Aquifer systems of the central-north portion of the Sanfranciscana Basin and regional flow estimate

• Main Authors: Flavio de Paula e Silva, Hung Kiang Chang
• Format: Article
• Language: English
• Published: Associação Brasileira de Águas Subterrâneas 2018-07-01
• Series: Revista Águas Subterrâneas
• Subjects: Aquífero Urucuia. Aquíferos permo-triassicos. Fluxos locais. Fluxo regional. Hidroestratigrafia
• Online Access: https://aguassubterraneas.abas.org/asubterraneas/article/view/29125

Urucuia Aquifer System (UAS) lies in the north-central portion of the Sanfranciscana Basin and it occupies an area of approximately 125,000 km². UAS is responsible for sustaining the baseflow of the left margin tributaries of the São Francisco River Basin. Recently, subsurface studies have identified underlying permo-triassic aquifers, which have been previously considered as part of the Urucuia Aquifer System. These aquifers are attributed to belong to Sambaíba and Motuca formations of the Parnaíba Basin. Local groundwater flow systems, characterized by discharging along the adjacent recharge areas, shows a predominantly east flow direction,  contributing  991 m³/s to the baseflow of the São Francisco, Tocantins and Parnaíba River basins.  The regional NW flow system, parallel to the longitudinal axis of the Sanfranciscana Basin, discharges 29 m³/s of groundwater of the permo-triassic aquifers to the Tocantins River Basin. The groundwater withdrawal by deep wells producing from the permo-triassic reservoirs is likely to affect the baseflow of the Tocantins State Rivers. Given the hydrogeological peculiarities observed, the current models of the Sanfranciscana Basin water resources management need to be reassessed.