2023 Year in Review

Read NIWA's 2023 Year in Review.

The NIWA 2023 Year in Review is available to download as a PDF document (PDF 7MB) and a digital Issuu publication:

Chairman and Chief Executive Review

"We must brace ourselves for more frequent and intense storms in the years ahead".

We wrote that opening message only 12 months ago, for NIWA's last Year in Review. At the time, we were reflecting on 2022's West Coast deluge, when hundreds of people were evacuated to escape record river flows.

But we were not expecting the benchmarks for extreme weather to be reset so quickly. As Aucklanders geared up to celebrate their anniversary holiday weekend, the heavens opened. On Friday 27 January, catastrophic flash flooding swept across the city.

Our meteorologists reported that an entire summer's worth of rain fell in one day. Four people lost their lives. It was the worst flood that Auckland had experienced in living memory.

As Auckland's clean-up began and the nation reflected, more trouble was already brewing in the north Pacific. NIWA's Forecasting Services team watched in alarm as Cyclone Gabrielle began to form in the northeastern Coral Sea.

Worried by its size, the team alerted agencies to Gabrielle's progress. A string of briefings followed for Fire and Emergency New Zealand, the Department of Conservation and the Ministry for Primary Industries, with officials from the National Emergency Management Agency and local authorities also sitting in. These briefings were interspersed with ongoing media interviews and updates on social media. With the cyclone's track still uncertain, our coastal science and river flow specialists added their expertise. Our natural hazards scientists combined coastal storm surge predictions with forecasts for all the possible cyclone tracks. Another group of experts focused on river catchments – pinpointing the areas most likely to be impacted by high river flows by using a new modelling tool that combines rainfall forecasts with a hydrological model.

Other scientists looked at landslide risks. Over the past year NIWA has been working with GNS Science on a pilot study to predict rainfall-induced landslides in Wellington – combining NIWA's near real-time rain forecasts with GNS's land stability data.

As Cyclone Gabrielle approached, GNS trialled the tool across much of the upper North Island to create impact forecasts for houses, roads and rail networks. These were shared with councils, central government and emergency response agencies to inform decisions about evacuations and road closures.

The cyclone hit on Sunday 12 February. An estimated 225,000 homes lost power, sediment buried houses to their rooftops and roads were destroyed. More than 10,000 people were displaced, and the entire city of Napier was cut off for weeks. Sadly, Cyclone Gabrielle claimed 11 lives and became the costliest tropical cyclone on record in the Southern Hemisphere, with total damages estimated at more than NZ$13.5 billion.

But having the science expertise on hand was invaluable, and the toll could have been much worse without it. In the lead up to and during such extreme weather events, weather forecasters need to be tied to scientists who understand the downstream impacts – meteorologists working alongside hydrologists and coastal scientists, for example, so they can provide advice about likely river flooding and coastal inundation. In the days that followed, NIWA's river flow experts and hazard scientists rushed to Hawke's Bay to capture vital data. Their mission was to measure and map the flood levels and extent to calibrate our flood models and help pinpoint the mechanisms driving sediment transport and stopbank breaches.

That will be key to designing new flood defences, future-proofing property and infrastructure and helping New Zealand recover from similar events.

Read the complete review in the NIWA 2023 Year in Review [PDF 10MB]

2023 Annual Report

View and download NIWA's 2023 Annual Report.