Análise espaço-temporal da temperatura de superfície terrestre e índices derivados de sensoriamento remoto como subsídio para a implementação de soluções baseadas na natureza

Abstract

Nature produces and provides various benefits that are essential for maintaining biodiversity and the survival of living organisms. The replacement of natural areas by built environments in the process of urbanization results in a reduction of Ecosystem Services (ES) and the emergence of new environmental and social problems. In this context, methods of urban planning with Nature-Based Solutions (NBS) were investigated to address identified urban challenges, considering indicators of Ecosystem Services (ES). A systematic review was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and the Web of Science (WoS) database. A total of 16 articles were included in the review, and the results revealed a methodological framework organized in stages to identify potential areas for implementing NBS. The definition of objectives (environmental, social, and economic aspects), selection of priorities (urban challenges) and ES indicators (analysis criteria), and choice of evaluation techniques (Multi-Criteria Decision Analysis – MCDA and Geographic Information System – GIS) are essential steps in these methodologies. Priorities included stormwater management, biodiversity/ecological connectivity, access to green areas/social cohesion, social vulnerability, air pollution, and temperature regulation. Data on Land Use and Land Cover (LULC), Census, Remote Sensing (RS), and local studies/plans were commonly used to develop ES indicators. LST is an ES indicator associated with temperature regulation. Therefore, the temporal and spatial variability of LST (1984–2023) was evaluated in the Downtown District of Santa Maria (DSSM), a medium-size city located in a subtropical climate region in the State of Rio Grande do Sul, Brazil. The relationship between LST and RS indices related to: vegetation - Normalized Difference Vegetation Index (NDVI); moist surfaces - Normalized Difference Moisture Index (NDMI); built-up areas - Normalized Difference Built-Up Index (NDBI); and exposed soil - Normalized Difference Bareness Index (NDBaI) was also investigated. For this, data from Landsat 5, 8 and 9 was obtained and processed in Google Earth Engine (GEE) and QGIS. It was found that LST is inversely proportional to vegetated and moist surfaces. Hill regions in the DSSM acted as natural barriers to urban expansion, with a predominance of tree vegetation. Thus, LST was lower and NDVI and NDMI values were higher in these areas justified by the natural cooling effect of shading and evapotranspiration. In contrast, LST was directly proportional to built-up areas and exposed soil. High LST and NDBI were obtained in regions of urban expansion, influenced by the reflectance and emissivity of the material. Areas with exposed soil (agricultural activities) also showed high LST and NDBaI. The greatest variation in LST occurred in heterogeneous landscapes, in places with integrated green areas and built elements. This is evidenced by the average LST of DSSM neighborhoods, which reached an amplitude of 5,61°C between the first and last years of the analyzed time series. This difference can be attributed to changes in LULC, as neighborhoods with preserved natural characteristics exhibited lowest LST. This allowed the identification of priority neighborhoods for the implementation of strategies to mitigate or combat the adverse effects of high temperatures. The results of this thesis demonstrate the importance of integrated planning with the concept of NBS to address urban challenges, particularly the challenge associated with high temperatures, which can be exacerbated by the formation of heat islands and the effects of climate change. The study of alternatives to address urban warming should be prioritized, and in this sense, the design and execution of projects with NBS are encouraged to enhance ES.