Remote sensing and GIS technologies for improvements in geological structures interpretation and mapping

In a highly rugged terrain like the Himalayas, due to accessibility problems, conventional field-based geological mapping is a Herculean task. Rock exposures and geological structures are often studied only at a few places and later interpolations between observations are made to acquire continuity of geological formations and structures. With the advent of satellite images having synoptic view, higher spatial and better spectral resolution, it has become possible to recognize deformation structures having tectonic significance in a better and more reliable way. Hitherto, the minor structural changes could not be realized on ground mapping, which has always a limited coverage. This limitation acted as Ill hindrance to recognize tectonic significance of the structural features. An integrated approach of remote sensing and Geographic Information System (GIS) technologies provides better opportunities to prepare geological maps with higher accuracy and in a cost-effective manner. Using relatively high resolution multispectral digital data, interpretation of field observations can be done very efficiently without any vague interpolation between observations. Further, an integrated approach of remote sensing and GIS can be employed to make improvements in existing geological maps. Such an integrated approach becomes complementary to conventional field-based geological mapping techniques. In the present study, an integrated remote sensing and GIS-based approach has been developed and successfully demonstrated to make improvements in existing geological maps and result in better identification and interpretation of geological structures. The study has led to the modification of existing maps of Nahan Salient, Himachal Pradesh, India, after proper field verifications.