Influência do uso e ocupação do solo na evapotranspiração utilizando técnicas de sensoriamento remoto para a bacia do Xingu

Abstract

Changes in the use and land cover of a watershed have significant impacts on hydrological processes and water balance variables, such as real evapotranspiration (ETr), a component of the hydrological cycle evaluated as one of the most affected by changes in the type of watershed cover. surface. Allied to the fact, the technique of remote sensing has become an excellent tool for assessing environmental degradation, as it allows analyzing the changes caused by anthropic action in temporal and spatial scales in complex environments of hydrographic basins. In this context, focused on the Xingu Hydrographic Basin, and its five sub-basins (Lower Xingu, Middle Xingu, Upper Xingu, Iriri and Nascentes do Xingu), the present work aimed to: evaluate the performance of seven ETr products (FLDAS , MOD16A2, PML_V2, TerraClimate, ERA5-Land, GLEAM_v3.3a and SSEBop) and the upscaling of FLUXCOM, compared to the median of the eight models in the common period from 2003 to 2014; to study the influence of changes in land use and land cover on the ETr, estimated by the product created through the median of the eight models, relating it to the data from MapBiomas, in the available interval of 1985-2020; and to analyze the effects on real evapotranspiration arising before (1993-2015) and after (2016-2020) the filling of the reservoir of the Belo Monte Hydroelectric Power Plant, through the SSEBop BR Evapotranspiration application, which uses images from the Landsat 5, 7 and 8 series TOA reflectance in obtaining the ETr. All datasets described were accessed and processed through the Google Earth Engine platform. For most analyses, the results found suggested that the products MOD16A2 and GLEAM_v3.3a returned data closer to the median of the models, with convergence of evapotranspiration values around 93.5% and 91.7%, respectively; decrease in forest areas (-16.23%), with conversion to pasture areas, in the order of +12.51%, and agricultural areas, reaching +5.5%, with the maximum peak of ET during the season conversion (October-November); and two trends in the average ETr related to the construction of the Belo Monte HPP, with a downward trend of 0.066 mm/d in the period prior to the reservoir (1993-2015), and an upward trend after its filling (2016-2020) equal to 0.040 mm /d.