Efeito da urbanização no balanço de energia da superfície por sensoriamento remoto em Várzea Grande - MT

Abstract

Spatial and temporal distribution of the soil cover of a locality are fundamental to understand the environmental changes occurred in the process of urbanization. These changes can be quantified and analyzed using remote sensing. Várzea Grande in the state of Mato Grosso, Brazil is a city that has experienced high growth in the last decades, but it fits like a metropolis. This work aims to evaluate the effects of urbanization on spectral behavior and energy partitioning using Landsat 5 TM satellite images in a medium-sized urban area. The study was about Várzea Grande urban area 1986 and 2011, a place with a low density of urbanization. First, soil cover classification was performed with an algorithm generated with biophysical indexes. The surface temperature estimation, NDVI calculation, albedo and the SEBAL algorithm were used to estimate the energy balance. The classification of soil cover allowed to discern five classes for the urban area of Várzea Grande: dense vegetation; underbrush and / or shrub vegetation; exposed only; buildings and water. The classification had a high coefficient of agreement, Kappa, with values above 0.76. In the analyzed period, the area covered by the construction-related class grew by 600% and dense forest areas decreased by 85%. When comparing the data that underwent coverage conversion, there was an increase in NDVI and the surface temperature values showed a variation above 10 ° C. There was an increase in the means of sensible heat and decrease in the balance of radiation, latent heat flux and evapotranspiration. Therefore, from 1986 to 2011 urbanization modified the structure of the surface environment and the spectral behavior of the surface of this city. It was verified that even with favorable pluviometric conditions for the vegetation, the sensible heat flow increased and there was a decrease in the latent heat flux. It was concluded that the city of Várzea Grande underwent major changes in soil cover, which mainly altered the energy partitioning and surface temperature. The data obtained could lead to results that can be used for urban planning in order to promote improvements in thermal comfort for the population.