /  July 27, 2017

    Good post.

  7. Brown

     /  July 27, 2017

    I recall seeing maps of Wellington and Hutt Valley in the files I administered in my insurance role years ago. They were geotech / earthquake related and showed where the good, stable ground was, what was prone to flooding and what was old swamp and so on. I bought in sensible locations every time but suffered a very large landslip at a rental last year where the rain and earthquake in November combined to teach me a lesson (after about 65 years of stability) that I shouldn’t have needed to learn. It will be expensive but that’s just the price of getting one wrong and not the end of the world in a long game. The house itself is fine but the back lawn is gradually decreasing in size. It seems that as the good ground gets built on people revert to the land that was ignored (and for good reason) when development first commenced many years ago.

    • Gezza

       /  July 27, 2017

      I’m watching the far bank of the stream, which was straightened 20 years ago, regularly collapsing into the stream after every heavy rain. So far, the bank on my side is losing very little substance, thanks to some riperian plantings. But I can see that it is dropping away, and will erode to some extent.

      • Alan Wilkinson

         /  July 27, 2017

        Without erosion we wouldn’t have most of the South Island. Don’t knock it, G.

        • Gezza

           /  July 27, 2017

          Workers were in the stream a few months back, Al. Clearing blackberry & folage from the lower banks, claiming it contributed to collapses during flooding, which seemed a bit counter-intuitive. But the foreperson – who said they were doing phase 1, picking blackberries, 🍇 first 😀 – said that the top of my side of the bank would subside over time. It has, further North, where the fences have a lean towards the stream, & the concrete foundation of my fence is becoming exposed, so I need to add some fill there from time to time.

        • Patzcuaro

           /  July 27, 2017

          Erosion is fine provided it is somebody else’s backyard.

        • Patzcuaro

           /  July 27, 2017

          Tectonic plates moving together force the land out of the sea then it is eroded back into the sea in a cycle of life.