Development of a European flood forecasting system

TLDR

Recent advances in meteorological forecast skill now enable significantly improved estimates of precipitation quantity, timing, and spatial distribution up to 10 days ahead at 40 km scales. The study aims to develop a European Flood Forecasting System and assess its flood‑forecast skill for specific basins, meteorological events, and prediction products. The system downscales 40‑km precipitation forecasts to 1–5 km using regional NWP models, drives high‑resolution hydrological and hydraulic models, and produces probabilistic n‑day discharge exceedance risk maps for Europe at 5 km resolution that can be updated as lead time shortens. Initial results from a hindcast of the January 1995 NW‑Europe floods (Rhine, Meuse) demonstrate the prototype system’s potential.

Abstract

Abstract Recent advances in meteorological forecast skill now enable significantly improved estimates of precipitation quantity, timing and spatial distribution to be made up to 10 days ahead for model scales of 40 km in forecast mode. Here we outline a prototype methodology to downscale these precipitation estimates using regional Numerical Weather Prediction models to spatial scales appropriate to hydrological forecasting and then use these to drive high‐resolution scale (1 or 5 km grid scale) water balance and rainfall‐runoff models. The aim is to develop a European Flood Forecasting System (EFFS) and determine what flood forecast skill can be achieved for given basins, meteorological events and prediction products. The output from the system is a probabilistic assessment of n‐day ahead discharge exceedence risk (where n < 10) for the whole of Europe at 5 km resolution which may then be updated as the forecast lead time reduces. At each stage the discharge estimates can be used to drive detailed (25–100 m resolution) hydraulic models to estimate the flood inundation which may potentially occur. Initial results are presented from a prototype version of the system used to perform a hindcast of the January 1995 flooding events in NW‐Europe (Rhine, Meuse).