WELLINGTON, Aug 20 (NNN-RNZ) – New Zealand’s Cyclone Gabrielle in 2023, has been confirmed as one of the most extreme landslide events ever recorded globally, research revealed yesterday.
Cyclone Gabrielle triggered over 800,000 landslides, covering 100 square kilometres, in New Zealand’s North Island, according to an analysis released by Earth Sciences New Zealand (ESNZ).
The analysis, published in Landslides Journal, found that, the sheer intensity of rainfall during the Feb, 2023, cyclone, made widespread slope failures inevitable.
In some locations, such as inland from Esk Valley in New Zealand’s Hawke’s Bay, rainfall reached 500 mm in just 24 hours, 50 percent above the previous record, said co-author Trevor Carey-Smith, ESNZ climate scientist.
“The intense rainfall over a short period, overwhelmed the natural drainage systems, and many of the affected slopes were inevitably pushed past their tipping point, regardless of the pre-existing soil moisture conditions,” said lead author, Chris Massey, ESNZ engineering geologist.
Carey-Smith, who analysed the rainfall data, noted that, the volume of water fell at rates far beyond historical precedents and that climate change had increased the event’s intensity.
The study found, landslide risk depended on rainfall, slope steepness, geology, and vegetation, with scrub and grassland areas showing record-high densities – up to 327 landslides per square kilometre – while indigenous forests offered better protection than exotic ones.
It linked recent deforestation to increased landslides and emphasised the need for resilient land-use planning, highlighting the findings’ importance for disaster preparedness, amid climate-driven cyclone intensification.– NNN-RNZ
