Flooding - West and Lower South Island - 2-4 Feb

[spwill]

1 in 100 year is just a statistical term
i.e the odds are it will be 100 years before it will happen again, as its a rare thing
but if you get the right setup occuring then it can happen again..and sooner (and some of the extreme setups are happening more regularly now)

The mid seventies through to the mid eighties was a significant period for significant flood events in the south of NZ.

1978 Mataura floods, 1980 Taieri Plains flooding, 1984 Southland floods were some of the events.

[Awhituobs]

yeah but were those 1 in 50 or 1 in 100 year events?

[NZstorm]

The mid seventies through to the mid eighties was a significant period for significant flood events in the south of NZ.

1978 Mataura floods, 1980 Taieri Plains flooding, 1984 Southland floods were some of the events.

I agree, some significant rainfall events in the 1970's and 1980's. 1980 event flooded and closed Dunedin airport for sometime. And the 1984 event flooded Invercargill airport. Have to look back at the rainfall numbers but 100mm + in 24hr type events.

A useful website here for looking back. http://www.nzextremerainfalls.com/

[spwill]

yeah but were those 1 in 50 or 1 in 100 year events?

A very quick google shows two of those events being called 1 in 100 years events, all three were high impact events regardless. With the Taieri Plains flood Dunedin airport was closed for 52 days due to inundation.

[Razor]

Thoughts are with people of Gore and Mataura right now as the evacuations are now being enforced.

Also saw a very sobering picture of Gunns Camp in the Hollyford. I think the true scale of this event is only just beginning to be apparent

Civil Defence Notice:

Gore and Mataura being evacuated

The Mataura River is continuing to rise and Emergency Management Southland require people in the low lying areas of Gore and Mataura to EVACUATE IMMEDIATELY.

Residents of Wyndham and Riversdale are being asked to prepare to evacuate, if required.

A map outlining the evacuation areas of Gore and Mataura is available on www.facebook.com/cdsouthland and www.civildefencesouthland.govt.nz

People should go and stay with friends and family on higher ground. Before leaving, check on neighbours and share this information if doing so won’t delay you. Call 111 if you are in danger.

If you don’t have a place to go, please evacuate to either the Calvin Community Hub on Robertson Street, or the Croydon Lodge.

In Mataura, transport will be available from the Presbyterian Church to the Edendale Presbyterian Church and the Christian Activity Centre.

Take a grab bag with you containing medication, clothing and personal items including documents.

If you are evacuating with pet, ensure they are contained on a leash or in a cage and that you have food for them.

Stay away from flooded areas until Civil Defence gives the all clear. Do not drive or walk through flood waters. The water may have washed away parts of the road and may contain debris. Tread all flood water as contaminated and unsafe

[Razor]

Gunns Camp, Hollyford

[Awhituobs]

woa..looks like it set like concrete?

[spwill]

yeah but were those 1 in 50 or 1 in 100 year events?

The Link NZstorm provided shows there were 3 in 100 year events in 6 years for Southland + the Taieri plains flood which is called a 1 in 150 year event within the 10 years mid seventies-mid eighties.

[Awhituobs]

I wonder then is there much use in calling these events by that sort of name?

[Chris W]

Just seen on Twitter that the Oreti River has overtopped its stopbanks at Wallacetown. Not surprising given what has already happened elsewhere. See here:

https://twitter.com/deane_ag/status/122 ... 11392?s=19

[Razor]

Personally I'm not interested in this sideline debate about 1 in 100 vs whatever. Its not important right now, perhaps you guys that are interested in that can move it to a separate discussion thread please?

I hope our southern membership and wider populace down there are ok. My Garston buddy who's familiy have been on the land there for 4 generations have never seen flooding like it in their hood. They put some simply staggering footage accross last night of getting stock to safety and mucking in for their neighbours. I was there just two weeks ago and its hard to comprehend the scale of what they are dealing with The southern spirit is alive and well and will be much needed today.

[Awhituobs]

I have lived and worked in this part of NZ before, so I do know this area well
Stay safe all involved

[spwill]

I wonder then is there much use in calling these events by that sort of name?

I guess you have to look closely at the numbers, each storm will be different with localised affects. The 1980 Taieri flood is obviously a very different area to the 1978 Mataura flood. Growing up down there in the south I do remember that active period of weather well and it has not been repeated for number of active events.

[spwill]

With the current event the heavy rain has been particularly widespread so a lot of water to come through river catchments.

[TonyT]

I did the meteorological analysis for the 3 "one in a hundred year" Southland flood events in the late 80s/90s for the government enquiry. Two of the storms were very similar weather patterns, but none of the three were like this current event. I know the return periods for river flows were being adjusted (as they should be regularly) so it would be interesting to see what numbers come up this time around. I get the feeling this will have lower rainfall return periods but potentially higher river flow return periods, but thats only a guess.

[NZstorm]

With ther way the southern jet stream has been so rampant this summer, there was always going to be an event or two like this.
The event in December was particularly spectacular with the spill over storms. Looks like the southern jet is finally backing off now.

[wembley]

I read a book on the October 1978 floods years ago, now that was nasty.

Also there was a photo of Dunedin Airport in June 1980 with all the cars in the parking lot moved onto the runway to escape the floodwaters.