1999 Thames/Coast Expert Sea Flooding Advice Ignored

1999 Report Laid Out Comprehensive Plan 

 

In many recent blog posts and articles in the Hauraki Herald I have been pointing out the urgent need:-

  • to identify all coastal hazards including coastal flooding on a site-specific basis.
  • to prioritise the areas which are most at risk from coastal flooding particularly on the western side of the Peninsula,
  • to take account of storm surge and wave effects
  • for a close partnership between the Regional Council and the District Council
  • for community consultation and engagement.
  • to comply with RMA, and the New Zealand Coastal Policy Statement.

 

1999 Report coastal flooding risks

It turns out that these very same arguments and the call for action were made in a very forthright manner nearly 20 years ago.  In 1999 coastal scientist Jim Dahm wrote a report for the Waikato Regional Council in which recommendations were made on all of these issues. But very few if any of his recommendations relating to coastal flooding have been implemented by either the Regional Council or the District Council.  Almost 20 years later this problem is either being ignored or finger-pointing is engaged in suggesting that it must be someone else’s problem.  Nearly 20 years have been wasted.

Here are some of the more telling quotations from the 1990 report.

The development and implementation of site specific mitigation strategies will incorporate hazard mapping and risk assessment, development and implementation of appropriate hazard management measures “

“The potential impact of predicted, human-induced global warming might also aggravate existing coastal flooding hazard in the future. Particularly through an acceleration in the rate of rise of mean sea level and possible changes in the nature, frequency and magnitude of coastal storms.”

In recent decades, the most significantly affected coastal settlements have been Thames, Moanatairi (a suburb of Thames), Tararu, Te Puru, and Waikawau along the eastern margin of the Firth of Thames, Kaiaua on the western margin, and the eastern Coromandel settlements of Whitianga and Tairua. Other settlements that have also been affected to a lesser degree include Thornton’s Bay, Waiomu and Te Mata along the eastern margin of the Firth of Thames. “

“The NZCPS also directs that policies and plans should recognise the possibility of a rise in sea level and should identify areas, which as a consequence would be subject to erosion or inundation.”

“Mapping of hazard risk areas

In the Waikato Region, definition of the risk from coastal flooding at any particular site generally requires information on the:

  • magnitude and frequency of flooding associated with coastal storms (particularly the annual probability of various flooding levels associated with the combination of astronomical tides and both storm surge and wave effects);
  • potential effects likely to accompany predicted global warming (e.g. rise in mean sea-level, change in magnitude and frequency of coastal storms and associated storm surge and wave effects)”

“Priority For Work

The highest priority work is to further improve design information in regard to coastal flooding in the Firth of Thames. Recent work has improved existing information in respect of design flooding levels arising from the combination of astronomical tides and storm surge. However, further information is required on the magnitude and frequency of wave effects (e.g. wave set-up and run-up) to improve design level estimates.”

“Site Specific Risk Mitigation Strategies

Site specific risk mitigation strategies should be developed for flood prone areas on a prioritised basis. These strategies will need to incorporate:

  • hazard mapping and risk assessment
  • development and implementation of appropriate hazard mitigation measures
  • appropriate monitoring and evaluation.

Partnership Between Councils

“As envisaged in the proposed RPS, a partnership is proposed for the development, implementation and monitoring of site specific strategies. Broad details of the relevant roles and responsibilities of Environment Waikato and district councils are as outlined in the RPS and the flood hazard mitigation strategy, with exact details of the partnerships to be resolved on a site by site basis. “

Community Engagement

However, as noted further below, considerable emphasis should be given to community awareness and participation in the development and implementation of strategies for the mitigation of coastal flooding risk. This is critical to increase the preparedness of communities in flood prone areas and to empower them to accept greater responsibility for risk reduction.”

So there you have it – a very detailed blueprint from 1999 as to how we need to

  • take the threat of climate change seriously,
  • provide detailed hazard mapping of coastal flooding areas,
  • prioritise the areas for work,
  • carry out site-specific mitigation strategies,
  • make sure there is a strong partnership between councils and proper and effective engagement with local communities.

It’s a sad indictment on our Councils that 18 years later these recommendations have not been acted upon.  It’s well overdue for the delay, denial, and finger-pointing to end.  We need to get serious and tackle these issues urgently.

In case we needed any reminding about the need for action – this photo was taken on 23 July 2017 at the Thames marina. The tide has invaded the entrance road to the marina.  There was no storm surge or wave effects, and barometric pressure was normal.  Now imagine 0.5 m, 1 m or even 2 m above these levels, plus a storm surge and low-pressure system and you can begin to see the challenge we are facing with the potential sea level rise in coming decades.

20170723_184026

 

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2 thoughts on “1999 Thames/Coast Expert Sea Flooding Advice Ignored”

  1. Frustrating for us all. What is the general consensus now about the level of actual rise? Last time i researched was some 25 years ago and the gist was that the main component related to expansion of the top few metres of sea. Back then I hazarded around 850mm to 1.2m.

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    1. During the satellite era (1993–2015), relative sea level rise at Auckland has averaged 4.9 mm a year in comparison to the Global Mean Sea Level rate of 3.3 mm a year. The Tararu gauge near Thames indicates a relative sea level rise of 6 mm a year in the satellite era (1993–2015).

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