PhD student:
Clevon Ash (GRI – UoC)
Supervisors:
Matthew Wilson (GRI – UoC)
Iain White (UoW)
Carolynne Hultquist (SEE – UoC)
Funding:
MBIE Endeavour Research Programme – Increasing flood resilience across Aotearoa, New Zealand.
Duration of Project
2023-2026
Summary:
Like many other countries around the world, New Zealand experienced numerous floods between 2022 and 2023. In 2022 Aotearoa experienced over 600 million dollars in losses, however, in 2023 this figure skyrocketed to over 3.5 billion dollars with the passage of Cyclone Gabrielle and the Auckland Anniversary weekend floods. According to the National Institute for Water and Atmospheric Research (NIWA) who uses complex flood models to predict how flooding is going to change over the next few decades, these figures are likely to increase based on climate projections. The aim of this research is to develop a better understanding of uncertainty representation in flood risk management and to determine the impact that it has on decision making. As the uncertainty associated with flood risk grows due to climate change and other factors it becomes imperative that decision makers can make the decisions needed within acceptable margins of error to protect the people of Aotearoa and its assets. To achieve this aim, the following research questions were defined:
I. How are different types of uncertainty represented in aspects of flood hazard risk assessments?
II. How do different uncertainty representations influence decision making for planning purposes?
III. What are the options for improving the treatment of uncertainty in flood hazard risk assessments?
It is hoped that the outcomes from this research will help to improve our understanding of uncertainty representations for flood hazards and how it can be used to make better decisions to reduce the impact of climate change for future generations.
2025 Research Update:
Using the results of the Monte Carlo Method (MCM) modelling, an ensemble of flood model outputs was used to create uncertainty visuals using flood criteria such as extent, depth and confidence that were then tested with risk management practitioners from across regional/ district councils, central government and private sector agencies in New Zealand. This feedback was then incorporated feedback into a series of recommendations and used to design a novel map interface that was used to further test perceptions of flood uncertainty and its link to decision-making. At the final Endeavour Flood Project Roadshow this novel interface was used in a pilot test along with the GRI’s Digital Twin Map interface.
Outputs:
Ash, C. Using RiskScape to measure the Impact of Flood Uncertainty on Decision-Making. The Fourth Spatial Data Science Symposium. UoC, Christchurch, September 5, 2023. Poster.
Ash C., Wilson M., White I., Hultquist C. Serious games and decision-making with flood risk uncertainty in Aotearoa-NZ. Waterways 2025 Postgraduate Student Conference. Christchurch. November 12, 2025.
Ash C., Wilson M., White I., Hultquist C. Implications of uncertainty in flood hazard assessments for planning under climate change. Endeavour Roadshow 8. Hamilton NZ. October 29-30, 2025.
Ash C., Booker K. Ivory V., Reducing the uncertainty when we talk about uncertainty: Understanding and communicating uncertainty at the science-policy interface. Society for Risk Analysis Conference, Melbourne, Australia. February 6-7, 2025.
Ash C., Wilson M. White I., Hultquist C., Nguyen M. A Monte Carlo Approach to Representing Flood Risk Uncertainty for Decision-Making. Society for Risk Analysis Conference, Melbourne, Australia. February 6-7, 2025.
