Tangible and intangible ex post assessment of flood-induced damage to cultural heritage

Floods pose significant risks to cultural heritage (CH), yet post-disaster damage data on CH remain lacking. In this paper, we address this gap by focusing on the ex post assessment of flood-induced damage to CH. The method involves the identification of damaged assets and a field survey to assess loss in tangible value (LTV) and loss in intangible value (LIV). The potential contributing factors, e.g. water depth and river slope, are analysed through geospatial analysis. Ex post damage data on CH are compared with the outcome of an ex ante analysis based on available methods to verify the quality of exposure data and possible limitations. The method is applied to the 15-16 September 2022 flood event that occurred in the Marche region (Italy). The survey involved 14 CH in 4 municipalities and 3 catchments. Results highlight the inadequacy of existing exposure data for ex ante damage assessment and the importance of building characteristics. However, ex post data confirm that religious architectures are likely to suffer the highest LTV and LIV. The ex post damage analysis provided a semi-quantitative evaluation of both LTV and LIV in relation to flood characteristics. Notably, significant correlations between LTV and flood depth, as well as with the slope of the riverbed (a proxy for river flow velocity), were found. LIV correlates well to flood depth and river slope albeit with lower R2 and larger RMSE, highlighting that intangible impact analysis requires more effort than hazard characterization. Further research should increase the availability of ex post damage data on CH to form the basis for damage model validation and development of empirical vulnerability functions.