New Canterbury research hopes to save lives by predicting landslide dams

Landslide dams form when debris from a landslide blocks a river channel. This creates a large dam that backfills into the upstream valley and eventually bursts. This is known as ‘outburst flooding’, and can have devastating impacts on communities, destroying homes and infrastructure.

As witnessed in the Kaikoura event, large numbers of landslides and landslide dams can form after a significant earthquake. Heavy rainfall can also cause landslide dams and increase the risk of the dam bursting.

Jane McMecking, a master’s student in the Disaster Risk and Resilience Group at the University of Canterbury, has created a model to assess where landslide dams and outburst flooding might occur on the West Coast as part of her Master of Science thesis. She hopes her research will save lives in the event of an Alpine Fault earthquake and help councils and local Civil Defence with their evacuation plans.

Her thesis ‘Landslide Dam Hazard Modelling in the West Coast of New Zealand’, was funded through the Toka Tū Ake EQC University Research Programme, which invests in research and capability building to increase resilience in Aotearoa.

Landslide dams are likely to form along the mountainous regions of the West Coast during a large earthquake.

They are most hazardous when they are in areas near communities and lifelines, such as farming regions and State Highway 6. For example, a landslide dam outburst flood in the Haast catchment could impact State Highway 6 for tens of kilometres, while the farming communities in the Hokitika and Whataroa catchments were also identified as high hazard.

Although the prospect of a landslide dam outburst flood sounds daunting, McMecking says being prepared is key.

“The more science we have, the more we understand these hazards and the more we can work with communities and relevant organisations to understand the impacts of potential hazards and improve our resilience. Landslide dams aren’t well known, so I’m hoping this project will bring more awareness.,” says McMecking.

McMecking’s research was recently recognised in the Three Minute Thesis competition where university students summarised their work in a three-minute video without props or animations. The University of Canterbury student was awarded first place in the Masters category and represented the university in the national final in September 2022.

Toka Tū Ake EQC Head of Research Dr Natalie Balfour says that this kind of research is essential to understanding the impact of natural hazards on communities.

“We know that secondary events, like flooding after an earthquake, can cause more damage than the actual main event, so it’s important to identify which areas are most at risk,” says Balfour.

“We’re proud to fund this and other University Research Programmes, which are part of the $20 million that Toka Tū Ake EQC invests in natural hazard research every year to support local communities so that everyone can be better prepared. Applications for the next round of University Research grants are open and I’m excited to see more amazing work, which will help build resilience and protect people and property.”