Cyclone Gabrielle: Review finds major failings in Hawke's Bay Regional Council response

A scathing review of the Hawke's Bay Regional Council's flood protections during Cyclone Gabrielle has found major failings in its ability to plan, and respond to extreme weather events.

Flooding ruined hundreds of homes in the region last February, killed eight people and resulted in the red zoning of several communities because the risk to life was deemed too high.

Over the past year, the Hawke's Bay Independent Flood Review panel of Phil Mitchell (Chair), Kyle Christensen and Bernadette Roka Arapere, has been investigating the circumstances and contributing factors that led to the widespread flooding.

The 260-page report was presented to the Hawke's Bay Regional Council (HBRC) on Wednesday, highlighting serious concerns around the lack of planning and preparedness for floods that exceeded stopbanks, which was evident in the region's many unprotected floodplains.

"Flood risk had been underestimated in a number of locations because large historic floods had not been included in the analysis of flood size, and there was limited detail or wider understanding of trigger levels and likely areas of inundation for warnings and evacuations to be effective.

"There was residual risk to the entire Heretaunga floodplain, including the densely populated urban areas of Taradale, Hastings and Napier. It meant that more than 100,000 people were at risk, owing to there being no practical solution for evacuations prior to a flood arriving," the panel said.

Two other inquiries made similar findings: a national inquiry led by former Governor-General Sir Jerry Mateparae and an investigation into the Hawke's Bay's Civil Defence response to Cyclone Gabrielle.

Flood hazard mapping

One of the most critical activities that the HBRC is responsible for is flood forecasting and advising Civil Defence so they can warn communities and evacuate people when needed.

To do this, the council uses its own flood hazard mapping and real-time river level monitoring systems, such as telemetry devices on rivers, and Metservice rainfall forecasts.

But the panel found many issues with this - such as a significant difference between forecast and actual rainfall, the failure of the repeater supporting some of the telemetry system, the loss of, and damage to, some water level and rainfall measuring equipment, and staff being overwhelmed by the sheer scale of the event meant.

"Genuine collaboration and partnership is needed between local and central government and communities, mana whenua and businesses to evaluate and progress options for better managing flood risk in the future," the panel said.

The panel made 47 recommendations for the HBRC across seven key areas, including better stopbanks, more detailed flood hazard mapping, stricter housing development rules in flood risk areas, more community collaboration and greater government funding.

Flooding infrastructure and weather event management

The review found legacy flood management infrastructure developed through the past century is, in many places, no longer fit for purpose. The recommendations called for a substantial upgrade and a re-imagined system that also made more room for the rivers when they flooded.

"Any new stopbanks need to be designed in a way that provides predictable and manageable performance during events that exceed their capacity," panel member Kyle Christensen said.

It would be a big shift from current designs, and fundamental to its success would be the modelling for 'super events' so stop banks performance in big floods is known and not left to chance. For example, knowing where spillways, overflows and known failure points are.

"The fact that there was no event management plan for the Heretaunga Plains was a result of there being no way of predicting where overflows would go, and no practical way of evacuating all of the 100,000 people possibly affected from the entire area," he said.

In areas with no stopbanks, but a known flood risk - such as Esk Valley, Tangoio, North Clyde and Porangahau - there was limited planning in place and the flood frequency analysis and flood risk mapping didn't include the significant historic floods in the Esk and Pōrangahau floodplains.

Advice through the event appeared ad hoc with a lack of clarity on what was actually being predicted, he said.

Planning control recommendations

Panel chair Phil Mitchell said the Regional Policy Statement which is the HBRC's main tool for influencing land use did not provide definitive direction to territorial authorities on how their district plans should identify and manage flood hazard risks.

"The fact that there were relatively new housing developments in areas of known flood risk suggests that lessons from the past have not been learnt, and development has been allowed in high hazard areas."

He said residential developments have been allowed to occur in locations such as the Esk Valley and Tangoio despite a well-documented history of significant flooding. Those areas are now in Category 3, as the risk to life was deemed intolerable.

"Weak and insufficient planning direction has enabled poor planning decisions, and shows just how short society's memory is when it comes to matters of flood hazard management," he said.

The review found large parts of the Regional Policy Statement had not been reviewed since 2006, and that key policies for flood hazard management are weak and too vague, leaving wide-ranging discretion for land use management in the various district plans. Mitchell said HBRC should urgently review the Regional Policy Statement.

Communities, mana whenua and resourcing

The 47 recommendations also include re-surveying all the river and stream channels to ensure gravel build up is managed properly, better protection of mana whenua, and more consultation with local communities.

"HBRC should recognise and provide for Māori communities and lower socio economic areas that are disproportionately exposed to flood risk, because flood protection of those areas does not satisfy HBRC traditional cost/ benefit approaches.

"The panel considers that more needs to be done to work with mana whenua at a governance level; that inequities between mana whenua and other Hawke's Bay communities need to be acknowledged by HBRC, and a new flood management model needs to be developed with mana whenua for a safe and sustainable future," said Bernadette Roka Arapere.

The panel heard about the HBRC's work with communities in relation to flood management, planning and recovery.

"One persistent theme was the lack of meaningful engagement and that local knowledge and perspectives were not seen by HBRC as being useful.

"It is essential that HBRC treats the region's communities as project partners, rather than consulting and seeking feedback once much of the scoping and critical thinking has already occurred. Community and stakeholder participation is fundamental to managing flood risk," the panel said.

It found the funding of river management, mostly derived from targeted local rates, to be inadequate in many areas. More central government funding is needed, along with a larger regional contribution.

Regional council responds

Regional council chair Hinewai Ormsby said receiving the report was an emotional moment for the council, and agreed the current funding model would not be sufficient to fund long-term solutions.

"This is a significant issue for smaller rural communities, and especially Māori communities where the value of land that has been marginalised over decades is considered insufficient to cover the cost of its protection," she said.

"As Hawke's Bay and indeed New Zealand works out how to deal with the effects of climate change and more intense storms, learning from our recent experiences is critical.

"What all the reviews have told us is that the way we have worked for the past 30 years can't be the way we work for the next 30 years. That journey has already begun and there is a massive amount of work ahead," Ormsby said.

The HBRC said it's already in the design phase for the Category 2 projects, to ensure there is no risk to life, and is upgrading pump stations and managing gravel in the major rivers.

"We are also assessing further upgrades to the flood mitigation network. We are increasing work to reduce hill country erosion and we have begun writing the next Regional Policy Statement. We have upgraded our telemetry system to make it more resilient," she said.