Limits and conditions for the exploitation of alluvial aquifers in the Brazilian semi-arid region

Easily exploitable aquifers are formed along river beds in the Brazilian semi-arid region and present characteristics that enable the construction of underground dams. The estimate of the potential effective exploitation of these aquifers must take into account the pumping limits of the wells, the upstream groundwater inflows and the flows to downstream reaches and through the underground dam, whose reduction influences the downstream supply. The current research presents a real case study about an aquifer reach, with underground dam and wells, which was analyzed through computational model. We simulated the groundwater flow patterns according to different exploitation scenarios and found that there should be water extraction limitations to assure the required downstream flows. The limitations can be minimized through appropriate well locations and exploitation regimes, as well as through the implementation of underground dams. The definition of these measures becomes possible through the sound use of computational simulation, but their effective implementation will depend on negotiations among users at the basin scale, so that appropriate water permits can be issued.