The 250-page independent review of its Cyclone Gabrielle flood management, rich in detail, graphics and photographic documentation, was released by the HB Regional Council on Wednesday.
On all accounts, an excellent contribution to understanding what happened in terms of flooding during the cyclone, how HBRC responded (not Civil Defence or our territorial authorities), and lessons for moving forward. The review was undertaken by planning expert Dr Phil Mitchell Chair, water management expert Kyle Christensen and Māori barrister Bernadette Roka Arapere.
The panel clearly waded deeply into the community and HBRC to understand what transpired.
As various councillors commented, this report offers enduring value to HBRC as its analysis and 47 recommendations become the accountability standard against which to measure the sufficiency of HBRC’s future remedial actions.
Key takeaways …
Infrastructure planning & solutions
We’re slow learners … and not just the HBRC. It was pointed out that HB’s historical floods, most notably the 1938 floods, which was bigger than Gabrielle’s, offered information and warnings not incorporated into current planning, including where to not build.
As other reviews of the disaster have noted, the scale of this 1-in-1000 year event – not one river, one location, but all of HB with intensity surpassing expectations and rainfall predictions by NIWA – was simply overwhelming to those attempting to respond with outmoded legacy systems and processes.
The panel delivered a critical dose of reality to our entire community. We should not expect perfect safety in the future from stopbank protections.
Stopbanks can offer a certain degree of protection, and get us by in many situations, but in such severe events they will not suffice. And so the challenge becomes managing the flood overflow as safely as possible – from the upper reaches that will first be breached down through flood plains to the sea.
This new approach must be imagined and designed with all community stakeholders, as it involves decisions about pathways, property rights, risk allocation and priorities.
“The key strategic arrangement of the catchment system needs to be based around the evolving global best practice of ‘Making Room for the River’ and ‘Natural/Nature Based Solutions’, with the overarching objective to safely convey very large floods from the upstream end of the floodplains to the sea,” wrote the reviewers.
The expectation of future ‘Super design’ events demands a higher order of advance planning by HBRC and other stakeholders. In a Gabrielle-scale event, where will the structural defences fail, where can that water be expected to go, and how can we best direct it?
“The lack of planning and preparedness for events exceeding the capacity of stopbank systems was also apparent in the many unprotected floodplains of the region. 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,” said the reviewers.
In fact, without this planning, no one could have known where Gabrielle flooding would actually occur, leaving the potential evacuation of 100,000 Heretaunga residents – if the breaches had occurred elsewhere, flooding urban Hastings or Napier – an impossibility. As reviewer Kyle Christensen put it in his presentation, that Taradale and Napier were not flooded was a matter of luck.
So, yes, we need a plan for a 1-in-1000 year event! Who would even have dreamed about that before February 2023?
Policy direction
Another key set of recommendations focused on what reviewers termed the “advocacy’ role of HBRC. To put it more bluntly than the reviewers did, HBRC must be enabled by its Regional Policy Statement and prepared to instruct territorial authorities where not to build. The review cited examples where developments have occurred either because HBRC wasn’t afforded the opportunity to object … or was ignored when it did.
Said reviewer Dr Phil Mitchell:
“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.
“Residential developments have been allowed to occur in locations such as the Esk Valley and Tangoio despite a well-documented history of significant flooding. Such areas are considered unsafe for residential use and are now within the Category 3 classification. Similar declarations were made by local authorities following the 1938 Esk Valley Flood and the 1963 Tangoio Flood.
“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.”
Of course HB’s mayors put out a joint media release welcoming the report … but no comment on this matter.
It will be interesting to see how this plays out as HBRC, HDC and NCC work out their pending ‘Napier Hastings Future Development Strategy’.
Mana whenua
A critical set of findings from the review concerns mana whenua. “The panel considers that mana whenua were disproportionately impacted by the flood,” says reviewer Bernadette Roka Arapere. The typical pattern observed was that land currently occupied by Māori communities is the remnant of much larger holdings they held prior to pākehā occupation.
“In many places there was known flood risk at these floodplain locations, and no structural flood defences or planning to provide management of that flood risk,” she commented. “We received feedback of a disconnect between some mana whenua groups and HBRC, and a perception that HBRC does not protect mana whenua communities in the same way that other communities are protected against flood risk.”
The panel said inequities around the level of protection provided between mana whenua and other Hawke’s Bay communities must be acknowledged and addressed in any future flood management model.
Funding
Finally, the biggest elephant in the room … who pays for the more effective flood protection required?
The review is clear: “The cost of rebuilding and improving flood management infrastructure is likely to be unaffordable if solely funded by local communities. A shift back to central government partially funding these works is likely to be needed to achieve effective long term solutions.”
Nothing more can really be said about that. It’s up to the Government to respond. It’s much easier to appear to be ‘helpful’ by appointing Crown Managers to expedite progress, as will be done in the case of HBRC/Wairoa planning. But at the end of the day, hard cash – and heaps of it – will be required.
But this is a much bigger issue for the Crown than recovery from one cyclone and more flood protection for Wairoa, the Heretaunga Plains or Waipawa. It’s about funding resilient NZ infrastructure of all kinds for the 21stCentury. That cannot be done by today’s ratepayers and taxpayers. Our collective wallet is puny compared to the requirements. Much more significant debt financing and private investment (including overseas) will need to be in the mix.
And it’s also a bigger issue for HB’s five teeth-gnashing but redundant councils, who impose huge transaction costs on our community, including bureaucratic delays, with their ever more numerous patchwork attempts to deal at glacial pace with one after another monumental regional issue – flood protection, coastal hazard protection, regional housing and economic development, water security, civil defence and more.
You can read the Panel’s media statement and full report here.
It’s interesting, but unless I have missed it in the report there is absolutely no mention of the fact that by stripping the land of trees on the hills in the catchment areas we have greatly increased runoff and the speed at which it enters the rivers. The stop banks are the ambulances at the bottom of the cliff really. We could reduce our reliance on them if we gave landowners the right incentives to reforest. It would also increase carbon sequestration at the same time in a win-win situation. But that would take long term thinking and proper debate between rural landowners and the urban population at risk of flooding…
Glen, this is exactly the work the catchment team at HBRC are doing and the point of the HBRC ‘Land for Life’ programme. Couldn’t agree with you more.
Thanks for that Sophie. That is good news. It is still odd that the panel report didn’t mention this sort of work in their recommendations though (unless i missed it?).
https://www.hbrc.govt.nz/environment/farmers-hub/land-for-life/
Glen, I agree but find river management is lacking since the days of the HB Catchment Board. This comprehensive report could have been one of the last if HBRC had included an on-site assessment of pine forest harvesting and the significant contribution to local flooding. Just like serious HB coastal erosion since 1976 – the Council has failed to establish ‘the cause’ which means durable solutions have a long way to go. This assessment needed to include rejected logs, machine-stripped branches, and dislodged vegetation from harvesting and how this material reached the streams, the rivers, the bridges, developed areas and eventually the sea. Somehow, the 250-page ‘Review’ does not mention forest harvesting debris or ‘slash’ and only refers to logs once (p. 215 where it notes logs blocked the Esk River mouth). This introduced waste product was a major contributor to damming rivers and collapsing bridges because floodwater (with or without silt) has not, and will not, destroy sound concrete bridges. The sudden release of this huge volume of floodwater with rapids loaded with timber debris had breached downstream stopbanks. This accounted for the severe flooding to residential and industrial areas plus vital infrastructure. When the HBRC analyse the readings transmitted from water level gauges at bridges on the main rivers (until they collapsed), the cause and solutions should become obvious. The outcome could suggest it’s too soon to blame the extent of damage on Climate Change.
Larry,
Again, there’s no doubt or confusion on the part of HBRC or anyone else about the need to keep both water and soil in place in the upper reaches of these catchments through more prudent land use and forestry practices. That work is underway and of course requires cooperating property owners.
The remit of this review was to examine HBRC’s response to the actual weather event. And on that the panel did a thorough, instructive job IMHO.
But key to everyone’s understanding is that, notwithstanding better land protection practices upstream, NO stop bank system will provide perfect safety from breaches in future weather events of the scale of Gabrielle — or as likely, worse.
Tom Belford
Good to have this information in the public arena. One issue not mentioned when commenting on territorial authorities allowing development in high risk areas is that some of them have capitulated to new housing expansion in high-risk areas after property developers have threatened litigation if consents to build are denied. This can require councils to reluctantly spend rate-payers money to defend against such developments (Te Awa in Ahuriri springs to mind) or back-down – which then allows developers to proceed largely unchallenged.
I think most commentary loses sight of the fact that the water wasn’t the core problem. The issue was the debris along the river ways, which built up on the bridges, impeding the flow of the water & causing river levels to rise more than they should have. Also, here & in Wairoa, outlets to the sea were also probably poorly designed & maintained. Obviously bridge design is another issue we’ll get a chance to address. Water can be quite cooperative if it’s given an easy path to follow.
The problem is though Paul, if you speed the water up more erosion will occur. What we need to be doing is slowing it down, ideally close to source. And while debris was obviously not great for the bridges the sheer volume of water certainly was the core of the problem. If we slow the water down it will reduce the volume in the rivers and then the debris wouldn’t be a problem either.
To both Paul and Glen
HBRC is well aware of the fundamental of holding water and soil in place in the upper catchments — major soil erosion programme has been underway for some time, but needs intensification. Moreover, the soil/silt carried away in floodwaters massively increases the destructive force of the floodwaters.
Do we take it on trust that HBRC and landowners have a good handle on the problem, then? HB Forestry Group chairman Keith Dolman certainly thought so when he welcomed, after Gabrielle, the council commissioned Report Into Pine Industry Debris, calling it ‘positive’ for the industry. The report could only categorically say that 9% (on average) of the debris was ‘cut pine’, and therefore from forestry harvesting – but actually 80- 90% of the debris was potentially from the same activity, it just didn’t have chainsaw marks. Another unfortunate aspect of this report was that key Northern HB sites (Wairoa river mouth, Opoiti bridge, Waikare River) were only assessed from the air and did not feed into quantitative data. The conclusion that HB flooding was different to that reported in the Tairawhiti report, was flawed – if Northern HB data was collected and reviewed separately, IMHO it would have shown strong similarities with Tairawhiti; pine industry debris was clearly implicated, and a comparison with Bola flooding, after which pines were promoted as a solution in Nth HB and Tairawhiti, is valid. Debris was not a factor then but is likely the cause of the surges which flooded North Clyde in Gabrielle. Note also that the Wairoa bar was not a problem in Gabrielle, with the recently flooded areas not affected. So, is it about rivers? I agree with Larry Dallimore, that, at least in the Wairoa area, the spotlight especially needs to be on landuse.
Tom, The latest idea to ‘retain both water and soil in the upper reaches of these catchments during major flood events’ appears to be inappropriate and entirely unsuitable for HB high country. Where gradients allow any form of water storage, the streams and rivers are wide enough to handle floodwater volumes similar to those created by Cyclone Gabrielle. It is the introduced material that alters the depth between the riverbed level and the height of stopbanks or in the upper reaches where stopbanks are deemed unnecessary and where flood risk does not exist.
I witnessed the Feb23 flood between the Puketapu Bridge, which collapsed at 4 am, and the Redcliffe Bridge, which collapsed at 11 am. I watched the preventable destruction of homes, orchards, livestock, and more get destroyed by the massive release of floodwater that breached perfectly sound stopbanks on either side of the river. The floodwater completely inundated many homes and sheds filled with precious gear and many other properties downstream that were flooded to roof levels.
During the afternoon after the Redcliffe Bridge collapsed, the needless devastation became apparent. Those homeless were taken in, live animals were moved to higher ground, and we did our best setting up and sharing power generators. Rather than the latest bright idea to hold vast volumes of floodwater in higher regions for controlled release, the HBRC should simply ensure flood water reaches the coast without impediments. Also, the HBRC should remove all culverts in catchments exposed to forestry debris because rather breach during floods, they tend to transfer the trapped floodwater to the next weakest point and possibly away from established drainage.
I also disagree with your assertion that “NO stop bank system will provide safety from breaches in weather events similar to Gabrielle or worse.” According to HBRC river flow gauges at HB bridges, it was not the stop bank system or extreme flood flows passing under or over bridges that caused the breaches and collapsed bridges. It was the accumulation of timber debris (many pine logs) that built up and blocked river flows at bridges. The built-up pressure and extreme force of this floodwater, loaded with debris, against these blockages, were obvious reasons for collapsed bridges, IMHO.
Larry, I fully agree with you comments about debris impact. I fully disagree with your comment about water retention. For example, take a look at this article, near the end: https://www.hbfuturefarming.org/news/article/215/transformational-change-at-tunanui-station
And I disagree also with your confidence in the future viability of what — skyscraper flood banks? — in the face of expected ‘super design’ weather events.
Tom Belford
Tom, I wish we could discuss these issues more thoroughly so we can clearly understand what we support and disagree with. My position remains the same – I agree with retaining rainfall for farming, but I oppose temporary storage on these braided rivers because floodwater needs a clear passage to the river outlet. For the HB coast, the gravel and sand created and transported by our rivers is vital replenishment for our beaches which protect a huge area of developed land. Retaining rainfall upstream of dammed bridges until timber debris is cleared has been suggested by others, not me. We need to keep the rivers and riverbeds wide enough between stop banks, which must also be deep enough to ensure they don’t breach. Your understanding that I support ‘skyscraper flood banks’ is nonsense. I support maintaining and improving stopbanks to ensure they can handle extreme and predicted rainfall events. Additionally, I advocate for improved river management that ensures logs, branches, and debris from forest harvesting do not enter our local river systems. Let’s agree to disagree on HB rivers and the HB coast and touch base when an event removes all doubt. Love to know what odds you’re offering.