Cyclone Gabrielle: Digger sent to stopbank spillway at Waiohiki and why it has angered Pakowhai residents

A swathe of silt surrounds Pakowhai homes after they were hit by flooding without warning. Photo / Paul Taylor

Hawke’s Bay Regional Council didn’t open a stopbank spillway near Waiohiki on the morning of Cyclone Gabrielle. But the spillway’s existence and the fact the digger was sent to potentially do the deed as the water rose, has become a flashpoint for flood-wary and flood-weary Pakowhai residents. James Pocock reports.

Mike and Sue Brown woke to a wet but relatively calm morning at their home in Pakowhai.

It felt as if the cyclone had gone.

Hours later, they would be rescued from the roof of their Pakowhai home after water rose five to six metres to engulf the community around them.

Pakowhai is near the confluence of the Heretaunga Plains’ two main rivers - the Tūtaekuri and the Ngaruroro.

The floodwaters on February 14 came from both sides.

Hawke’s Bay Regional Council says water flowing from three places on the right bank of the Tūtaekurī - Swamp Road (Moteo), Waiohiki (Omarunui), and near Brookfields Bridge - flowed into Pakowhai.

Then there were breaches from the left bank of the Ngaruroro, at Omahu and downstream of Fernhill Bridge, that also sent water Pakowhai’s way.

The quantities and timing of the breach events are being modelled by the council.

The council has repeatedly told residents that these breaches were natural rather than manmade - caused by the sheer volume of water on February 14 rather than by diggers or bombs.

Misinformation on the subject has run rampant on social media, frustrating the council.

THE DIGGER SENT TO THE SCENE

The only human intervention that the council has confirmed is that a digger was sent to Waiohiki between 6am and 7am on February 14.

This was done in case there was a need to create a spillway in the right bank of the Tūtaekuri.

The digger was not used, and a spillway was not opened. Even if it was opened, the flow would have been “small” and “controlled”, council says.

But that didn’t stop the furious response, to the revelation of the digger, at a Pakowhai community meeting recently. If things were bad enough to send a digger, why weren’t locals told to get out?

There are now questions about future flood protection, with residents concerned there is an option available to the council to spill river water onto the plains, that it might well use with more haste in the next flood.

While some property owners have already expressed their desire for a ‘red zone’ style managed retreat from Pakowhai, plenty, including the Browns, want to stay and rebuild.

The Browns say the sequence of events on that morning is also troubling.

At the time the digger was mobilised, communication for Pakowhai appears to have still been in working order, and the Browns say there should have been an immediate notification sent to everyone in the village.

“At that stage, they [authorities] should have definitely been telling people to get out of the area and they never, ever did,” Mike said.

Sue said that without an understanding of the seriousness of the situation, and what the council were considering to mitigate it, there was no urgency for residents in Pakowhai to leave.

“They left us to drown.”

Mike Brown and his partner Sue say there should have been a warning for Pakowhai residents when the council mobilised a digger to potentially open a spillway up further up the river. Photo / Paul Taylor

Chris Dolley, regional council group manager asset management, said the Hawke’s Bay Civil Defence Emergency Management (CDEM) Group would have taken action to notify residents, if a decision was made to dig out the section.

“Timing of events made it unlikely that a notification just to mobilise the excavator was possible,” Dolley said.

He said the decision on whether to dig out the spillway was put on hold, after updates from field crews when the digger arrived. No decision was ever made to dig out the spillway due to the “rapidly evolving situation”.

WHAT IS THE SPILLWAY?

A diagram from the 2021 Heretaunga Plains Flood Control Scheme Asset Management Plan showing a part of the Tūtaekuri River's stopbank built in a way that allows the council to release water during a flood. Graphic / Hawke's Bay Regional Council

Dolley said the spillway and specially constructed segment of the stop bank, located between the Redclyffe/Waiohiki Bridge and the SH50 Bridge on the outer stopbank of the Tūtaekurī River, was the only pre-planned location where a controlled release of floodwaters could occur.

“At this location, there is a specifically constructed segment of stopbank (constructed in the late 80s) with a cement stabilised portion below the crest,” Dolley said.

“A digger would remove the material down to the stabilised portion to allow some of the river flow to be diverted through a spillway. This is a small and controlled flow.”

He said the flow would go into the drainage network on the agricultural land adjacent to the spillway before eventually reaching the Pakowhai pump station.

“The actual flood extent would depend on the duration of the flood on the Tūtaekurī River.”

CIVIL DEFENCE STILL AWAITING POSSIBLE INQUIRY

The Browns said they were also disappointed HBCDEM group management had not attended two Pakowhai community meetings over the past few weeks, to answer questions about evacuation warnings and the response.

A HBCDEM spokesperson said its Group Controller receives notifications of community meetings, including the most recent Pakowhai community meeting.

“The current priority for HBCDEM staff still working on the response remains on ensuring our isolated communities and impacted persons get the emergency welfare support they need.

“An ongoing focus is also on monitoring the weather and ensuring we’ve still got a team in place ready to respond to new developments.”

The spokesperson said Civil Defence expected there would be reviews and inquiries undertaken into the period leading up to the event and the initial stages of the response.

“We would welcome any inquiry to ensure our emergency management system continues to learn, improve, and provide the best possible outcomes for our communities.

“As this was a national event with a national state of emergency, we are still awaiting the Government to outline its intent regarding an inquiry, our part in this, and how this would impact on any reviews we conduct.

“We can provide more detail once we have an update from central Government.”