Surface water flood warnings requirements and potential in England and Wales

This paper examines the potential for developing surface water flood warnings in England and Wales by focusing upon the requirements of professional and public flood warning responders. The recent development of Extreme Rainfall Alerts (ERAs) presents an opportunity to develop such warnings. However, uncertainties concerning event probability, the location and likely impact of floods would significantly complicate the risk communication and warning response process limiting warning effectiveness. Feedback, interviews and workshops involving professional emergency responders and public focus groups allow the reception to existing ERAs and to proposed linked flood warnings to be gauged. For professional responders ERAs are useful and the majority take preparatory actions on receipt of them. There is support for surface water flood warnings among professional responders, particularly if uncertainties can be reduced and warnings tailored to their requirements. Higher quality linkages are required between rainfall intensity and duration and flooding and between forecasters, warners and the warned. Most flood experienced members of the public want surface water flood warnings but scepticism exists about ability to effectively provide them. Reasons include inherent forecasting uncertainties and lack of confidence in the responsible authorities. Existing constraints on developing warnings include reliability issues surrounding flood warnings, the current level of understanding of probabilities and low levels of public flood risk awareness.

► Significant potential exists for developing SWF warnings based on ERAs.
► Most PERs require a more tailored and specific warning than the alerts currently provided.
► Rainfall-based alerts utilising locally specific rainfall and runoff thresholds are preferred.
► Targeted SWF warnings for the public are likely to be premature in the short-term.
► Members of the public desire more certainty, and trust and confidence in authorities.