Flooding Pedestrians’ Evacuation in Historical Urban Scenario: A Tool for Risk Assessment Including Human Behaviors

Abstract

In the future, safety in historical city centers will be significantly affected by climate change-related disasters, such as floods. Risk assessment in these scenarios requires the combination of a series of factors: possible events characterization; urban layout configuration, its influence on flooding spreading and induced environmental modification; human factor, especially during first emergency phases. Historic urban scenario features (e.g.: compact urban fabrics; position near floodplains; possible inefficient early warning systems) additionally increase individuals’ risks. According to a “behavioral design” approach, developing flood evacuation simulation tools would help safety designers in assessing population’s exposure and then in suggesting emergency strategies to help citizens during such hazardous phases. This paper proposes a flooding evacuation simulation tool, which jointly represents the individuals’ evacuation motion towards safe areas, and the floodwaters spreading in the urban scenario. In particular, the simulator is founded on previous literature results concerning emergency behaviors and motion quantities (e.g.: evacuation speed as function of floodwaters flow) and adopts an agent-based model architecture. A part of the historic city center of Senigallia, an Italian city that suffered a significant flood in 2014, is chosen as application case-study to show tool capabilities. Results outline risk levels for individuals, and evidence critical points (in the urban space and during the time) for man-floodwaters-environment interactions (e.g.: being swept away by floodwaters). By evaluating probable evacuees’ choices in different scenarios, the tool is proposed to check the effectiveness of solutions for reducing evacuation process risks (e.g.: emergency planning; architectural elements development; interventions for floodwaters collection also in urban scenarios).