Rain, floods and a major bridge washout on the West Coast

Heavy run is normal on the West Coast, but they are currently getting more than usual, with floods road closures from Makarora (just north of Lake Wanaka leading over the Haast pass) to Hokitika.

And there has been a major bridge collapse on the Waiho river just south of Franz Josef township – this is the only road  between there and Fox Glacier.

Civil Defence West Coast

 

1 News:  Astonishing footage captures bridge collapse in Franz Josef as wild weather batters West Coast

The river doesn’t look particularly high, but has been flowing very strongly with boulders and ice chunks likely to have damaged the supports.

Might need to go a bit faster than 30 to get across that gap.

It could take quite a bit to get that river crossing and therefore the only highway re-opened.

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There is currently one road closure, SH6 Franz Josef to Fox Glacier with two slips at Omoeroa and significant surface flooding south of Whataroa at Lake Wahapo. Please watch the NZTA Website for any developments at:

Latest Update:  26 March 2019 8:42 pm

There is a raised risk to life and injury for local residents and further risk to property, and accordingly the Mayor Bruce Smith has declared a State of Emergency for the Westland District.

The Waiho Bridge has been completely destroyed. NZTA will be assessing how to reinstate the Highway following this disastrous event. The ECC will be assessing the need for a controlled evacuation on the South Side of the Waiho River.

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24 Comments

  1. Zedd

     /  26th March 2019

    scary stuff.. I still clearly remember the Sth Dn flood in 2015.. the Leith nearly bursting its banks; could be ‘EVIDENCE of Climate Change’ ? :/

    Reply
  2. Duker

     /  26th March 2019

    So Bridges was promising 10 bridges for Northland yet that single lane ancient structure was the only road past the town ?

    One flood doesnt make climate change- as you dont seem to know that ‘climate is the 22-30 year average of weather’
    Whats your 30yr flood data for the Waiho River ?

    in the US midewst they are having large floods beacuse …. they have a severe winter which had heavy snowfall which froze the wet ground and then rains have melted the snow. Is that climate change too- heavy snow ?

    Reply
    • Griff.

       /  26th March 2019

      Basic physics warmer temperatures equals more moisture can be carried by the atmosphere.
      Hence in a warmer climate you will see increasing extreme rain fall events .,,,,,,,

      Snow is just frozen rain so yes we expect to see and have measured extremes of snow fall increasing in some places . The USA mainland might have been cold but that is not where weather systems get moisture from is it son,

      Due to our position and weather patterns NZ rainfall data is too noisy to expect to see a statistically significant trend emerging from the historic data for decades yet.

      Reply
      • Duker

         /  27th March 2019

        0.5C increase in mean daily temperature.
        Anyway west coast is in South Island gets lots and lots more rain than warmer Northland, which is ironically more prone to drought . So the ‘basic physics’ you talk about – while correct in a glass jar in the lab- doesnt mean much when it comes to weather some places in NZ and its long term average , the climate.
        California was supposed to become ‘permanent drought according to some, hasnt happened. They have of course a long historical record of occasional severe long lasting droughts.

        Reply
        • Kitty Catkin

           /  27th March 2019

          Snow isn’t just frozen rain, look at the shape of it. It’s crystals.

          Reply
          • Kitty Catkin

             /  27th March 2019

            Frozen rain is sleet, I think.

            Reply
            • Frozen rain is hail. Sleet is partly melted snow usually mixed with snow and rain.

            • Kitty Catkin

               /  28th March 2019

              Sleet is disgusting, the worst of both. Not pretty like snow or useful like rain.

  3. Kitty Catkin

     /  26th March 2019

    Thank goodness nobody was on it.

    This isn’t Northland, it’s the West Coast of the South Island.

    Reply
  4. Maggy Wassilieff

     /  26th March 2019

    Waiho in flood – 1931
    http://nzetc.victoria.ac.nz/tm/scholarly/tei-Gov06_04Rail-t1-body-d9.html

    Recent behaviour and sustainable future management of the Waiho River, Westland, New Zealand
    Journal of Hydrology (New Zealand)
    Vol. 52, No. 1 (July 2013), pp. 41-56

    https://www.jstor.org/stable/43945043?seq=1#page_scan_tab_contents

    Reply
    • Griff.

       /  26th March 2019

      [Deleted – any more personal targeting like this and you will be put on auto-moderation. PG]

      From your link ,

      In March, after those ten inches of rain, the Waiho was running a banker. More than a banker, in fact, for the treacherous flood was soon eating out the banks on the southern side, and before nightfall several chains of metalled road had been swept away. Late in the afternoon we trooped out to see the damage

      10 inches is 250mm .
      A mere shower.
      Met service is predicting over 700mm for some regions of the west coast.

      Reply
      • Alan Wilkinson

         /  26th March 2019

        As kids I remember a summer holiday trip on the West Coast. First dad pulled over to let a car pass in the Buller Gorge and the trailer we were towing slid off down the hillside while the car hung onto the road with two wheels as the road verge gave way. Farmers with tractors winched everything back on the road. A day or so later he’d brought a pup tent for us kids to sleep in and it rained West Coast rain that was like standing under a waterfall. All the tent did was to turn it into a descending mist so we spent the rest of the trip sleeping in the car at night. When your annual rainfall averages approaching 7m you know this stuff is not for the faint hearted.

        At the other extreme we experienced a flood in Adelaide when it got just 25mm overnight. Although that’s a laughable amount in NZ, when it falls on a hinterland as vast as Australia’s it becomes a major problem.

        Reply
      • Duker

         /  27th March 2019

        Franz Joseph rainfall in march ?
        yesterday they got 113 mm – ( I choose Franz Joseph but Metservice gave me Haast!)

        The mean total is about 400mm but that can be expected to reach 700mm in 1 year in 10.
        Thats not even the highest as its at the coastal strip , go inland and higher altitudes and that can double that .
        Tuke River can get 11m of rain on average , so some years much more.

        Reply
      • Kitty Catkin

         /  27th March 2019

        Griff; we have had less than 1/10 of that this YEAR ! 70+mm so far; 1/3 of the usual.

        Reply
    • Duker

       /  27th March 2019

      Maggies link essentially says the gravel load down the river in flood raises the river bed level so that over topping stop banks and damage to bridge abutments will be more common.
      we see that in the pictures, will happen again sometime in next 10 years

      Reply
  5. Reply
    • Kitty Catkin

       /  27th March 2019

      300-400mm. Hamilton’s had 74mm all year.

      Reply
      • Duker

         /  28th March 2019

        Last year Hamilton had 217 mm for March alone

        Reply
        • Kitty Catkin

           /  28th March 2019

          Good grief.

          We had a bit last night, but not enough to register in the rain gauge; I looked out at it this morning.

          The rainfall so far this year is about 1/3 of the usual.

          Reply
  6. Maggy Wassilieff

     /  28th March 2019

    Debris, a rising river bed and floodwaters caused a West Coast bridge’s collapse:
    https://www.stuff.co.nz/national/111624525/worst-storm-to-hit-west-coast-in-37-years-leaves-trail-of-destruction

    Reply

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