Dinâmica do uso e cobertura do solo e evolução das demandas consuntivas d’água e seus impactos nas vazões da bacia hidrográfica do rio São Francisco

Abstract

This study sought to assess the evolution of Land Use and Coverage (LUC) and consumptive demands for water and the impacts of these evolutions on the water resources of the São Francisco River Basin (SFRB). The LUC for the SFRB was obtained from the MAPBIOMAS platform, having been evaluated spatially and in terms of the variation of its percentage area for the year 1985 and 2019. The consumptive demands for human, irrigation and industrial uses were determined based on the flows withdrawn for consumptive uses of the Brazilian counties of the Brazilian National Water Agency (ANA), being determined for the Sobradinho, Itaparica and Três Marias reservoirs in the period of 1961 until 2017. Precipitation and flow data were obtained from ANA's HIDROWEB database for the period from 1985 to 2015, evaluating the existence and magnitude of the trend of the stations contained in the SFRB. The results pointed to a large and accelerated expansion of agriculture in the SFRB, highlighting the Western of Middle São Francisco (WMSF). The trend analysis showed an absence of trend in most pluviometric stations and the presence of strong decreasing trends in fluviometric stations, especially those located in the WMSF. This divergence in precipitation and flow trends indicate that the flow reduction may not be linked to a reduction in precipitation, suggesting other mechanisms responsible for this decrease, such as the anthropic modifications of the LUC and the increase in flows removed for consumptive uses.