Last month I attended the 10th annual partners meeting of the European Flood Awareness System, of which the forecasting service is a member. EFAS provides forecasts across Europe, using a gridded LISFLOOD model fed by deterministic and probabilistic rainfall forecasts from ECMWF. Alerts for potential flooding are sent to the associated partners.
The meeting took place over two days in the European Commission’s Emergency Response Coordination Centre in Brussels, with around 50 practitioners present.
The first session featured talks by those responsible for general emergency response in Europe, such the Copernicus satellite mapping system, Civil Protection, the Floods Directive and the EU Solidarity Fund, and provided a useful reminder of how EFAS is used centrally, in addition to its use by the partner forecasting services.
The second section looked to the future, and emphasised the risks we face from climate change, with the likelihood of more frequent extreme events. This is however being accompanied by increases in weather forecasting skill, around two days per decade in the ECMWF model.
EFAS processes and procedures were then covered in detail during the updates from the operational centres (Dissemination, Forecasting and Data Collection).
The first day concluded with some presentations to illustrate the Balkan floods of May 2014, in which more than 60 people died and hundreds of thousands were evacuated, looking at the event from first a high level view, down to a regional and then local view. It was clear that the EFAS forecasts helped greatly with the emergency planning for this event, at a European as well as the local level.
The second day commenced with a detailed overview of service updates and changes, which were agreed by those present. These included an updated flash flooding indicator, European Runoff Index based on Climatology (ERIC), and changes to the alerting process, meaning that notifications will be sent for catchments of less than 2000km2. These changes will greatly benefit us in Scotland, where our catchments are relatively small and can’t match the current criterion of 4000km2. The possible future incorporation of the European Hydrological Prediction for the Environment (EHYPE) model developed by SMHI into EFAS was also discussed.
The final session was about probabilities. We are all in agreement that probabilistic forecasting through ensembles is the way forward, however it is not always appreciated that without appropriate communication to the informed recipient of the forecast we will always struggle to realise the potential benefits of this approach. The ‘Peak Box’ game illustrated how difficult it can be to interpret an ensemble forecast appropriately.
In addition to the formal business the days also provided an invaluable opportunity to meet and talk with fellow practitioners and experts in flood forecasting. Engagement of this sort is critical to the continued evolution of the forecasting service.