After receiving an EFAS notification, there is a set of actions that can provide insights on the forecasted flood events. Below we summarize a general procedure and products to ease understanding the predicted hydrological condition using the EFAS-IS. There are three different types of notification sent to EFAS partners: Formal and Informal Flood Notifications as well as Flash Flood Notifications.
EFAS forecasts are checked twice a day by officers on duty from the CEMS Floods Analytics and Dissemination Centre. You will receive an EFAS notification when EFAS predicts a significant probability of flooding in your area based on the different reporting point layers in EFAS IS (“Reporting points” and “ERIC Reporting points”, Figure below). This can be a Formal Flood Notification when all criteria are met or an Informal Flood Notification when some of the criteria are not met, but the analysis still suggests a need for action. Flash Flood Notifications are sent based on ERIC Reporting points that are representative for smaller catchments (< 2000 km2) and faster catchment responses.
Reporting point layers from the Flood Summary and Flash Flood menus in EFAS-IS. Formal and Informal Flood Notifications are based on Reporting points (squares), and Flash Flood Notifications are based on ERIC reporting points (triangles).
When receiving a notification, a first step could be to check the event in the EFAS-IS and to analyse auxiliary information provided in the EFAS Map Viewer (see detailed description on the most important layers in section 3.2.2 "Layer categories explained"). Active notifications can be displayed on the map by clicking on the warning triangle in the menu bar (third from the right side (), active notifications are being displayed when the triangle in the menu bar is green). All active notifications then show up on the map as triangles as well as in a list on the left side with the most recent notification on top (Figure below). There are three different triangles in the map representing the different flood notifications (formal, informal and flash flood) which are also represented through different colours in the list. Red represents Formal Flood Notifications, orange Informal Flood Notifications and blue Flash Flood Notifications. Clicking on the coloured box in the list to the left zooms in to a single active notification. Clicking on the mail symbol () opens the notification that was sent to the partner and provides more details on the event, like the predicted peak time or the probability of exceeding a 5- and 20-year return period.
Active Flood Notifications displayed on the map.
In general, it is suggested to analyse the discharge hydrograph and how the different forecasts compare to each other to get an indication on the associated uncertainties of the forecast. You can access the figures by clicking on a reporting point (coloured squares from the "Reporting points" layer under the Flood Summary menu () or ERIC reporting point (coloured triangles from the "ERIC Reporting Points" layer under the Flash Flood menu ()).
Other suggested layers for the analysis of Formal and Informal Notifications are:
• Model performance and Forecast skill (both under the Evaluation menu, )
• Initial conditions (several variables available, )
• Expected consequences ("Rapid Flood Mapping" and Rapid Impact Assessment" layers from the Flood Summary menu, )
Suggested layers for the analysis of Flash Flood Notifications:
• Landslide susceptibility (found under the Static menu, )
• Soil moisture (Initial Conditions menu, )
• Affected area and accumulated precipitation (Flash Flood menu, )
Apart from the information provided through EFAS, the users' expert knowledge and the information from national forecasting and warning services is an invaluable additional source of information to verify or disprove the EFAS forecasts.
In the email for Formal, Informal and Flash Flood Notifications, an EFAS partner will always receive a link for leaving feedback on that notification. It is generally recommended to provide feedback on the quality of the EFAS notifications as this is a very direct way to improve and to some extent influence the products and services provided through EFAS.
In addition to the information compiled here, a detailed description of possible actions after receiving a notification can be found in the EFAS webinar from 15 December 2021.