Flood damage risk assessment optimizing a flood mitigation system

Flood risk management plan for potentially damaged areas is a main requirement from the European Directive 2007/60. Therefore, assessment and evaluation of the potential flood damages in quantitative terms need to be defined in mapped flood risk areas. Quantitative evaluation should be in agreement with the required cost-benefit analysis as a rational decision-making tool optimizing the flood mitigation system. In the first part of the paper, analyses are reported, based on recent flood events that had taken place in the Europe, in order to obtain depth-damage functions to apply in the Sardinia region (Italy). Flood damage functions are not still available for every European country and the paper analysed previous studies to define depth-damage functions for this region. The paper focuses then on the validation of the proposed depth-damage functions. The available flood data and reported damages of the massive storm happened in South-Est Sardinia the 22nd of October 2008 are analysed. Data analysis allows to compute the total economic losses for different land uses conditions and to compare with the evaluated ones. In the last part of the paper, expected damages evaluated using depth-damages functions are used for the Coghinas river lowlands valley. The regional Water District Authority defining the flood risk management plan considers this river basin as a pilot area. Applying hydraulic models to floodplain river flow allows evaluation of the expected flood damages using the depth-damage functions. Moreover, the procedure allows developing the cost-benefit analysis in order to justify different design scenarios and gives a rational decision-making tool optimizing the flood mitigation system