A staggered approach to flash flood forecasting - case study in the Cévennes region

Abstract

A staggered approach to flashflood forecasting is developed within the IMPRINTS project. Instead of a single solution system, a chain of systems of different models and input data are being proposed that act in sequence and provide decision makers with information of increasing accuracy in localization and magnitude as the events approach. The first system in the chain is developed by adapting methodologies of the European Flood Alert System (EFAS) to forecast flashfloods and debris flows (EFAS-FF/DF) and has the potential to provide early indication for probability of flashfloods on European scale. The last system in the chain is an adaptation of the database model (DBM) to probabilistic numerical weather predictions (NWP) and observed rainfall, with the capability to forecasts river levels up to 12 hours ahead. The potential of both systems to provide complementary information is illustrated for a flashflood event on 2 November 2008 in the Cevennes region in France.