by Gwyn Matthews, CEMS Hydrological Forecast Centre – Computational (COMP)
What is EFAS Post-Processing Forecast?
EFAS post-processing aims to correct errors and quantify the uncertainty in the EFAS forecasts by using statistical techniques and real-time discharge observations. It is applied to the EFAS medium-range forecast multi-model ensembles to create a new set of probabilistic forecasts. These forecasts are shown in the pop-out window of the reporting point layer as the ‘Real-time Hydrograph’ alongside two bar charts showing the probability of the flow exceeding two observation-based flood thresholds, respectively. The forecast data of the EFAS Post-Processed Forecast (EFAS PPF) can be accessed via the CEMS Sensor Observation Service (CEMS-SOS), a password-protected service available to EFAS partners.
In 2022, the EFAS post-processing method was upgraded to 6-hourly and applied twice daily to 1608 stations for which EFAS partners provide historic and real-time river discharge data, shown as blue markers in the reporting point layer when there is no flood signal.
EFAS PPF at the 17th EFAS Annual Meeting
The EFAS Post-Processed Forecasts were the topic of one of the hybrid workshops co-organised by the CEMS Hydrological Forecast Centre – Computational (COMP) and the European Union’s Joint Research Centre (JRC) during the 17th EFAS Annual Meeting in September 2022. As well as being a refresher on what is EFAS PPF (see presentation here), the aim of the workshop was also to explore limitations and identify potential future developments of the EFAS PPF with the EFAS partners. During the 1h15 workshop, 41 attendees (21 face-to-face) worked together with the organisers on five topics (see bullet points). Pre- and post-workshop questionnaires were also distributed to gather anonymous and individual responses.
Access: How easy and efficient it is to access the EFAS PPF product and data?
Product Design: Is the visualisation and information content of the EFAS PPF product intuitive and usable?
Method: Does the statistical-correction method address users’ needs?
Training and Documentation: Is the EFAS PPF documentation on methods, products, workflow, and data requirements clear enough?
Evaluation: Are the EFAS PPF evaluations performed often enough and reported in a clear way?
EFAS PPF: the good, the bad, and the confusing
A face-to-face and online mind-mapping activity (using miro for online participants) provided a structured way of exploring the limitations and advantages of the EFAS PPF and potential directions for future evolution (see figure).
From the mind-maps, questionnaires, and post-workshop discussions with the EFAS partners, COMP and the JRC identified key areas for improvement which are summarised in the table below.
Shaping the future of EFAS PPF
We would like to thank all the EFAS partners who participated in the workshop for sharing their opinions and ideas. In the figure below we have outlined a proposed plan for including the development to the EFAS PPF into the operational EFAS system.
Several of the developments discussed above could be implemented in different ways. To ensure that only the most appropriate changes are implemented operationally we will contact individual EFAS partners for their input and feedback once prototypes have been created. If an EFAS partner would like to be contacted regarding developments to EFAS PPF impacting a specific region or if an EFAS partner has further feedback/comments or any questions regarding the EFAS PPF or the proposed plan then please use the ‘contact-us’ form on the EFAS-IS: https://www.efas.eu/en/form/feedback.