Flood early warning and forecasting across Europe - an insider's view by IMPREX Early Career Scientists
Meteorological and hydrological processes causing floods vary greatly across Europe, from coastal flooding and compound events in The Netherlands to convective flash floods in Spain and massive flooding events in the Rhine, Elbe and Danube basins in Central Europe. As such, the need to establish flood early warning and forecasting systems is a ground truth in all European countries. In most cases, the development and improvement of these systems was promoted by a single disastrous event (or a succession of events within a short period of time) that pushed the administrations towards the need to avoid future similar phenomena.
While all of them are unique, flood early warning and forecasting systems possess common features: the use of modelling procedures in different steps of the forecasting process, the integration of diverse sources of information as input, the need to reach the public (directly or indirectly) and the necessity to coordinate the different spatial and temporal scales found during the forecasting procedure. Nevertheless, the main common feature of these forecasts is the continuous improvement of their inputs, procedures and results, in response to the evolving factors that affect the flooding processes.
Below we describe from an insider point of view four forecasting services active in Germany, The Netherlands, Spain and at the pan-European scale.
‘Almost every state runs its own flood forecasting or warning centre […] the downstream centres base their forecasts on monitoring values and forecasts provided by those upstream.'
‘An extreme flood event was the decisive factor in Germany for the development of a national flood protection programme.’
‘Improving flood forecasting and warning facilities is not a singular issue […] it requires permanent effort.’
‘The Netherlands has a long history of dealing with floods, both from the sea and from fluvial flooding.’
‘What is special about forecasting the flow of the Rhine and the Meuse rivers is that most of the basin is situated outside the Netherlands.’
‘A hydrological model is used to model the runoff of the Rhine tributaries all the way up to its Swiss origins and these discharges are then routed through a hydraulic model of the river Rhine itself to also provide water levels.’
‘The starting point of the Spanish Flood Early Warning Systems, the SAIHs, was a single event. It happened on October 20th 1982 in the Lower Jucar basin.’
‘Each River Basin Authority has its own SAIH system […] each SAIH consists in an automatic data collection, transmission and treatment centre embedded in each River Basin Authority.’
‘The Spanish Government planned an improvement of the SAIH project in order to combine monitoring with forecasting.’
The European Flood Awareness System (EFAS)
‘Developed in 2003, following the disastrous floods in the Elbe and Danube basins in the summer of 2002.’
‘These flood events were a wakeup call, emphasising the need for improvements in flood risk and crisis management within and across national boundaries.’
‘A variety of products are displayed on the EFAS web interface, from which flood notifications can be issued.’