Characterization of Soil and Rock Hosting an Aquifer in Southeast Panama City using Geotechnical, Geophysical and Geochemical Parameters

Abstract The aim of the present study is to assess the combined use of geotechnical and electrical geophysical methods to determine water quality and rocks mechanics in an aquifer. The aquifer studied is located in the Tocumen sector of Panamá City, located to the southeast of city, where there is a need to study the possible use of this aquifer to provide drinking and/or irrigation water based on its quality. To this end, a 10 m well was perforated and sampled to characterize the host soil and rock trough granulometry, determine the Atterberg limits, measure the physicochemical parameters and perform a chemical analysis, including reactivity (pH), electrical conductivity (EC), organic matter content, cation exchange capacity, calcium carbonate, sulfates, chlorides, SiO2, Al2O3, Fe2O3, CaO, MgO, SO3, Na2O and K2O. In addition, a 2D electrical resistivity tomography profile was conducted in order to correlate the electric parameters with the physicochemical and chemical ones and extend them laterally to check the continuity of the characteristics measured. The results show a good correlation between geotechnical, geophysical and chemical parameters, thus highlighting the presence of discontinuities that must be overcome by infiltrated rainwater to reach the deepest levels, which are characterized by the presence of water. The water chemistry varies with depth, with sodium bicarbonated water being the predominant facies.