The effects of urban agricultural areas on the intensity of the heat islands in Florianópolis - SC

Author(s)

Gustavo Henrique Pereira da Silva

• Document type: Master's Dissertation
• Press: Presidente Prudente. 2020-06-16.
• Institution: Universidade Estadual Paulista (Unesp). Faculdade de Ciências e Tecnologia. Presidente Prudente
• Defense date: 2020-04-02
• Advisor: Margarete Cristiane de Costa Trindade Amorim

Abstract

The accelerated growth of cities associated with inefficient planning has caused numerous environmental issues that affect the population quality of life. In this context of changes in natural environment conditions, several scientific studies have been carried out, among which stand out those who focused on studying the climate of cities. Therefore, the present research was based on the theoretical and methodological proposal of the Urban Climate System (UCS), with emphasis on the thermodynamic subsystem. The main objective was to investigate the effects of urban agricultural areas on the intensity of heat islands in Florianópolis - SC, with regard to temperature conditions, one of the main climatic elements responsible for thermal comfort. The emphasis given to Florianópolis is related to the presence of a legal framework that provides for the implementation and support of agricultural practice in intra-urban and peri-urban spaces. The methodological procedures performed consisted of researching temperature data using remote sensing techniques and fixed points. Landsat-8 satellite images were treated and analyzed, which presented differences in the thermal characteristics of the targets, comparing densely built areas with non-built spaces, revealing intensities of surface heat islands of up to 14ºC. The areas with the highest vegetative development, with emphasis on those located at the top of hills, presented the lowest temperatures in the scenes, and the areas of urban and peri-urban agriculture were up to 8ºC less heated than densely occupied areas. Such result revealed an inversely proportional relationship between the values of surface temperatures and Normalized Difference Vegetation Index (NDVI). The 12 monitored fixed points, distributed in the urban grid, enabled the collection of air temperature in February and March 2019. The monitored sites showed thermal variations at different times of the day, which is associated with the uses and occupation of the surrounding land, the performance of different atmospheric systems, the incidence of solar radiation, etc. The elongated shape of the Santa Catarina island in North-South axis, provided in its 54 km of extension particularities to the local atmosphere, which were observed mainly during daytime (6 am, 9 am, 12 pm, 3 pm), in which the points located to the South from the island (points 1, 2, 3 and 4), including those of urban agriculture (points 1 and 2) with vegetation cover, were hotter than the others. At night, mainly under stable atmospheric conditions, it was observed that urban points, with emphasis on those located in more densely occupied areas, registered the highest thermal intensities, with up to 4ºC. During nighttime, in many days of analysis, the areas of urban agriculture became islands of freshness, which highlights the importance of this type of land use in reducing temperatures in an urban environment. (AU)

• FAPESP's process: 18/08308-8 - Urban and peri-urban agriculture and its effects on intensity of urban heat island in Florianópolis-SC
• Grantee: Gustavo Henrique Pereira da Silva
• Support Opportunities: Scholarships in Brazil - Master