A Multi-Hazard Model for the City of Lisbon, Portugal

In recent decades the topic of exposure to natural hazards has gained prominence due to the rise in natural and man-made disasters that might particularly damage urban areas. Population growth, urbanization and climate change are just a few of the reasons that have led to an increase in catastrophes, as well as increased community awareness of the issue. To effectively mitigate these phenomena, it is required a comprehensive assessment of the various hazards that often affect a region. The relevance of the topic is contained in the international development agenda concerning the assessment of multi-hazard risks as one of the guiding concepts in the Sendai Framework 2015-2030, therefore several approaches for assessing vulnerability and risk have been presented throughout the years. However, the majority of them only analyse one hazard at a time, and there are currently few approaches that examine many threats at the same time. Disaster mitigation plans must thus consider all the hazards as a whole to preserve the built environment and reduce both economic and human losses. The current study aims to propose a multi-risk model for the city of Lisbon, which, like many other cities throughout the world, faces several threats that endanger its population, infrastructure, and economy. To limit these risks and build effective disaster response plans, a comprehensive multi-risk assessment that accounts for earthquakes and floods has been evaluated. To achieve these results, the proposed study utilised satellite remote sensing technique data and GIS tools to obtain a spatial distribution of the elements at risk. Flood and earthquake vulnerability have been evaluated for every building in the study area and damage scenario has been assessed for each return period. For the evaluation of seismic vulnerability, the Risk-UE method has been applied while for the flood vulnerability assessment, a complex hydrological model for rainfall scenario was considered. Furthermore, the expected losses have been estimated and combined for a multi-risk evaluation. This process enables the city's most vulnerable areas to be prioritised. The main outcomes gained constitute a significant step forward in the implementation of community preparedness programmes, as well as the adoption of appropriate urban mitigation strategies that account for potential hazards to increase cooperation between responders and local authorities.