Impactos das mudanças de uso da terra em componentes do balanço radiativo em regiões administrativas de Brasília-DF.

Abstract

The present study aims to identify changes in components of the surface radiation balance, provoked by changes in land occupation and use in three administrative regions of the Federal District: Cruzeiro, Samambaia and part of Paranoá. To accomplish the intent of this study, were used images TM – Landsat 5 with low or no cloudiness representative of the dry and rainy seasons of the years 1985, 1989, 1995, 2000, 2005, 2007 and 2011. Were calculated the normalized difference vegetation index (NDVI), which represents the quantity of vigorous vegetation; the albedo, for being sensitive to changes in land cover; and the net radiation for quantifying the energy available for microclimatic processes. To calculate these variables the procedures adopted in the Surface Energy Balance Algorithm for Land – SEBAL were used. To evaluate possible alterations occurred in land use and coverage were used the meteorological parameters collected by the National Meteorological Institute of Brazil (INMET). The results indicate the importance of the study relating remote sensing with environmental application in the region of study since population growth, associated with urbanization, brings out as consequences changes in microclimate. For the period 1981-2010 were identified ncreases in temperatures (medium, minimum and maximum) when compared to 1961-1990. Regarding the analyzed administrative regions, the albedo response, the net radiation and the NDVI were significant to detect how much the local environment was influenced, in urban areas the problem of changes in land use and occupation is even greater considering that land waterproofing derived from the substitution of open field areas for buildings and pavement causes great changes in some climatic elements, also, this urban growth permits changes that are oftentimes irreversible. The study indicated a significant association between the reduction of vegetation cover (medium NDVI) and the increase of surface albedo in Brasilia. This can be directly associated with the presence and/or development of heat islands, since there is a positive tendency in the increase of deforestation in Brasilia, consequently, the thermal comfort index demonstrated an increase in 2011 when compared to 1985.