The role of vegetation in attenuating the Urban Heat Island (UHI): a case study in Guimarães, Portugal

Abstract

The Urban Heat Island (UHI) phenomenon, characterized by elevated temperatures in urban areas compared to their surroundings, is caused by the high density of impervious surfaces in built-up areas, which absorb and retain heat, and by the concentration of heat-generating activities in urban spaces. UHI can compromise occupational safety by increasing heat stress, reducing productivity, and raising the risk of accidents. This study analyzes the role of vegetation in attenuating the UHI effect by focusing on the city of Guimarães, Portugal. For this purpose, two transects traversing urban and vegetated spaces were selected in the central area of Guimarães, where air temperature and humidity data was collected. Thermal imagery from LANDSAT 8 was also utilized to analyze the land surface temperature (LST) of different land covers. The results indicated that built-up spaces consistently exhibited higher air temperatures compared to the average (up to 2.5 ºC), with LST values were up to 8 ºC higher than those of vegetated spaces. The study offers further evidence supporting vegetation as a nature-based solution that can effectively mitigate the adverse health and environmental impacts of UHI.