An approach to estimate porosity and groundwater salinity by combined application of GPR and VES: a case study in the Nubian sandstone aquifer

摘要

Ground-penetrating radar signal propagation is strongly controlled by water content. Therefore, it can be employed to address numerous hydrogeological problems, ranging from geological structures to petrophysical properties. In the present study, ground-penetrating radar and vertical electric sounding measured data are analysed and combined to answer the most hydrogeologically simple and geophysically complex question of groundwater salinity. Geophysical logging, in particular resistivity logs were used to correct the static shift's usual effect on vertical electric soundings (VES), as well as to correlate with surface data. The dielectric constant of the water bearing horizon was estimated through ground-penetrating radar data interpretation, which in turn plays an important role in the "estimation of the volumetric water content. On the other hand, vertical electrical sounding was used to estimate water saturation. Combining the results obtained from both methods, the groundwater salinity of a shallow aquifer, mostly clay-free, can be estimated. The method is applied to a data set measured over a sand aquifer in the Aswan area, Egypt. The results obtained indicated that the present technique is efficient, since the estimated groundwater salinity using this technique is about 1152 mg/I, whereas the groundwater salinity estimated from water sample analysis is about 950 mg/l.