Resilience of art cities to flood risk: A quantitative model based on depth-idleness correlation

Cultural heritage (CH) is threatened by floods; however, the understanding of exposure and vulnerability is challenging and makes risk and resilience assessment rarely practiced. CH is crucial for post-disaster resilience, especially when the local economy is based on tourism. The work presents a novel framework for evaluating flood resilience, indirect impacts, and associated risk in art cities. The exposure of CH is estimated using the number of visitors as a proxy variable for the social appreciation. A new depth-idleness vulnerability function assigning a reopening time to flood depth is developed from post-event reports. A resilience model is conceived to (i) describe the recovery dynamics, (ii) estimate the indirect impacts in terms of lost visitors to CH for different probabilistic scenarios, (iii) calculate risk, and (iv) identify mitigation actions. The application of the model to the art city of Florence (Italy), a UNESCO site visited by approximately 10 million people a year, shows that a medium recurrence interval flood requires a recovery time of 351 days and causes a loss of 10.5 million visitors. The annual average number of lost visitors is 88,000 approximately. Resilience can be increased by accelerating the reopening and by reinforcing the attractivity of the city.