O impacto da arborização viária no conforto térmico em diferentes cenários de cobertura arbórea

Abstract

Climate change is being highlighted by the increased frequency of extreme weather events. Among the consequences is the increase in temperatures and the intensity of heat waves, phenomena that are amplified in urban areas due to the changes that occur in urban morphology during the urbanization process. There is a clear need to create action plans for adapting to and mitigating urban warming at different scales. In this context, street tree planting becomes an important mitigation strategy, as long as that it is planned and implemented properly to guarantee the benefits to the microclimate and thermal comfort. Therefore, this research aims to evaluate the impact of street tree planting on thermal comfort, considering the tree cover index as the main evaluation parameter. In addition, analyzes and quantifies the effects of other influencing attributes: urban morphology, the size of tree specimens and the type of ground cover. Based on the climatic and urban context of the city of Cuiabá, two sections of the urban area were selected, characterized as LCZ 3 (low-rise buildings in a compact arrangement) and LCZ 4 (tall buildings in a sparse arrangement), according to the classification of Local Climate Zones (LCZ) of urban morphology. The method adopted was computer simulation using the Envi-met three-dimensional model to simulate the impact of different scenarios that vary the tree cover index. In this way, the climate variables Air temperature (o C); Average radiant temperature - Trm (o C), Relative humidity (%) and comfort index, PET (o C) was compared for a scenario without afforestation with other scenarios that vary the tree cover index. The results showed that street tree planting has no impact on air temperature and humidity, but does have a significant impact on temperature and on PET. The greatest impact occurred in the summer, reaching a 30o C reduction in Trm and a 7o C in PET, during the hottest period of the day (2pm), in the scenario with maximum tree cover. However, it was observed that other factors influence the effect, such as the urban morphology; the size of the trees, the arrangement, and the ground cover. Based on the relationships established between tree density in the sidewalk area and the impact on thermal comfort, the street tree index (IAV) is proposed to contribute to contribute to decision-making in the planning of green infrastructure on urban streets. At last, it can be concluded that street tree planting has an impact on reducing the temperature and the sensation of heat, but it is not enough to achieve thermal comfort in extreme heat conditions. It is also important to investigate the effect of the arrangement and height of species and to adopt other mitigation strategies to enhance the effect of temperature attenuation.