A compact multi-hazard assessment model to identify urban areas prone to heat islands, floods and particulate matter

Abstract

Urbanization and climate change intensify environmental hazards such as the Surface Urban Heat Island (UHI) effect, the concentration of Particulate Matter 10 micrometers or less in diameter (PM10) and flooding. These hazards are common in cities, driven by factors such as land cover changes, energy consumption, road traffic, soil sealing and proximity to water. To address the gaps identified in previous studies, which focus on modelling single hazards and/or use many variables, we developed a compact multi-hazard assessment model to identify urban areas prone to the three hazards mentioned. A reduced number of variables were processed using Geographic Information Systems (GIS) and Multi-Criteria Decision Analysis (MCDA) to model each hazard and then combine the results into a composite multi-hazard metric. The criteria weights were optimized based on observed values of SUHI, PM10 and floods in the city of Santander (Spain), where the model was tested. The results showed a strong correlation between our multi-hazard map and the observed data, suggesting that using few variables can effectively identify hotspots with heightened combined impacts of these hazards. The most critical areas were found in the central and southwestern parts of the city, where infrastructure and artificial surfaces with lower albedo and permeability, as well as high traffic volumes, predominate. Accordingly, strategies to counteract the effects of these hazards should consider a shift in urban design, emphasizing light-colored, porous pavements and various forms of vegetation. These measures contribute to thermal regulation, runoff control and air purification, thus contributing to make cities more resilient.