Effects of changes in use and soil cover on real evapotranspiration from the creation of a remote sensing product in the Xingu basin

Abstract

Several studies have shown that changes in land cover within a given watershed significantly affect the hydrological cycle and its variables. In the Xingu basin, many areas had their vegetation replaced by agricultural crops and pastures, while deforestation has been particularly prevalent in the region known as the Arch of Deforestation. Using remote sensing techniques enable the estimation of biophysical variable ETr for extensive areas, as exemplified in the study basin. Evapotranspiration data used in this work were obtained by creating a product that returns the combined median of the MOD16A2, PML_V2, Terra Climate, GLEAM_v3.3a, FLUXCOM, SSEBop, FLDAS, and ERA5-Land models, with subsequent application of the data provided by Collection 6 of the MapBiomas network, allowing the integration of land use and land cover information with real evapotranspiration estimates for the transition ranges: Forest to Pasture; Forest to Agricultural Land; Cerrado to Pasture; Cerrado to Agricultural Land. The interval defined for the study corresponds to the years 1985 to 2020, according to the historical series available on MapBiomas. After applying programming languages to filter the data, the results underwent statistical analysis to elucidate the effects of soil changes on evapotranspiration. Over the total data period (1985-2020), there was a decrease in forest areas (-16.23%), with conversion to pasture areas, in the order of +12.51%, and agricultural areas, reaching +5.5%. In the same timeframe, evapotranspiration in conversion bands underwent minimal changes, notably from 2009 to 2020, where a decreasing trend was reported of 0.095 mm/month for the “forest to pasture” substitution, and 0.090 mm/month in “Cerrado for pasture”.