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

Abstract

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/l, whereas the groundwater salinity estimated from water sample analysis is about 950 mg/l.

Influences on the resolution of GPR velocity analyses and a Monte Carlo simulation for establishing velocity precision

“…This paper explores the precision with which GPR velocity can be measured from single CMP gathers. Whilst we acknowledge that PSDM methods overcome many factors that limit the accuracy of CMP-based velocity analysis (e.g., Bradford and Sawyer 2002), the acquisition of multi-offset data and the implementation of this costly migration procedure are beyond the resources of many practitioners and the use of single CMP gathers remains commonplace (e.g., Jacob et al 2010;Khalil et al 2010;Steelman and Endres 2010). CMP gathers therefore represent familiar territory for the illustration of the influences on velocity resolution that, in any case, are present in the velocity analyses that must be performed to facilitate PSDM.…”

“…; Khalil et al . ; Steelman and Endres 2010). CMP gathers therefore represent familiar territory for the illustration of the influences on velocity resolution that, in any case, are present in the velocity analyses that must be performed to facilitate PSDM.…”

Current uses of ground penetrating radar in groundwater-dependent ecosystems research

“…Airborne frequency and time-domain electromagnetic techniques have been used to delineate freshwater-saltwater interfaces (Wiederhold et al, 2009). A combination of vertical electric soundings and ground penetrating radar (Khalil et al, 2010) has been implemented to infer 2D near-surface aquifer porosity and groundwater salinity. Resistivity and seismic refraction profiles have been combined to determine 2D near-surface porosity, water saturation, and volumetric water content (Mota and Monteiro dos Santos, 2006;Langston et al, 2011).…”

Distinguishing Capillary Fringe Reflection in a GPR Profile for Precise Water Table Depth Estimation in a Boreal Podzolic Soil Field

“…The water table reflects more than 40% of GPR wave energy in coarse-grained soils [42]. Accordingly, the water table can give continuous and mostly flat reflections with high amplitude in GPR radargrams [30,[43][44][45][46][47][48]. Based on this advantage, GPR is instrumental and an essential method in shallow groundwater studies [15,49].…”