Evaluating the impact of post-processing medium-range ensemble streamflow forecasts from the European Flood Awareness System
Open Access
- 15 June 2022
- journal article
- research article
- Published by Copernicus GmbH in Hydrology and Earth System Sciences
- Vol. 26 (11), 2939-2968
- https://doi.org/10.5194/hess-26-2939-2022
Abstract
Streamflow forecasts provide vital information to aid emergency response preparedness and disaster risk reduction. Medium-range forecasts are created by forcing a hydrological model with output from numerical weather prediction systems. Uncertainties are unavoidably introduced throughout the system and can reduce the skill of the streamflow forecasts. Post-processing is a method used to quantify and reduce the overall uncertainties in order to improve the usefulness of the forecasts. The post-processing method that is used within the operational European Flood Awareness System is based on the model conditional processor and the ensemble model output statistics method. Using 2 years of reforecasts with daily timesteps, this method is evaluated for 522 stations across Europe. Post-processing was found to increase the skill of the forecasts at the majority of stations in terms of both the accuracy of the forecast median and the reliability of the forecast probability distribution. This improvement is seen at all lead times (up to 15 d) but is largest at short lead times. The greatest improvement was seen in low-lying, large catchments with long response times, whereas for catchments at high elevation and with very short response times the forecasts often failed to capture the magnitude of peak flows. Additionally, the quality and length of the observational time series used in the offline calibration of the method were found to be important. This evaluation of the post-processing method, and specifically the new information provided on characteristics that affect the performance of the method, will aid end users in making more informed decisions. It also highlights the potential issues that may be encountered when developing new post-processing methods.Keywords
Funding Information
- Engineering and Physical Sciences Research Council (EP/R513301/1, EP/P002331/1)
- Natural Environment Research Council (NE/S015590/1)
This publication has 74 references indexed in Scilit:
- Technical Note: The normal quantile transformation and its application in a flood forecasting systemHydrology and Earth System Sciences, 2012
- Decomposition of the mean squared error and NSE performance criteria: Implications for improving hydrological modellingJournal of Hydrology, 2009
- Ensemble flood forecasting: A reviewJournal of Hydrology, 2009
- A model conditional processor to assess predictive uncertainty in flood forecastingInternational Journal of River Basin Management, 2008
- Error‐correction methods and evaluation of an ensemble based hydrological forecasting system for the Upper Danube catchmentAtmospheric Science Letters, 2008
- Towards the characterization of streamflow simulation uncertainty through multimodel ensemblesJournal of Hydrology, 2004
- Hydrologic uncertainty processor for probabilistic stage transition forecastingJournal of Hydrology, 2004
- Hydrologic uncertainty processor for probabilistic river stage forecasting: precipitation-dependent modelJournal of Hydrology, 2001
- Bayesian theory of probabilistic forecasting via deterministic hydrologic modelWater Resources Research, 1999
- A New Approach to Linear Filtering and Prediction ProblemsJournal of Basic Engineering, 1960