Representing multi-hazard events in urban systems: An ontology-based model

The United Nations World Cities Report 2022 predicts that global urbanization will increase from 56% in 2021 to 68% in 2050. This will lead to consequences, including the impact of natural, environmental, and anthropogenic risks on cities. These risks will manifest as physical damage to buildings and adverse effects on services to the population and socio-economic structures, as well as losses of life. Cities are adaptive complex systems with intricate interactions between inhabitants and infrastructure, often compared to living organisms. As system complexity increases, understanding and sharing information become more challenging. One alternative to address these challenges is the development of ontological models that use modeling languages to capture the shared semantics of specific parts of the world and their perceived reality, thereby improving understanding and information sharing. Although there are ontological models and taxonomies in the literature that address topics such as cities, population, urban infrastructure, and the geosphere, few represent these elements coexisting and from different perspectives of risk and hazards. Moreover, most of them do not use foundational ontologies, which can lead to inconsistencies and validation drawbacks. The purpose of this paper is to contribute to the multi-risk analysis in urban systems and risk reduction by addressing the aforementioned gaps. To this end, a risk-driven ontological model of urban systems is proposed. This model is based on a foundational ontology and integrates the main elements of an urban system. In addition, a thesaurus was implemented and made available online on an open-source platform (Skosmos platform) that is easily accessible to both experts and laypeople. The results were validated with stakeholders through case studies, storylines, and interviews.