This paper describes the successful application of an integrated geophysical survey to investigate the depth of
underground water table and the location of probable cavity occurrences at a developing residential area to
design the foundation of under constructing urban buildings located at Hesarak-Karaj, Alborz province of Iran.
The integrated shallow and non-invasive geophysical survey consists of Electrical Resistivity Tomography
(ERT) and Ground Penetrating Radar (GPR). These methods could appropriately indicate the existence of the
water table at a depth of approximately 12 m while processed GPR radargrams localized no cavity occurrences
in the studied site. A 100-MHz shielded GPR antenna has been used to conduct a high resolution shallow subsurface
survey in order to delineate probable cavities of the area, and two electrical arrays of gradient and Wenner
have been used as well to image resistivity variations of subsurface layers especially for prospecting water saturated
zone. The acquired results which were in good accordance with the reality of the studied area at locating
water table and cavity occurrences could effectively provide guidance to builders in order to tackle water flow
issue and not to concern about filling cavities during constructing any building in the site.