Integration of DInSAR Technique and Conventional Methods through GIS for Verification of Quantified Surface Changes

Any underground excavation or depletion of either solid minerals or liquids may lead to deformation of the surface profile for areas present above these underground zones. The awareness of deformation rate or rate of change of the natural surface is very important for proper planning and utilization of the geo-resources. These often suffer from the limitations of proper methods of data capture in such areas, accessible or in-accessible to the human beings; in terms of the data density, the time involved in the data capturing process and the associated risks in doing so. Once a proper data is captured, it may easily be used to generate the models of the geo-structures present in and around the region of interest. Till date, the conventional methods of surveying, like precise leveling or GPS, were used for the data capture, which are point observations and suffer from disadvantages like limited spatial resolution, large data capture time, easy manipulability of the collected data, high risk for the operators involved, high cost for large areas etc. With the advent of newer and advanced techniques of data capture in geo-information; use of high precision satellite imagery, especially the synthetic aperture radar (SAR) data having the complex information (i.e. the phase as well as amplitude), has been found to provide adequate data for such purposes. Interferometric synthetic aperture radar (InSAR) is a technique used to reconstruct the digital elevation models (DEM) of the observed scenes. Determination of the surface deformation profiles, integrating the surface displacements using the GIS tool (GRASS) and verification of the surface displacement rates become the main objectives of the present paper. It has been observed that the values of the displacement rates computed using the new method match closely with those obtained using the conventional methods of surface data capture techniques. It has also been found that the new method has several advantages over the conventional methods, as discussed later in this paper.