From critical urban context to heatwave-related hotspot. An exposure-based application for a study case in the metropolitan area of Naples

Abstract

KEYWORDS: climate risk, climate resilient design, urban settlements INTRODUCTION. Urban areas face environmental multi-risk conditions involving biophysical and socioeconomic subsystems, leading to complex interactions. Recent research focuses on compound risks resulting from hazard interactions, posing challenges in defining impacted exposed urban systems by multiple events. Nevertheless, several enhancements about the methodologies are to be addressed, to identify urban areas with the highest compound risk impacts. Therefore, to provide an overview of the risk arising from climate change a multidisciplinary approach to assess climate-related disaster risks is needed, considering all aspects contributing to increase hazards, exposure, and vulnerability. Within this thematic framework, it is important to identify factors defining an urban context as environmentally critical. Such urban contexts represent areas where single or interconnected hazards, along with exposure and vulnerability conditions, determine higher risks. These higher-risk areas are hotspots where to take action with climate-resilient strategies to reduce vulnerability.   OBJECTIVES. The goal of the contribution is to develop a conceptual framework for modelling multi-risk conditions in urban and metropolitan areas throughout a taxonomic knowledge of critical urban contexts. Specifically, the contribution aims to identify heatwave-related hotspots as locations where there are additive effects of hazards and overlapping impacts.   MATERIALS AND METHODS. The methodology for urban settlements’ analysis integrates soft, hard, and demographic systems, separating physical and functional-service aspects. The physical part includes Green, Grey and Population subsystems with different features: built-up areas (Grey), natural services and green systems (Green). The methodology has been applied in the study case of Nola city, in the metropolitan area of Naples. The thematic maps, resulting from the analysis of these sub-systems, has been overlapped with environmental, technological, functional-spatial elements and exposure factors like population distribution. The relationship between urban critical context assets (built-up features, road traces, geomorphologic conditions, natural and green elements, socio-economic conditions, etc.) and key environmental factors identifies hotspots. This knowledge model evaluates the inherent vulnerability of physical subsystems using indicators such as phase shift, attenuation, albedo and NDVI for built-up system (buildings and outdoor spaces). Exposure is only related to the population. RESULTS AND CONCLUSIONS. The results show that the built-up system behaves inadequately to heat waves. The impermeable surfaces are 26% and located in the historic centre. About 12% of the population, children and old people, are weaker to heatwaves negative effects. The experimentation allows to develop a knowledge model for the identification of the hotspots, and to support climate-resilient design choices for the reduction of the vulnerability to heatwave, based on the exposed population. The contribution is developed within the research Partenariato Esteso PE3, RETURN project (multi-Risk sciEnce for resilienT commUnities undeR a changiNg climate) (MUR Project Number: PE00000005), in the framework of the Spoke TS1 - Urban and metropolitan settlements activities, and within Programma PON R&I 2014-2020 - Asse IV “Istruzione e ricerca per il recupero - 840 REACT-EU”, Codice Unico di Progetto (CUP) 65F21003090003.