Urban Heat Island Mitigation: A GIS-based Model for Hiroshima

The phenomenon of overheating in urban areas is an increasingly important issue as far as the quality of life and public health are concerned. This paper proposes a simple model, integrated with a Geographic Information System (GIS) tool, that can be used to analyze the microclimate of outdoor spaces, considering the relationship between the air temperature and the characteristics of an urban environment. The Urban Heat Island (UHI) effect was analyzed by assessing parameters that describe the urban context, such as the density of the population and of the buildings, and the urban morphology. Remote sensing data and satellite images were used to evaluate the presence of vegetation and the type of surfaces in the urban space. Through the construction of linear regression models, the main variables of influence were identified for a typical summer day. It has been found, from the results, that the UHI effect decreases proportionally with the presence of vegetation and with higher values of the albedo of urban surfaces, as well as of the altitude and the distance from the sea. The UHI effect instead increases proportionally for higher values of the canyon height-to-width ratio, the building density and the Land Surface Temperature. These models can be used to analyse the outdoor thermal comfort and the livability of an urban territory.