Assessment of Population Health Risks Due to Heat Islands Using Thermal Satellite Images (The Case of Valencia)

Heatwaves, have been made more frequent and intense in the last decades due to climate change and have been severely impacting the population, especially vulnerable ones, causing illness, death and impact on productivity. Heatwaves and their consequences are worst in urban areas that become islands of higher temperatures, usually refereed to as urban heat islands, UHI. In the framework of the European Commission-funded research project ARCH: Advancing Resilience of historic areas against Climate-related and other Hazards this phenomenon has been analyzed with special focus on historic and cultural heritage areas. This paper proposes an easy to be implemented procedure to provide to local administrations and stakeholders readable and easy to be understood information on the location of UHI within the territory and the induced risks of impact on the population, enabling them to take informed decisions on possible and effective mitigation strategies. The proposed procedures use satellite thermal maps to quantify the thermal hazard within the analysed territory in the first instance; the exposure to UHI effect in terms of location and severity of possible urban islands within the city is evaluated by considering both the land cover and the population. A social vulnerability assessment is then performed based on age and economic indicators readily available from census data. Using a fuzzy overlay approach all the above-mentioned assessments are combined to estimate the risk for possible impacts to the population induced by heatwaves.