“The whole point of flash floods is the flash part”: A mental model approach to improving flash flood communication and decision making

The fast onset of flash flooding means that effective communication and decision making is critical to save lives and reduce other negative impacts when a flash flood threatens. A mental model approach to improving risk communication involves examining public perceptions of the causes, consequences, and responses to risks in order to target areas of confusion and erroneous beliefs. As part of a larger project to understand and enhance warning decisions in extreme weather events, we explored how members of the public in Boulder, CO perceive flash flood risks, warnings, and response decisions. Although the City of Boulder has not experienced significant flooding in decades, its geography (including recently burned terrain) and meteorology place it at high risk for flash flooding, and there have been devastating flash floods in nearby communities. Data from 26 interviews with members of the public are used to 1) examine mental models of flash flood risk, warnings, and response and 2) identify similarities and differences between public perceptions and expert understandings (based on analysis of separate interviews with NWS forecasters, television and radio broadcasters, and public officials). Analysis of the public interview data indicates that most members of the public interviewed are aware of the general threat, but they demonstrate a range of understanding about the causes and consequences of flash floods. Areas of interviewees' confusion and divergence from expert models – such as when flash floods are more likely to occur and the time available for response - indicate starting points for improving flash flood risk communication which may take the form of event-specific warnings or longer-term education.