New Zealand: Extreme floods could be annual 30 Apr 12;

Extreme floods which usually only occur once a century could eventually happen every year as sea levels rise, National Institute of Water & Atmospheric Research (NIWA) says.

New Zealand needs to start preparing for that possibility now - before it’s too late, NIWA’s principal scientist Rob Bell said.

Once sea levels have risen by half a metre, once in 100-year flooding events could occur annually, Bell said.
Higher storm surges could damage beaches, seawalls, buildings and roads and may affect drinking water, Bell said.

When the half a metre rise will occur is uncertain, but Bell said a one metre rise by 2100 could not be ruled out.

It was crucial that councils started thinking about the risks as sixty-five per cent of Kiwis lived within five kilometres of the sea, Bell said.

They needed to consider the rising sea levels when thinking of where to build a road, or where to place a footpath, he said.

A new road may last for only 40 years if it is not built in the right place, but if it is built with the rising sea levels in mind, then it could last much longer, Bell said.

“It’s mostly about risk…New Zealand’s Coastal Policy Statement directs that we also avoid further increasing risk in the future.

“So for large new subdivisions and developments, we should be building into this new development sufficient capacity to absorb even higher rises in sea level, given the permanent nature of subdivisions."

What needs to be done to mitigate the risks will be the subject of a two day conference in Wellington next week.

One of the guest speakers will be Tim Reeder, who will discuss how his team has adapted to sea-level rise in the Thames Estuary in the United Kingdom.

Scientists warn of sea-level dangers
Amelia Wade New Zealand Herald 1 May 12;

Sea levels are rising and scientists warn that action is needed to reduce risks of damage. Photo / Supplied
Sea levels are rising and scientists warn that action is needed to reduce risks of damage. Photo / Supplied

The sea level is rising and scientists warn that action is needed to minimise the risks of flooding, damaged beaches and infrastructure and infected drinking water.

Sixty-five per cent of New Zealanders live within 5km of the sea, including 12 of the country's 15 largest towns and cities.

And with a sea-level rise of at least one metre predicted, storm surge flooding will start to occur in those areas more frequently on king tides, the National Institute of Water and Atmospheric Research says.

Principal scientist Rob Bell said that because of their preference for coastal living, New Zealanders needed "to really consider what rising sea levels mean for us", especially for higher tides.

Dr Bell said it must be determined which coastal areas were the most vulnerable.

As well, new developments and subdivisions must start to take into account the rising sea-level.

Higher storm surges could damage beaches, seawalls, buildings, roads and other infrastructure; they might also affect drinking-water supplies in lowland rivers and groundwater, he warned.

A report by Niwa and Victoria University last year looked at how the predicted sea-level rise would affect the Mission Bay and Kohimarama area in Auckland.

It found that even with conservative predictions of how much the sea would rise, it would present a "significant risk to the people and property" of the community, especially during storms.

The New Zealand Climate Change Centre is holding a two-day conference at Te Papa in Wellington next week to discuss the "growing concern".

As well as a speech from Dr Bell, there will speakers from the British Environment Agency, Massey University and oceanographer John Church from the Centre for Australian Weather and Climate Research.

Scientists will present a synthesis of recent projections for sea level rise, discuss the uncertainties associated with these projections and will identify anticipated impacts on New Zealand's coastal environment and infrastructure resulting from climate change.

Said Dr Bell: "Planners and engineers here in New Zealand need sound guidance on what sea level rises are expected along our shores, working around the key uncertainty about how quickly the polar ice sheets may melt in future."