GIS-Based Urban Heat Island Mapping and Analysis: Experiences in the City of Bologna

Climate change effects have become increasingly visible recently through extreme weather events, such as heat waves. These are strictly related to a two-way relationship with urbanization. Indeed, urban expansion due to population migration from rural to urban areas impacts energy consumption, soil sealing with vegetation loss and gas emissions. Moreover, due to their characteristics, cities experience the typical urban heat island microclimate and are more vulnerable to heatwaves. In this context, having insight into the land surface temperature and accurate knowledge of city characteristics is essential to wise decision-making to ensure a more sustainable livelihood. The present paper provides an overview of two different approaches useful for thermal mapping at the city scale, implementing GIS-based analysis integrating local surveys with geospatial data. In particular, the city of Bologna (Italy) is studied. In the first study, temperature measurements along a transect was taken on March 19, 2021, with a mobile system. Then they were corrected considering data from some weather stations interpolated with Kriging, which shows the highest correlation coefficient of 0.99. The corrected temperature correlated at 0.69 with remote sensing NDVI data. The second study analyzed the significant impact of urban morphology, particularly building density, on temperature variations; it emphasizes the need for strategic urban planning to mitigate the Urban Heat Island effect.