Changes in the land use and occupation and their influence in the urban climate of medium-sized cities

Abstract

Urban development allows increasingly large populations to occupy new horizontal and vertical spaces, whose changes in land use and occupation, consequently, is one of the factors that cause the so-called Climate Changes, thus, requiring studies about the expansion of cities. The objective was to analyze the changes in land use and occupation and, consequently, the influence on the urban climate of two medium-sized cities who are going through these transformations, La Serena (Chile) and Piracicaba (Brazil). For this, we used three tools: (i) geoprocessing of thermal images from the Landsat-7 satellite, among years 1999 (oldest in the collection) and 2018; (ii) thermal camera and infrared digital thermometer, capable of verifying the surface temperature (TS) at the microclimate level; (iii) ENVI-met model, responsible for simulating interactions between surface-plant-air. Respectively, the results showed an average increase in TS estimated at 1°C every five years, with the greatest impact on La Serena, which had more than two thirds of its area heated. Measurements in loco revealed the potential of urban forest to mitigate extreme TS, such as 70°C of asphalt or an incredible 95°C on the roof of dark cars, stabilizing them in the range between 30°C and 40°C in the hottest time of the day, by reducing the air temperature by 1°C. Finally, the computer simulations revealed the need for homogeneous distribution of urban forest, since the influence of the Central Square in Piracicaba was restricted to a radius of 100 m. In addition, the simulations helped to understand how urban design changes the microclimate, revealing the results of decisions taken by its public administrations.