Alarm at more Dunedin flooding

In June 2015 a surprisingly bad storm caused bad flooding in the reclaimed but still low low lying south Dunedin area. In the aftermath there were admissions of poor maintenance of drainage systems (storm water drains, mud tanks, screens and pumping stations). Changes were made with assurances things would work better in the future.

A near record 160.2 mm of rain fell in a day then.

Leading up to yesterday, in January this year, there was low rainfall of 26.4 mm (at the University weather station), and most (16 mm) of that was in one day two weeks ago. Things were very dry.

There was ample warning of impending heavy rain, so there was plenty of time to be properly prepared. Yesterday there was 109.6 mm of rain, significantly less than when the 2015 floods happened.

But there was still serious flooding in south Dunedin, not as bad as in 2015 but bad enough to have a state of emergency to be declared and for homes (and a rest home) to be evacuated.

ODT: Stormwater system overwhelmed

Torrential rain overwhelmed Dunedin’s stormwater system yesterday, flooding parts of Mosgiel and South Dunedin and sparking evacuations and road closures.

History repeated itself for many residents, who faced similar flooding in 2015 and wake this morning facing  another clean-up. A state of emergency was declared at 2.20pm. Dunedin  had received 18mm of rain an hour in the previous two hours.

“That is more than our system is designed to cope with, even though it has operated exactly how it is intended to,” Mayor Dave Cull said.

This is an alarming admission.

South Dunedin’s stormwater system was unable to cope with the 2015 deluge, and struggled with the amount of rain which fell in a short time yesterday.

“It was just the sheer volume of rain in such a short period of time meant that some of the groundwater entered the wastewater system, and that’s what caused the problem,” Civil Defence controller Leanne Mash said.

So two and a half years after major floods in part caused by poorly maintained drainage systems, the improved drainage systems still can’t cope with just two thirds of the rainfall.

This is alarming, not just for those who were directly affected by the flooding, but also by at least one ratepayer, me.

How bad will flooding be if we get a repeat of the 2015 rainfall?

Labour, National up in One News poll

In the first One News/Colmar Brunton poll of the year Labour are up six to 31% and National are up four to 49% – this is a similar result to they recent Roy Morganl.

  • National 49% (up 4)
  • Labour 31% (up 6)
  • Greens 10% (down 2)
  • NZ First 6 (6% (down 2)
  • Maori Party 2% (no change)
  • Conservatives 1% (down 3)
  • Refused to answer 3% (down 2)
  • Undecided 7% (up 2)

Those results are round to the nearest percent so aren’t very accurate for the smaller parties.

Polling was done over 14-18 February so covers only a small part of the difficult week for Andrew Little.

Poll link.

This week’s Roy Morgan results were very similar:

  • National 49%
  • Labour Party 30%
  • Greens 12%
  • NZ First 6%
  • Conservative Party1.5%
  • Maori Party 1.0%

Colmar Brunton Preferred Prime Minister:

  • John Key 41% (down 2)
  • Andrew Little 12% (first result)
  • Winston Peters 7% (up 2)

Labour up, National down in Roy Morgan poll

The latest Roy Morgan poll:

  • National 49% (down 3%)
  • Maori Party 1.0% (down 0.5%)
  • Act NZ 0% (down 1%)
  • United Future 0% (unchanged)
  • Labour Party 30% (up 4% – their highest level of support since July 2014)
  • Greens 12% (up 1%)
  • NZ First 6% (unchanged)
  • Conservative Party1.5% (down 0.5%)
  • Internet-Mana Party 0% (unchanged)
  • Independent/ Others 0.5% (unchanged).

This poll was held on February 2-15 (the previous one was (January 5-18, 2015) – most of the polling will have been done during John Key’s awful week last week and before Andrew Little’s awful week this week.

Labour will be hoping this recovery trend continues. If they’re lucky their hiccups this week will be forgotten by the next polling period.

RoyMorgan2015February2-15

And Government confidence is down.

Coinciding with the decrease in support for the Government the latest NZ Roy Morgan Government Confidence Rating has fallen significantly to 124pts (down 20pts). This is the lowest the NZ Roy Morgan Government Confidence Rating has been since October 2013.

Coinciding with the decrease in support for the Government the latest NZ Roy Morgan Government Confidence Rating has fallen significantly to 124pts (down 20pts). This is the lowest the NZ Roy Morgan Government Confidence Rating has been since October 2013.

Roy Morgan includes good ‘margin of error’ information:

Margin of Error

The margin of error to be allowed for in any estimate depends mainly on the number of interviews on which it is based. The following table gives indications of the likely range within which estimates would be 95% likely to fall, expressed as the number of percentage points above or below the actual estimate. The figures are approximate and for general guidance only, and assume a simple random sample. Allowance for design effects (such as stratification and weighting) should be made as appropriate.

Sample Size Percentage Estimate
40%-60% 25% or 75% 10% or 90% 5% or 95%
500 ±4.5 ±3.9 ±2.7 ±1.9
1,000 ±3.2 ±2.7 ±1.9 ±1.4
1,500 ±2.6 ±2.2 ±1.5 ±1.1
2,000 ±2.2 ±1.9 ±1.3 ±1.0

The Roy Morgan sample size this poll was 891.