Author(s): Paolo Tamagnone; Enrica Caporali; Alessandro Sidoti

Linked Author(s): Paolo Tamagnone, Enrica Caporali

Keywords: Pluvial flooding; Flood hazard assessment; Hydraulic modelling; Cultural heritage; Historical buildings

Abstract: During the past decades, engineering and natural sciences strived for understanding the risk of coastal and river flooding as well as developing risk management strategies and policies. Nowadays, in an era governed by continuous climate warm-up and unstoppable urbanization, the increase in intensity and frequency of extreme rainfall events is directing the attention of decision-makers on defending cities by pluvial flooding. Extreme rainstorms lead to the collapse of the urban drainage systems causing the inundation of streets and buildings before the stormwater reaches the receptor water channel. In addition to the risk for human life and asset losses, rain-related effects are increasingly threatening the cultural heritage in ancient towns. Historical buildings are often collectors of inestimable cultural and artistic heritage and require a high level of protection against natural hazards. In this study, we investigate the hazard related to pluvial flood to which the cultural heritage located in the most vulnerable areas of Santa Croce district (Florence, Italy) is exposed. This area is threatened by different sources of flood hazard: river flooding since it lies next to the Arno River; surcharging and overflowing of one of the main sewer conduits of the city, the Chiesi sewer pipe (named as the designer engineer Flaminio Chiesi); surface runoff flowing from the upper basin to the river. The comprehensive hazard assessment is carried out exploiting a 1D/2D dual drainage model so to simulate the interactions between all hydraulic phenomena occurring both on the surface and underground. Different scenarios are designed and simulated to evaluate each possible concatenation of events or failures. The hydraulic model is implemented at a multi-scale resolution including: the high-resolution digital surface model of the city and the Arno River, the public sewer network, and the internal Rainwater Drainage System (RDS) of the historical buildings. Detailed historical research and field surveys have been conducted for drawing the forgotten technical design of the internal RDS of the National Central Library of Florence. The hydraulic model allows highlighting the critical nodes within the drainage network and identifying which areas are more exposed and where to focus the rescue efforts in case of extreme events. Hence, the results may also help site and city managers to increase the emergency plans efficiency. Moreover, the purpose of the study is to propose suitable technical and functional solutions for protecting and decreasing the vulnerability of the cultural heritage in a context where planning structural defence works are hardly compatible with the historical urban texture.

DOI: https://doi.org/10.3850/IAHR-39WC252171192022885

Year: 2022