Development of a flood damage model for urban drainage networks

Abstract

A thorough understanding and assessment of flood damage to network infrastructures is fundamental to assist both policy makers and managing authorities in mitigation and restoration actions against inundations and, consequently, in increasing the resilience of the territories at risk. This research work focuses on the estimation of potential impacts of floods on urban drainage systems, by proposing a general methodology that can be adapted to other typologies of networks. The method consists in the development of damage-dysfunction matrices, as proposed by Eleutério et al. (Nat. Hazards Earth Syst. Sci., 13, 983–998, 2013), for drainage systems, by adopting an expert-based approach. These matrices allow analysing physical, systemic and functional vulnerability of each component of the network under investigation and, therefore, identifying the potential transfer of dysfunctions between the different components. Regarding this last point, a hierarchy description of the network was developed, by means of an ad-hoc methodology, in order to assign a systemic vulnerability degree to each component, hence helping the managing authority to prioritize recovery actions in case of emergency. Nonetheless, by identifying the number and types of users (i.e. residents, businesses, institutions) connected to each sewage pipe, the potential adverse consequences of sewerage’s disruptions for society are investigated as well. As an example, the model has been implemented on the sewerage system in the municipality of Parma, Northern Italy, by using the Baganza River Flood in October 2014 as a case study in support of the work.