Hydrogeological and numerical criteria for groundwater withdrawal permission in the Marizal-São Sebastião Aquifer, State of Bahia, Brazil

Abstract

Groundwater is part of the water supply for industrial use in the Camaçari Industrial Complex (CIC) (Bahia, 2016). Managers from the CIC developed a computational model to evaluate exploitation of groundwater, the Regional Numerical Flow Model (RNFM), which has the function of calculating groundwater volumes for withdrawal in order to choose the best location for the pumping wells and to establish the aquifer hydrological equilibrium during the regime of groundwater withdrawal. In addition to the current management this work proposes hydrogeological criteria for granting groundwater withdrawal permission from the Marizal-São Sebastião aquifer system in the CIC region. To introduce the hydrogeological criteria, this work developed a new water zoning for the aquifer; calculated the water reserves and potentials for each zone; and classified the water zones in terms of the degree of exploitation favorability. To confirm the adequacy of the proposed criteria, this work reevaluated a previous permission process in the region (11 pumping wells), for which the NRFM established the well locations and the groundwater volumes to explore. This work verified that using only the NRFM, which is the current management tool for granting groundwater withdrawal licenses in the CIC region, is not conservative enough for sustainable groundwater withdrawal in each water zone. Using the combination of hydrogeological and numerical methodologies for the pumping wells would result in a better choice for well locations in water zones with larger groundwater potential and favorability, thus promoting a sustainable groundwater exploitation.