NZ Weather Forum

Manukau heads obs wrote:how come TV1 breakfast show the reporter said only 75mm total over the 3 days when it was over 100mm?

Sounds like they used the airport figures. Going by the Chch page, the Lyttelton site got 180mm over three days... 170mm of that in just two days.

Manukau heads obs wrote:how come TV1 breakfast show the reporter said only 75mm total over the 3 days when it was over 100mm?
also how come they are trying to say even M/S was unprepared?
I saw lots of warnings go out prior (i.e heavy rain , accumulations to 150mm about banks pen. and areas exposed to south (i.e CHCH)

The know-nothing man-in-the-street likes to claim the Metservice is always wrong, despite it being right most of the time. TVNZ's bosses are desperate to appeal to the majority (and most TV execs are know-nothings) so they join in the MS-bashing melee at every opportunity.

Remember the June 2006 snow? The MS admitted up front it was as surprised as anyone at the extent of it, even though average snow depths were no greater than most years and less than many, yet it was caned so hard by every gumby and his dog that to this day the service deliberately overstates snowfall risks, simply because being wrong in that case is somehow seen to be "not as bad."

As far as I Know M/S never had a rain warning out for chch just a watch.

4th & 5th bullet points emphasise the major contrast between different parts of the city from this event.
__________________________________________________________________________________________

Orion media statement – 10.00am, 6 Mar 2014

Progress being made on restoration of power

• At 10am approximately 700 customers are without power.
• Customers without power are mostly around Banks Peninsula, although some parts of Christchurch and an area around Southbridge also remain without electricity.
• Flooding, slips and water logged ground in the hills is either preventing access to our network or making repair difficult.
• For safety reasons and to limit damage to assets, we have turned off power to 5 kiosks in Christchurch due to flood waters. The number of customer outages this caused was reduced by our switching of load from others parts of our network to the affected areas. However, around 50 customers remain without power as a result of the need to turn off power to these kiosks. The majority of these are around the Avonside Drive/Linwood Avenue area. These customers will remain without power until flood waters recede and the kiosks can be dried and checked. Given the level of the ground/river around Avonside Drive, it may be that flooding does not recede in time for power to these customers to be restored today.
• It is quite likely that some other individual customers will be without power overnight tonight given access issues and the number of repairs to be undertaken. Our priority is to work on those repairs which impact the most customers first. As the day progresses we will progress to repairs that affect only a few customers at a time. During this stage of the repair effort it is a slow process reducing the number of customers without power as many of the repairs only affect one or a few customers but still take many hours to complete.
• Anyone who sees a fallen power line should stay well clear and call us on 0800 363 9898 immediately.

• We recommend that anyone whose house or business has been flooded to have their electricity wiring checked by a registered electrician. Particularly if flood waters have reached the levels of plugs.

An update on the number of customers without power will be placed on our website, http://www.oriongroup.co.nz, at midday and again at 2.00pm today. Our next media statement will be at 4.00pm today.

As far as I Know M/S never had a rain warning out for chch just a watch.

In addition, heavy rain is expected about Banks Peninsula from early
Tuesday morning through to Wednesday morning. The heaviest falls are
expected about higher parts of the Peninsula and places exposed to
the south, where 130 to 150mm could accumulate, possibly causing
slips and surface flooding.

I would rate the area just west of the port hills, that is exposed to the south,i.e the city area, being covered by this warning

Then why in there watch did they state this is for Chch city if it you think it was covered under the warning.

melja wrote:Then why in there watch did they state this is for Chch city if it you think it was covered under the warning.

The watch stated:

Significant rain is also expected for Christchurch from Tuesday
morning through to Wednesday morning and a Watch remains in force as
accumulations may approach warning amounts and flooding is possible
around parts of Christchurch City.

Warning criteria is 100mms in 24 hours. I think MS got it right in this case but unfortunately, post quakes, the land is in the affected areas now looks more prone to flooding.

Then in no way can this be called a 1/100 year flood then, a quick search found several examples of worst rain than this
"Falls of more than 100 mm of rain in 24 hours are not unusual and up to 170 mm in 18 hours has been recorded" this from NIWA and also " Also worthy of note is a storm in October 2000 in which 133 mm of rain was recorded in 12 hrs "

the media has called it that...I dont see anyone else calling it a 1 in 100 year rain event

It seems to me that the land itself has been affected by the quakes, whether in consistency or by sinking, and may be more prone to flooding from rainfalls that wouldn't have caused so much disruption in the past.
I believe I heard that the stormwater drainage system is not yet up to capacity post-quakes?
I wish people wouldn't drive through causing bow-waves!
The flooding has been heart-rending to see and I'm very sorry for those who have been affected.

yes, residents in worst affected flooding areas say they now get regular flooding problems
some areas have sunk 0.4m...thats huge...

Manukau heads obs wrote:the media has called it that...I dont see anyone else calling it a 1 in 100 year rain event

Actually, it was the Mayor who called it that in a Press release yesterday, along with Coucil officials. As well as the rain it combined with the end of summer (ie hard, dry ground- more runoff) and a high tide coincided with the final peak of the rain

Add this to the EQ effects, and you have a recipe for a major problem

ok, the ducks might have lined up badly
but in isolation for the rain event as such.....

It feels like although there is progress going on around the city which is fantastic, but what is being done is also being rushed and not thought about the affects long term.
All this we will rebuild the land back up is like slapping a plaster over the issue in the hope the city will settle, when long term its only going to happen again.
This is what happens when you build on top of a swamp, the simple answer is and although its such a widespread issue that will take time and money is you have to knock down these suburbs and return the land to swamp.
Out west is far more stable land and has certainly been proven, but how do you relocate thousands of people its a tough one.
Remember the plains were here developing well before us and the settlers came along and diverted rivers to building suburbs and built the land up, as I always say build with nature not against it.

yes as "orion" said exacerbated by the quakes,pretty sad for chch,wonder when it will be fixed for some people.

melja wrote:Then in no way can this be called a 1/100 year flood then, a quick search found several examples of worst rain than this
"Falls of more than 100 mm of rain in 24 hours are not unusual and up to 170 mm in 18 hours has been recorded" this from NIWA and also " Also worthy of note is a storm in October 2000 in which 133 mm of rain was recorded in 12 hrs "

There were some big rainfalls in April 1968, shortly after the Wellington events. Mt Pleasant had 135mm on the 10th, with about 340mm for the month, and Hickory Bay had 705mm for the month. The site at Onawe had over 200mm on the 10th.

Found this from a Chch city council hazard report from 2003

"Christchurch does not experience the intensity of rainfall that occurs in other parts of New Zealand. Generally, 24-hour rainfall with return periods of five years produce 50 -100 millimetres on the plains and 100 - 150 millimetres on the Port Hills."

So at a guess they put that 1/100 event wording out there to cover there butt and make everyone think it was extreme rain and not there lack of action on fixing there storm water systems post EQ.

NIWA's more central Kyle St site recorded 152mm for this event, with 123mm of that falling in the 24 hrs to 9am on Wednesday, compared to Chch Aero's 81mm and 59mm respectively.

123mm in 24 hours is nothing to sneeze at , thats for sure

Manukau heads obs wrote:123mm in 24 hours is nothing to sneeze at , thats for sure

I agree. Maybe a 1/50 year event but could be more for that area.

The highest 24 hr rainfall period for NIWA's Kyle St site was actually 136mm to 1pm on Wednesday.