Dr Murry Cave1, Bryce McLoughlan2, Nick Gordon2, Lenka Ondrackova2
1 Principal Scientist, Gisborne District Council
2 Gisborne District Council
Murry.cave@gdc.govt.nz
For the Gisborne/Tairawhiti region 2023 was a difficult year with 8 severe storms and several irritating ones while Cyclone Hale (January), Cyclone Gabrielle and Son of Gabrielle (February), June and then November having the most impacts. The storms caused severe flooding, landslides and the mobilisation of large woody debris. The impacts of Gabrielle were profound with 9 breaks to Gisborne’s water supply pipeline, multiple bridges lost, roads damaged and houses damaged or destroyed. Compounding the impacts were antecedent conditions with soils fully saturated after Cyclone Hale and with elevated watertables persisting into 2024.
The above-mentioned impacts were the focus of much of the media attention, but the impacts on the productive rural sector outside of forestry did not get the same attention but maize, and vegetable crops were destroyed and citrus, apple and kiwifruit orchards badly damaged.
The Crown via the CRI’s and other government agencies such as MPI and MfE all initiated science responses as did Gisborne District Council itself. Three years on it is useful to reflect on that science response, how effective was it, did it deliver and was it well targeted at the real needs of the community and the economy. Equally the science response was just that; it focussed on the short-term immediate response and not on the long-term recovery for the impacted regions.
If we don’t consider those things that went well, those that didn’t go well or those that petered out without reaching a conclusion, we will not learn from the experience. That implicitly means we will likely repeat the same mistakes the next big event.
- Gisborne District Council had its own science actions leading up to the storm events, during the immediate response phase and also during the long tail of recovery. These actions included;
- Identifying the threat and mobilising for response well before the first watch issued by MetService,
- Acquiring key data particularly aerial imagery, flood heights etc as soon as practicable post event,
- Connecting in with key science funders and providers post event in an attempt to steer the science response towards what was needed in the community, not that which was interesting to the researchers,
- Supporting the collection of perishable data such as soil samples for the research providers,
- Telling the story of the storms of 2023 via conferences and workshops in Gisborne, presenting papers in other fora, submitting on the many various reviews and regulatory changes post 2023, including reviews of the science response itself, and in too many cases,
- Picking up the tab or undertaking the work to complete science projects that were not completed.
From our analysis of the science response, it can be concluded that the overall Central Government-funded research supporting the North Island Weather Events was well intentioned. But it lacked focus and did not carefully consider whether or not the research undertaken would provide meaningful benefits to the communities impacted by the storms. Not all response research fell into this category, however, and it is telling that research that were community led (albeit having the Regional Councils as a proxy for the community) or were industry led (but often funded by MPI) were more focussed on community or economic outcomes and were able to deliver the required outputs. Two projects stand out;
- Cyclone Gabrielle Baseline Sampling 2023 which delivered in September 2023 and focussed on soils (MPI supported by Vegetables NZ), and
- Cyclone impacts on fisheries (MPI-Fisheries).
But there remain big gaps and one that particularly comes to mind is an overarching detailed technical analysis of the event that looks at how the storm developed, and the across region impacts.
- What were the total and daily rainfalls and where did those rains fall?
- What was the maximum flood spread, how many landslides were there and what was the relationship between land use and landslides?
- How did the soils change as a result of those silt inputs. What land use changes are required to make the regions more resilient?
And possibly, the elephant in the room question that no one wants to address is whether or not our people are living in places that can be made safe from future severe weather events like those that occurred in 2023.