Flood barrier added to Whanganui’s North Mole upgrades after safety concerns

A fishing platform downstream of Tregenna Street as part of the North Mole upgrades. Photo / Kahurangi Simon

Fears for people’s safety from flooding have prompted further upgrades to Whanganui’s North Mole reconstruction, but some residents are concerned about losing their views of the Whanganui River.

The North Mole upgrade works, which are 75 per cent completed, are part of Te Pūwaha, the Whanganui Port revitalisation project.

A Horizons Regional Council meeting last week, also attended by Whanganui District Council representatives and Te Mata Pūau (a collective of hapū representatives), considered three options to improve amenities, enable flood protection and enhance the area as a community space.

The upgrade decided on was a 4.1-metre embankment to protect from floods, with a recreational area for families that will have a cycleway and picnic tables between fishing spots. The height of the embankment would enable 100-year-level flood protection. It also has extra height to account for climate change and an allowance for freeboard.

“It’s not a matter of if the river will rise to high levels, but when,” Whanganui-based Horizons councillor Alan Taylor said.

“While I acknowledge that amenity views of the awa will be lessened, if the recent devastation of Cyclone Gabrielle has taught us anything, it’s that we need to be as resilient as possible to climate change.”

Whanganui’s other Horizons councillor, David Cotton, said he hoped the recreational area would provide a solution for the “small pocket of residents” who had voiced concerns about losing views.

“What was once a somewhat-neglected public space will receive a makeover, making it a safe place for families to fish and to connect with the awa, while also protecting residents and their homes from flooding.”

Horizons group manager of catchment operations, Dr Jon Roygard, said the council’s flood modelling revealed the depth of inundation predicted in a 100-year flood event would impact around 15 houses if flood protection for the area was not completed alongside the upgrade.

The strengthening of the South Spit erosion has been re-prioritised due to the likelihood of the river breaching the spit and outflanking the South Mole.

“The aim is to complete the remaining works over the coming months, noting some things like establishing grass may be completed in spring,” Roygard said.

The North Mole is 75 per cent completed, but aspects of the mole rock wall are still under construction, including the two fishing platforms and stormwater outfalls.

Horizons councillors decided to continue delivery of project works under Te Pūwaha within the currently approved $16.4 million budget, with the short-term priority being the completion of the North Mole works and consenting and procurement for the Tanae Groyne.

“The river training structure upstream of the Tanae Groyne (South Spit) has been reprioritised, and further investigation, design and approval of these works is planned over the next year. The remainder of the budget is to be allocated to the South Mole,” Roygard said.

For the construction of the South Mole, a further year of work is required and Horizons will have to search for extra funding. It had “directed officers to progress conversations with both Whanganui District and central government to see if other funding can be sourced”.

“Council agreed to do a partial rebuild of the South Mole at an approximate height of 2.3 metres to enable future upgrades to build on the structure,” Roygard said.

The primary purpose of the South Mole upgrade is to ensure a navigable depth will be maintained for vehicles accessing the port.

Roygard said Horizons was due to meet with Tregenna Street residents on Tuesday, April 4 to further discuss the construction plan, with Te Mata Pūau there to support the community.