nd
Session S3.1 - Aqua 2015 - 42
IAH Congress
461 - CONTRIBUTION OF URUCUIA AQUIFER SYSTEM TOWARDS SUSTAINABLE DEVELOPMENT OF
THE SEMIARID REGION OF BRAZIL
Roger Dias Gonçalves
Basin Studies Laboratory, Department of Applied Geology, São Paulo State University, UNESP, Rio Claro, Brazil
Hung Kiang Chang
Basin Studies Laboratory, Department of Applied Geology, São Paulo State University, UNESP, Rio Claro, Brazil
Bruno Zanon Engelbrecht
Basin Studies Laboratory, Department of Applied Geology, São Paulo State University, UNESP, Rio Claro, Brazil
Elias Hideo Teramoto
Basin Studies Laboratory, Department of Applied Geology, São Paulo State University, UNESP, Rio Claro, Brazil
Reiner Stollberg
Groundwater Remediation, Helmholtz-Centre for Environmental Research, Leipzig, Germany
Flávio Paula E Silva
Basin Studies Laboratory, Department of Applied Geology, São Paulo State University, UNESP, Rio Claro, Brazil
The Urucuia Aquifer System (UAS) represents a strategic water resource in the northeastern Brazil. UAS is
responsible for maintaining the low-water flow of the São Francisco River western margin tributaries, providing
water to 13 million people living in the northeast Brazilian semiarid region. The aquifer is composed of Late
Cretaceous sandstones of Urucuia Group (Sanfranciscana Basin), with an average thickness of 155m. UAS
encompasses an area of approximately 130,000 km2 and it overlays on impermeable Precambrian metasediments
of Bambuí Group, forming a table mountain aquifer. In the present work we constructed a groundwater flow
model aiming to evaluate baseflow contribution of the UAS in the Rio Grande River Drainage Basin, located in the
Bahia state. Finite element method was the numerical method used and FEFLOW the computational algorithm. The
simulated area was discretized in a single layer of 27.357,6 km² (314.432 elements), totalizing 4.249,89 km³ in
volume. The terrain topography was obtained by SRTM data and the impermeable base was obtained from water
well logs and vertical electric sounding (VES) profiles. The hydraulic conductivity values employed in the
simulation varied from 1x10-5 m/s to 5x10-4 m/s and those of recharge rates varied from 20% to 25% of average
rainfall precipitation. The results of the steady state model confirmed the fairly homogeneous nature of the aquifer
with an outflow of 23,718,654 m³/day. Further simulations incorporating basement leakage better reproduced the
decreasing flow rates observed in the river basin.
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