APPLICATION OF GEOMATICS IN STUDY OF SUBSIDENCE IN MINING AREAS

Abstract

Subsidence is basically sinking of the ground and if the occurrence is due to mining activities, then the subsidence is known as mine subsidence. People are measuring subsidence from last 50 years but with the time, methods are changing. From the last 15-20 years, it is improving rapidly as satellite data are available. So the need for ground survey has become limited as it could be done remotely and be compared with the existing ground survey for accuracy assessment. Nowadays InSAR and DInSAR techniques are used, which have centimetric and milimetric accuracy in land deformation measurements. In this thesis, mine subsidence is tried to be identified and measured using the DInSAR technique from the Sentinel-1 data sets. For this Sentinel-1 SLC data sets of different dates are downloaded and processed. First of all, each data pair is coregistered, followed by Interferogram generation. After that topographical phase removal and unwrapping is done, and finally, conversion of phase into heights for the displacement Computation takes place. The results are compared to the ground data collected by the DGPS survey from the study area. In this study, subsidence value is obtained approximately 1 mm per day for all the points in all the data sets from InSAR software (SNAP) processing. After comparison, it can be seen that subsidence obtained from the ground survey and SNAP software are similar in manner. The relationship in both the values has been observed as having polynomial pattern.