Central OC Times

Researchers from the University of California, Irvine and the University of Bristol have called for a shift in how flood risks are modeled. In a commentary published in the journal Earth’s Future, they recommend moving away from "bathtub modeling," which simplifies flood hazards by assuming floods spread evenly over areas like a level pool. This method is often used for coastal areas but may not accurately reflect real-world conditions.

Brett Sanders, UC Irvine Chancellor’s Professor of civil & environmental engineering, explained that "bathtub models can both overpredict and underpredict flooding." He noted that these models fail to account for protective systems such as storm drains and levees.

Oliver Wing, chief scientific officer at Fathom and an honorary research fellow at the University of Bristol, highlighted the limitations of bathtub modeling using the critical success index (CSI). He stated that “CSIs under 0.5 indicate that these models are worse than a random classification.”

The researchers argue that studies using bathtub modeling often gain media attention despite acknowledged biases. Paul Bates from the University of Bristol emphasized the importance of accurate flood maps for various stakeholders, saying, “We all have a role to play in reducing flood losses, but it all starts with trustworthy information.”

The team suggests dynamical modeling as an alternative, which uses physics-based equations to provide more precise predictions. They stress that reliable models are crucial for effective community engagement and adaptation strategies.

Sanders pointed out that projections must resonate with people's experiences to be trusted: “Projections of flooding need to make sense to people...for deciding upon the investments and policies that will be made to manage it.”

This research was supported by several organizations including the U.S. National Science Foundation and the Natural Environment Research Council in the U.K.