Delineating groundwater flow-paths in fractured aquifers under hazardous environment using conceptual and geophysical modeling with a case study

Abstract Construction of landfills and open dumping of solid-waste above fracture-controlled aquifers can increase leachate concentrations, contaminating useable surface and shallow groundwater resources. In such cases, it is essential to define the hydrogeological processes and identify the pathways in the fractured aquifer system for contamination migration near the dumpsite. Abu Zaabal Quarry is a typical example where a solid-waste dumpsite was installed directly on fractured basalt around polluted groundwater ponds. To assess the vulnerability conditions in this complex environment, Seismic Refraction Imaging (SRI) and Electrical Resistivity Tomography (ERT) were integrated with the available geological and hydrogeological information for delineating the effective fractured zones and to refine the site conceptual model of the potential pathways associated with solid waste leachates, The constructed resistivity and seismic images help to identify interflow zones in the basaltic protective zone and provide valuable information about the orientation and location of fractures feeding the ponds underneath the dumpsite. The presence of NW vertical fractures, which could provide a vertical hydraulic connection with the lower aquifer, allows the percolation of the leachate in the area around the dumpsite. These results show the advantage of using a combination of various geophysical methods for delineating the strikes of the prevailing fracture patterns and clarifying the pollution situation at typical composite landfills worldwide. The proposed conceptual groundwater flow model is critical for understanding hydrogeological and transport processes in such hazardous environments to achieve sustainable management of groundwater resources.