Ground-Penetrating Radar Application for ‘Water in İstanbul’ Project

Abstract

‘Water in Istanbul: Rising to the Challenge?’ is the title of a new 24-month project which brings archaeologists, historians, engineers, and urban scientists together to explore the historical water management infrastructure and evolution of water technology in the city of Istanbul through history. One of the outcomes of this research will be producing a hydraulic model that will help us to understand how the past system functioned and was managed. This in-depth research also hopes to bring a new perspective for the contemporary water-related challenges. The archaeological field work geographically focuses on the I. Hill of the Byzantine city where Ottoman imperial palace called Topkapı gets located over. This is the most challenging topographical area regarding the historical water distribution which functioned according to the principle of gravity. Non-destructive survey methods are crucial in such fragile archaeological areas. Also, the bureaucratical difficulties related to the legal permissions make it a necessity to apply archaeogeophysical methods. In the first field work phase, we preferred ground-penetrating radar (GPR) in order to identify the remains, including supply lines providing freshwater to the Topkapı area. Our survey based on previous research by Hülya Tezcan and the archaeological survey results of Çiğdem Özkan Aygün in order to identify the areas for investigation with GPR. Thanks to GPR, the location, geometry, and depth of the buried historical structures would be possible to determine. GPR, which provides high-resolution information from shallow areas, is a geophysical method frequently used, especially in archaeogeophysical studies. The method is based on recording the travel times of reflected and scattered electromagnetic waves, which are sent to the subsurface with high-frequency antennas, with a receiver. In this study, results of the GPR study, which was carried out using a 350 MHz centre antenna frequency to detect the historical water channels beneath the area surrounding the Topkapı Palace are mentioned. After processing the data sensitively, GPR sections were interpreted and all possible water channels were detected. Depths of the detected channels are between 2 and 5 m below the surface.