The interconnected risks of flooding

This research was applied to give the government, flood risk management authorities and the insurance industry a better understanding of risk.

Transforming flood assessment at multiple scales through better statistical understanding of risk

1 JBA Trust and Lancaster Environment Centre, Lancaster University, United Kingdom

Research led by Lancaster University, JBA and the JBA Trust - conducted over a decade - has supported the government, flood management authorities and the insurance industry to have a better understanding of flood risk from local to national scales.

Historically, flood risk was often assessed in isolated terms. This meant the focus was on single locations or individual flood events, rather than accounting for how extreme weather patterns can co-occur across large areas. As a result, assessments could underestimate the broader, interconnected risks of flooding.

The research team addressed this gap by developing methods that model flood events as multivariate extremes. This allowed for a more realistic estimation of the likelihood of concurrent flooding across multiple locations. The approach enabled flood risk to be assessed at a national scale, informing decisions in the UK’s National Security Risk Assessment (NSRA) and aiding global reinsurance companies in risk evaluations.

The research breakthroughs were founded on multivariate extreme value theory. The theory addressed the probability of multiple extreme events occurring simultaneously. Prior to this research, methods were limited in scope, handling only a few variables or locations. While they were mathematically convenient, they didn’t align with real-world flood data, often leading to inaccurate risk estimates.