On the update of flood hazard and risk maps in the Po River District: results obtained for flood damage modelling

The European Floods Directive (2007/60/EC) requires that Member States develop flood hazard and risk maps, to be used as the information basis for the development of Flood Risk Management Plans, and to update them every 6 years. To support such a process, the Po River District Authority signed in May 2020 an agreement with 20 Italian Universities and the Italian National Research Council (CNR) with the aim of transferring the state of the art about hydrology (including climate change), hydraulics and damage modelling into the production of the new maps, to be delivered by December 2021. This contribution describes the activities done so far by the damage modelling group, composed by 8 Universities and CNR. The objective of the group is to provide an Information System able to perform a quantitative estimation of flood damage, overcoming the limitations of present maps where the evaluation of risk remains highly qualitative and subjective. Proper damage assessment tools were identified for all the five categories of exposed elements included in the Directive: population, infrastructures, economic activities, environmental and cultural heritage, and na-tech sites. These tools are thought to address specific requirements: (i) being valid/applicable for the whole area of the District, (ii) being based on standardised and institutional data, available at national level, (iii) being calibrated (and possibly validated) in the Italian context. A dedicated Geographical Information System is currently under development to support technicians in the application of proposed tools and in the visualisation and processing of damage assessment results.  The work done so far suggests that a quantitative estimation of damage is not yet possible for all the categories, rather three different levels of damage knowledge can be reached depending on the category and available data: quantitative, qualitative or descriptive (the latter being based on a deep investigation of historical data). Therefore, in order to get a total damage figure, the need arises of (i) comparing damage data with different metrics and (ii) comparing and weighting damage to different exposed categories, whose values may depend on objectives at stakes. A participatory process with final users will be then set up in the next year, to guarantee the usability and applicability of developed tools.