Rising sea predicted to hit 1200 homes

More than 1200 Tauranga homes lie less than 1.5m above the spring tide mark, making them susceptible to rising seas, a new report has found.

The Preparing New Zealand for rising seas report, released this month by the Parliamentary Commissioner for the Environment Dr Jan Wright, found there were 1231 Tauranga homes within 1.5m of the spring tide mark, 107 businesses and 35km of roading.

Mayor Stuart Crosby said doing nothing was not an option. The council would next year begin two-dimensional mapping on the potential impacts of rising sea levels and sink bores to test groundwater levels.

Once the data had been collected the council could start to look at the options. He expected decisions in about five years. "The community needs to know with a degree of accuracy what is going to happen."

Dr Wright's report said that most of Tauranga's low-lying homes were in Mount Maunganui, Otumoetai and Matua and the low-lying businesses were near Tauranga Airport.

Research found the Western Bay of Plenty region needed to prepare for a sea level rise of 1m over the next 100 years. Three types of coastal hazards were exacerbated by rising sea levels - flooding, erosion and groundwater rising too high or becoming saline.

Erosion was a natural ongoing process, however, the process had increased through the impacts of humans and climate change - including rising sea levels and extreme weather events.

Western Bay of Plenty District Council recently partnered with Tauranga City and Bay of Plenty Regional councils to commission a study by Opus on the coastal erosion risk at 28 sites across the Tauranga Inner Harbour, and the financial viability of mitigation measures.

The study was sparked by increasing pressure on councils to allow new more intensive clifftop and shoreline development.

As part of the study an estimate was made of the degree of damage to property and infrastructure that may occur over the next 100 years, taking into account the predicted climate change and how that may change current erosion rates.

The report ranked the sites in order of priority and cost to fix. Snodgrass Rd ranked number one as being at a high-risk, with the next four - Matua, Maungatapu West, Omokoroa West and Maungatapu Marae - all medium-high risk.

The report also identified that a number of the sites may be at risk of extensive flooding through changing wave impacts and was an important area for further study.

Western Bay Council will seek public input on a 30-year policy for harbour and coastal erosion through an online discussion on its website. The policy, once finalised, will specify where and how the district responds to erosion.

Engineering and projects manager Peter Clark said the council wanted to avoid the mistakes made in Christchurch where, without consultation, a notice about the potential for erosion was put on all coastal residents' LIM reports, making it difficult for home owners to sell their homes.

Lindock Ave resident Carol Ballard said she had been living in her property on the water's edge for more than 33 years and it had not changed over the time period.

She was not worried about the new predictions either, she said.

"According to experts it should have risen already."

Western Bay of Plenty District Council Mayor Ross Paterson said the rising sea level was not a huge issue in the Western bay but they were taking the matter seriously.

There were concerns for certain areas but new building consents would take place on higher floor levels, he said.