GIS and Remote Sensing

Biography

Biography: Vibha Katiyar

Abstract

The area under study lies in a very rugged mountain terrain of Kumaun region is constituted of varied lithogical units of early to late precambrian in age (Auden, 1937) and forms a part of southern extension of Almora crystalline. These two tectonic units Almora Crystalline and Garhwal Group are separated along the North Almora Thrust (NAT). The area is drained by river sarju and Ramganga which have their confluence near Rameshwar. For geomorphic and neotectonic study, contour of the area has been digitized from Survey of India (SOI) toposheet no. 62 C/2 and 62 C/3. The study area is bounded between the latitude 29º 25' to 29º 35' and longitude 80º 05' to 80º 15' and Digital Elevation Model (DEM) has been prepared from these digitized contours of GIS software in ArcGIS 9.3. The DEM shows that the area falls under a rugged mountainous terrain where the height varies between 460 m. to 2489 m. above mean sea level. The prominent peaks of the study area is Thalkedar (2375 m). We used remote sensing data, geological maps, field observations and related structure to map the NAT and lineaments in the study area. Remote sensing is beneficial for recognising fault lineaments in a number of ways (Prost 2001; Babaahmadi et al. 2012). It allows the recognition of geological structures, geomorphic features, rock units, structural lineaments. A Lineaments is a mappable linear or curvilinear features of a surface whose parts align in a straight or slightly curving relationship (Hung, 2005). They may be expression of a faults, joints or other weakness line. Satellite images used in this study are Landsat ETM+ images with composite bands, which are suitable for geological purpose. For better identification of rock units and larger scale faults and lineaments, we merge the images with ERDASS imagine software. This image has a resolution of 30 m which is suitable to detect the lineaments. A total 319 lineaments are identified in which 159 are present in Almora Crystalline and 160 in Garhwal Group tectonic unit. Lineaments have wide variation in their individual length for both the tectonic units in which 0.7 to 0.96 km in Almora Crystalline and 0.46 to 1.16 km in Garhwal Group. The rose diagram also suggests that most of the lineaments in Almora Crystalline are oriented between N30ºE to N60ºE directions while in Garhwal Group the maximum frequency is in NE-SW direction. A rough NE direction of the lineaments of both the tectonic units reveal that most of the lineaments are oriented perpendicular to direction of major fold axis (i.e. NW-SE). However, there is also a marked difference in the density of the lineaments between the two tectonic units. The Almora Crystallines have higher lineament density (1.21 km/km2) than that of the Garhwal Group 0.96 km/km2). This difference in density can be attributed to lithological difference in these two tectonic units.