Scope of Work:	GPR survey execution to track the pat5h of leakage in and around Gohar Mahal in Bhopal
Location:	Gauhar Mahal, Bhopal, India
Client:	Cortex Construction Solutions Pvt. Ltd.
Equipment:	GSSI SIR-3000 equipped with 200 MHz and 400 MHz antenna
Challenges:	uncertainity of target location
Summary:	The GPR survey has been carried out at different locations in and around Gauhar Mahal to locate underground leakage in Bhopal. The scope of work includes the mapping of all possible locations suspected to have underground leakage to trace the water flow. The purpose of the project is to prevent the seepage of water on the walls of the Gauhar Mahal by knowing the exact flow of water. Considering the client’s requirements and the expected depth of the leakages, the area has been surveyed using 400 MHz and 200 MHz centre frequency antenna mounted with SIR 3000 GPR system to cover the depth upto 4 m with fair resolution. The data collected from the site has been processed appropriately and interpreted on the basis of the observed features. Among twelve surveyed locations, six locations were found to contain some localized unknown anomaly other than utility. These locations are: parking area, courtyard inside the Mahal, VIP road, Road along the Kolar line, area on the first floor, stage and small room, and inside masjid. Out of these six locations with anomalies are in possible alignment for water flow towards the observed leakage in the mahal due to level difference. The high amplitude reflections at patches at a distance of around 48 m and 100 m from the junction running along the VIP road is might be due to the failure of a joint in a Narmada line the water might be flowing down towards the Gauhar Mahal, through different channels, like, inside the masjid, or the stone steps. The stone steps were found to have higher moisture content, as per information from client end on the basis of electrical resistivity (could not be surveyed using GPR due to inaccessibility for GPR movement). Parking area was also found to have a location of possible leakage. There is a possibility a part of a water flowing down underneath the stone steps flowed in parking area as well. Additionally, the similar high reflections are observed in stage area, small room, courtyard and finally a visible leakage. These all the locations are suspected to be in a alignment for the flow of water. Therefore, it can be concluded that, the water might be leaking from the joint of Narmada line flowing down underneath the stone steps, running inside the mahal to stage area and small room, and then flowing down in courtyard leading to seepage visibility in walls. In addition to these leakage feature observation, a very high reflection has been observed in the area at first floor. This observed high reflection might be due to any void or archaeological artifact. GPR has been efficiently applied for the above mentioned purpose at Bhopal.