Efficiency assessment for the urban heat island mitigation measures in a city with an oceanic climate during the summer period: Case of Valdivia, Chile

Abstract

Urban heat islands are a phenomenon present around the world, affecting several areas of life. Various studies in Chile have considered this problem, but they are focused on the northern and central zones of the country. This phenomenon has been identified in cities in southern Chile as well; however, there is a lack of research to complement current information about urban heat islands in this region and present mitigation strategies. This study aims to analyse the urban heat island effect in a city in southern Chile during a warm season (southern hemisphere summer) using high-resolution computational fluid dynamic simulations and proposes efficient urban planning strategies to mitigate this effect. Four mitigation strategies were studied: tree cover, reflective pavements, water fountains, and a mixed strategy including all of the previous three. A representative urban area was selected, and through statistical analysis, a strong diurnal urban heat island was identified, principally due to the urban morphology of the case study. All strategies were effective, with the mixed one presenting the best results in this area. Tree cover could decrease the median urban heat islands intensity by 0.6 degrees C, changing the albedo decreased 0.94 degrees C, water fountains decreased 0.4 degrees C, and finally the mixed one could decrease 1.4 degrees C. However, the complexity of implementing these strategies must be taken into consideration. Our results can help urban planners to make better decisions according to available resources.