Flash flood knowledge and uncertainty communication in warnings: an Australian study

Knowledge of the hazards, protective actions and the language used in warning messages is essential for safety and informed decision-making particularly during flash flooding and hazardous weather events.

Equally important for effective risk communication is knowledge of what recipients already know and the inclusion of context and uncertainty information in forecasts and warnings.

There is limited empirical research about how people interpret warnings based on their levels of knowledge and past experiences. A survey of 1,235 people was conducted to understand people’s knowledge of the causes of flash flood, the risks, effects, protective actions and definitions as well as interpretations of terms of likelihood used in rainfall warnings.

Survey results showed that the hypothesis that emergency management practitioners had more knowledge of flash flood than the public was only partially supported.

Results showed gaps in understanding, in particular, the verbal probabilistic terms of 'likely' and 'possible' that are used in rainfall warnings were interpreted inconsistently. This presents a challenge when communicating uncertainty.

This study shows the need to improve the communication of uncertainty in forecasts and warnings and advises the use of defined numerical probabilities with verbal terms.