Integration of 2D/3D ground penetrating radar and electrical resistivity tomography surveys as enhanced imaging of archaeological ruins: A case study in San El‐Hager (Tanis) site, northeastern Nile Delta, Egypt

Abstract

AbstractIn archaeo‐geophysical investigations, the accuracy and resolution of the generated geophysical models are crucial parameters for excavation decision. Therefore, the combined use of different geophysical data sets is necessary to improve the interpretability of archaeological ruins, particularly in case of low physical contrast objects. The present study's objective is to validate the outputs of integrated ground penetrating radar (GPR) and electrical resistivity tomography (ERT) surveys in Tanis, which is considered one of the most important archaeological sites in the Nile Delta, Egypt. The GPR survey was carried out along an area of 24 × 31.5 m with profile interval of 0.5 m in two orthogonal directions using 100, 200 and 600 MHz shielded antenna. Moreover, nine ERT profiles were performed along the same GPR lines for comparison and integration using Wenner‐beta (WB) and dipole–dipole (DD) arrays with 1 m electrode spacing and 3 m profile spacing. In addition, the ERT measurements were executed by implementing two tie lines of the same length, electrode spacing and electrode arrays to reduce the effect of banding or directional bias. The processed 2D GPR and ERT profiles have illustrated series of mud‐brick walls within the top 2 m in silt–clay background which is underlined by the turtle‐back of Sand Island. In such conditions, the mud‐brick walls in conductive soils with complex spatial distributions have produced tricky and difficult anomalies to be interpreted using only 2D data sets. To overcome this challenging case, the GPR orthogonal profiles were collated in 3D domain, while the ERT profiles were gathered and inverted using 3D robust inversion algorithm and validated with an identified mud‐brick wall. Therefore, the created 3D visualizations demonstrated the efficiency of the joint use of the ERT and GPR surveys as an enhanced mapping tool for buried archaeological ruins and can be used at similar archaeological sites all over the world.