Probabilistic approaches for improved flood risk assessment and management under consideration of uncertainties

One of the challenges faced by Member States in implementing the Floods Directive is how to factor in uncertainties in flood hazard and flood risk assessments within flood risk management strategies. Tools are needed to support decisionmaking on appropriate flood measures under consideration of uncertainties.

Probabilistic methods quantify and visualize uncertainties by providing results as a set of potential values with their corresponding probability of occurrence. The research project IMPREX shows how the implementation of the Floods Directive could benefit from the use of probabilistic approaches in calculations on flood occurrence and flood damage:

• Probabilistic flood occurrence projections could improve flood hazard maps depicting uncertainties of potential flood scenarios, including climate change impacts
• Probabilistic flood damage assessments foster a more realistic understanding of potential flood risks and can help identify more efficient risk management measures
• Probabilistic approaches can improve early warning by extending lead times for water level and river discharge forecasts
• Probabilistic approaches can bolster more rational decision-making, e.g. in the context of drawing-up flood risk management plans, by factoring in all the possible hazards and risks