Evolution of Urucuia Aquifer System contribution to São Francisco river, Brazil

Abstract

The Urucuia Aquifer System (UAS) is the most important aquifer located in the São Francisco river watershed, with high productivity, maintains large irrigated areas and represents about 41% of the basin’s groundwater resources. Its baseflow is responsible for the maintenance of São Francisco low flow regimes, for this reason it’s important to have a correct understanding about the baseflow variations in time. This work aims to analyze the variation of the Urucuia contribution in all São Francisco catchments using local minimum method of hydrographs separation in 45 gauge stations. The baseflow average is about 200 mm/year (570 m³/s). Among the last century cycles, the most notable and extensive one had its peak in 1980 with 280 mm/year (792 m³/s) of contribution to São Francisco river. Since then, it presents a continuous decreasing pattern, reaching in 49% (390 m³/s). Regardless of the causes of declining (natural or human-induced), measures must be taken to ensure sustainable water usage, since the systematic decreasing of potable water leads to extensive socio-economic stresses.

Keywords

• Fluxo de base. Separação de hidrogramas. Gestão de Recursos Hídricos.