Integrated geophysical investigations to reconstruct the archaeological features in the episcopal district of Side (Antalya, Southern Turkey)

Electrical resistivity tomography (ERT) and ground-penetrating radar (GPR) are frequently used geophysical methods in the exploration of near-surface targets such as archaeological features. These methods were therefore applied to investigate a wide area in the Side ancient city located nearby the Manavgat district of Antalya, Turkey. The main purpose of the geophysical survey was to answer several questions about the design or usage of a huge area located nearby the episcopal residence of Side that belongs to the late antique/early Byzantine times (5th/6th century A.D.). The investigation area is thought to be the garden (hortus) of the residence. The survey site covering an area of approximately 6000m2 was investigated in detail by two geophysical survey campaigns carried out in 2016 and 2017. During the two survey campaigns, 102 ERT and 127 GPR lines were measured. ERT data were collected by dipole-dipole electrode array, and a 500 MHz shielded antenna was used to measure the GPR data. By evaluating both data sets with appropriate processing steps, 3D geophysical models of the survey area were produced. These models provided obvious traces of buried anthropogenic structures, characterized by relatively high resistivity and high EM wave reflection amplitude. The identified structures lay on the NS-EW axis, which is consistent with the major layout of the city; however, they do not correctly align with the late period structures currently standing on the ground. Therefore, it is interpreted that these buildings belong to a predecessor period (i.e. Roman Imperial Period). Further information such as the purpose of the use of these buildings can only be revealed by an archaeological excavation.