Evaluation of water depth - damage functions in built-up areas in Sardinia (Italy)

Flood events occurring in the Mediterranean area lead to investigate on relevant damages caused by flooding in urbanized areas. The EU Flood Directive 2007/60, requiring a cost-benefit analysis for the definition of mitigation measures, should be supported by appraisals of flood damages. Recent studies recognise the use of water depth- damage functions as key elements in the decision-making process of mitigation measures and should be developed specifically considering regional territory features. This paper confirmed application of the Joint Research Centre (JRC) model approach considering studies developed for the Sardinian region and providing water depth-damage functions for direct tangible damage assessment in this region. Historical data on flood damages were collected considering two recent flood events and relations between water depth and expected damage are proposed using a Pearson III probability distribution. The obtained water depth-damage functions show different trends due to building types in the two studied areas. The procedure was subsequently implemented considering synthetically generated flood events in order to estimate the expected mean annual damage values due to flooding in prone areas and to verify the economic efficiency in planning mitigation measures. Aiming to confirm the study results reliability, the case study of Olbia town was accurately analysed. In particular, Olbia water depth-damage function was applied for synthetic floodplain scenarios generated with occurrence of 50, 100, 200 and 500 years to observe potential damages and to conduct a comparison with the occurred case.