Abstract:
Dholavira is one of the five largest Harappan cities located in Khadir Island, district Kachchh, in the state of Gujarat, India. An ancient Harappan city was found there with superbly planned, aesthetic architecture and advanced water management system. A major portion of the city area is unexcavated till today. Therefore, to explore the city more, to decide the excavation strategy of the unexplored areas, it was necessary to conduct non-destructive ground probing survey. Ground Penetrating Radar (GPR) is a non-destructive, geophysical technique, which provides three dimensional image of the subsurface features and depth of such features. Two sites were selected for GPR survey at Dholavira after conducting a through reconnaissance survey to the site. These sites are located at the east of East reservoir and south of Lower Town, respectively. GPR survey was conducted using 200 MHz antenna and GSSI SIR 3000 system. GPR data was processed in conventional software RADAN 7 prior to interpretation. An average velocity of electromagnetic wave in the survey area was estimated as 0.125 m/ns which is later used for time to depth conversion. Low frequency noise and abundance of multiple reflections masked bed rock reflection making the interpretation a challenging task. With appropriate filtering and analysis of data, bed rock profile has been produced of both the surveyed sites. Bed rock in both the sites was found almost flat except some shallow interruptions in the bed rock in Site-1. These interruptions might be produced by nature as no signature of man-made interruptions were noticed. Several linear features were observed in Site-1 and Site-2. Two distinct rubble deposits were observed in Site-1. Archaeological understanding of the observed features has been hypothesized to include existence of water reservoirs, channels, bunds etc in the surveyed areas. GPR survey provided possible features based on interpretation of GPR data but more detailed information about dimension of features was not included in this study due to lack of available techniques.