MOVIDA: a procedure for flood damage assessment and mapping at the river district scale

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 (FRMPs), 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 results obtained by the damage modelling group, composed by 8 universities and the CNR, within the project MOVIDA (MOdello per la Valutazione Integrata del Danno Alluvionale – Model for integrated evaluation of flood damage).
The objective of the project was to provide an Information System able to perform an analytical evaluation and mapping of expected damage, overcoming the limitations of present maps where the evaluation of risk remains highly qualitative and subjective. First, proper exposure and damage assessment tools were identified, for all the categories of exposed elements included in the Directive: population, infrastructures, economic activities (classified as: residential buildings, commercial and industrial activities, and agricultural activities), environmental and cultural heritage, and na-tech sites. These tools address specific requirements: (i) being valid/applicable for the whole District, (ii) being based on standardised and institutional data, available at national level, (iii) being calibrated (and possibly validated) in the Italian context. Second, the dedicated open-source Geographic Information System ISYDE (open-source Information SYstem for Damage Estimation) was developed to support technicians in the implementation of the proposed tools and in the visualisation and processing of damage results. Finally, ISYDE was transferred to Regional Authorities for flood damage evaluation and mapping to all areas at significant risk in the Po District.
Results of damage assessment are collected in dedicated sheets (one for each area) and are presented by means of tables, graphs, and maps, in order to provide both the overall expected damage in a specific area as well as its spatial distribution, for all the five categories of exposed elements. The new developed maps represent a significant improvement with respect to the previous ones, supporting the Cost Benefit Analysis (CBA) of mitigation measures to be defined in FRMPs. Indeed, they enable the identification and localization of typological and spatial hotspots within a single area as well as the comparison among different scenarios, in terms of CBAs.