Time for coastal planners to take climate change seriously


For the people trying to get away from Ex-Tropical Cyclone Fehi’s storm surge, it was all too real. For the people in small coastal towns along the West Coast watching the angry seas smashing what in some cases were the only roads in and out of their townships, the thoughts of being cut off must have been nerve wracking. As communities clean up and look to the future, it is time to ask just how good are the contingency plans for future storms, and whether planners have made adequate provision for such events.

Given that high intensity but relatively short duration storm events seem to be becoming a regular occurrence, how well prepared are we for the effects of climate change on the marine environment including how oceans contribute to storms? In January 2017, we had a “weather bomb” of highly damaging winds and substantial heavy rain in the Southern Alps; Cyclone Debbie, which caused widespread flooding in the Bay of Plenty; Cyclone Cook, which tracked quite quickly past New Zealand, without directly crossing the country. There was also several significant winter storms.

There were a number of facets of ex-Tropical Cyclone Fehi that I found concerning as someone who has studied natural hazards:

  1. Granted it was only a Category 1 Tropical Cyclone, Fehi’s relatively rapid evolution from a tropical depression in the Coral Sea to a
  2. Despite having lost its status as a Tropical Cyclone, the remnants of Fehi still managed to kick up 150km/h winds. It still managed to drop over 200mm of rain in a day and in some cases up to nearly 300mm
  3. The storm surge – granted it was exacerbated by king tides caused by a rare blue super moon – was punishing in many small settlements such as Ngakawau, Granity and Hector on the West Coast, north of Westport

It is true that councils have started planning for climate change on the coastal environment and the elevated risk posed by storms. Some communities are having to turn to their ratepayer base for more money to help fund expensive coastal works, such as sea walls and helping maintain existing natural features such as sand dunes.

Over the last 20 or so years I have been watching the tidal gauge charts at Lyttelton that have been appearing in The Press. 20 years ago, the lower end of the range was 0.1m and the top end of the range seemed to be consistently around 2.5 metres on king tides. Outside of that, the range could be as small as 0.5m-2.0m. Today in 2018, the range seems to be between 0.1m-2.7m. I am not necessarily suggesting this is due to changes in sea level – it could simply be that the tidal gauges today are better calibrated to detect more minute changes, and thus 0.1m-2.7m +/- all along.

This is important to know because hazard planners plan for the worst case scenario – and hope that reality is something a bit less severe. The worst case scenario would presumably be a storm – not necessarily a tropical cyclone, as a deep low pressure system with its origins in the Southern Ocean can cause much damage – with a surge, coinciding with king tides. Such a storm happened last week.

Moving forward, the damage caused by Fehi, aside from causing insurance companies and Civil Defence much grief, also kick up some serious planning issues. Are, for example, Regional Plans adequately tooled to deal with land zoning issues that may arise from coastal properties no longer being suitable for occupation? Does the New Zealand Coastal Policy Statement pay the due regard now needed to coastal hazards and climate change? And given Fehi could have been a stronger Cyclone, but mercifully was not, was what happened last week really a taste of the “worst case” scenario?

It is time to start asking and attempting to answer these questions.

 

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