An operational procedure for rapid flood risk assessment in Europe

Abstract

Abstract. The development of methods for rapid flood mapping and risk assessment is a key step to increase the usefulness of flood early warning systems and is crucial for effective emergency response and flood impact mitigation. Currently, flood early warning systems rarely include realtime components to assess potential impacts generated by forecasted flood events. To overcome this limitation, this study describes the benchmarking of an operational procedure for rapid flood risk assessment based on predictions issued by the European Flood Awareness System (EFAS). Daily streamflow forecasts produced for major European river networks are translated into event-based flood hazard maps using a large map catalogue derived from highresolution hydrodynamic simulations. Flood hazard maps are then combined with exposure and vulnerability information, and the impacts of the forecasted flood events are evaluated in terms of flood-prone areas, economic damage and affected population, infrastructures and cities.An extensive testing of the operational procedure has been carried out by analysing the catastrophic floods of May 2014 in Bosnia-Herzegovina, Croatia and Serbia. The reliability of the flood mapping methodology is tested against satellite-based and report-based flood extent data, while modelled estimates of economic damage and affected population are compared against ground-based estimations. Finally, we evaluate the skill of risk estimates derived from EFAS flood forecasts with different lead times and combinations of probabilistic forecasts. Results highlight the potential of the real-time operational procedure in helping emergency response and management.

New insights into flood warning reception and emergency response by affected parties

“…This includes keeping preparedness high and supporting effective emergency response by affected parties even without prior flood experience and the push of extreme events . To further increase lead times and support an effective response, rainfall and flood forecasts, particularly in flash flood areas, should be further improved and complemented with uncertainty and impact assessments (Thieken et al, 2016b;Dottori et al, 2017). Effective and harmonized risk and emergency communication, e.g.…”

“…To support decisions, it is increasingly discussed to supplement warning information with information about potential flood impacts (e.g. Coughlan de Perez et al, 2015;Dottori et al, 2017).…”

Understanding epistemic uncertainty in large-scale coastal flood risk assessment for present and future climates

“…Large-scale flood risk assessments have emerged during the last decade, with multiple continental or global studies focussing on fluvial risks Dottori et al, 2016bDottori et al, , 2017 and fewer on coastal losses (Hinkel et al, 2014;Hallegatte et al, 2013;Vousdoukas et al, 2018a). The emergence of these assessments comes as a response to the growing demand for upscaled flood risk estimation under present and future scenarios.…”

Framework for Offline Flood Inundation Forecasts for Two-Dimensional Hydrodynamic Models

“…In a complex river system, an ensemble of inundation maps can be provided by comparing the discharge at existing gauges and at virtual gauges, introduced at the confluence of rivers. The ease of operational practise of the offline systems is well documented in previous applications such as ESPADA system in France, the Zambezi FloodDSS in Mozambique, in which the inundation database was produced using a 1D hydraulic model [15], and EFAS in Sara river basin [17]. Furthermore, there are major challenges in operational application of these systems, in particular: Recompilation of the database in major land-use changes, an exhaustive database to cover all possible scenarios, validation of the query to select the most optimal scenario, and real-time validation of the forecast.…”