G. Philip

Channel migration studies in the middle Ganga basin, India, using remote sensing data

Abstract An area in the middle Ganga basin lying around Monghyr, Bihar, India, has been selected for channel migration investigations, using mainly remote sensing data. Changes in planform of the rivers over approximately 50 years have been evaluated and the palaeocourses of the Ganga and Burhi Gandak rivers have been reconstructed using the disposition and pattern of, among other things, oxbow lakes, meander scars and abandoned channels. It is inferred that the Ganga and the Burhi Gandak rivers moved from north to south by 20 km and 30 km respectively. The study demonstrates the utility of remote sensing data in such channel migration investigations.

Landsat Thematic Mapper data analysis for Quaternary tectonics in parts of the Doon valley, NW Himalaya, India

Abstract Identification of active faults in Himalaya is extremely significant as they directly reflect the Himalayan continental collision. They have moved repeatedly during the Quaternary, resulting in the dislocation of many landforms, such as streams, alluvial and piedmont fans and river terraces, etc. In the present study, Landsat Thematic Mapper (TM) data has been used to identify signatures of Quaternary tectonics in parts of the Doon valley, NW Himalaya. The Siwalik zone is being squeezed between the very active Main Boundary Thrust and the Himalayan Frontal Thrust and there is differential uplift and subsidence in the Doon valley. The study has helped to extract certain subtle geological information which has played a significant role in the present geomorphic configuration of the valley. Apart from the many lineaments identified it was observed that a NNE-SSW trending lineament, identified distinctly on the satellite image, separates the Doon valley fan sequence from the Yamuna terraces in the we...

Neotectonic activity in the Markanda and Bata river basins, Himachal Pradesh, NW Himalaya: A morphotectonic approach

In an orogenic belt like the Himalaya, expressions of neotectonic activities are numerous, manifested mainly by faulting and tilting of Quaternary deposits (alluvial fans and river terraces), fault controlled channels, river capture, etc., well‐expressed on satellite images. Studies on quantification of block tilting of river basins in the Himalaya have not been attempted so far. The aim of the present communication, therefore, is to quantify block tilting using morphotectonic parameters, such as basin asymmetry factor (AF) and transverse topographic symmetry factor (TF) in the uppermost courses of the Markanda and Bata rivers (Himachal Pradesh). The AF values of 89.34 and 25.69 and the TF values of 0.77 and 0.67 due south‐southwest respectively for Markanda and Bata indicate that the northern segments of the Markanda and Bata river catchments are tilted south with respect to the trunk streams. Fault and lineament controlled channels of the Bata and Markanda rivers and some of their tributaries further corroborate the neotectonic activities in this region.

Geomorphic signatures of active tectonics in the Trans-Yamuna segment of the western Doon valley, northwest Himalaya, India

Abstract Being involved in the late orogenic movements of the sub-Himalaya, the Doon valley and its Quaternary formations have received considerable attention from Earth scientists in the study of active tectonics and paleoseismic events. Study of aerial photographs and satellite data, and selected field checks not only confirmed neotectonic features already reported by various authors but also revealed the presence of more such features. In response to active tectonics, these features have affected very young terraces and Quaternary sediments in the Trans-Yamuna segment of the Doon valley in the western sub-Himalaya. In the present study, an attempt has been made to understand the neotectonic implications of these movements on landforms in and around Sataun-Sirmuri Tal. Ground evidence indicates that the area has experienced at least three major tectonic impulses since the generation of the Main Boundary Thrust. The major tectonic disturbances are most likely due to co-seismic activity along the ongoing Himalayan tectonic processes. In this paper, we discuss some of the strong geomorphic signatures, such as lineament and active fault traces, pressure ridges, sag ponds, alluvial fans, river terraces and finally landslides, which are indicative of active tectonics in this area. On the basis of the present-day geomorphic configuration of this sub-Himalayan basin, a possible evolutionary history is also presented.

Mapping the Nidar Ophiolite Complex of the Indus Suture Zone, Northwestern-Trans Himalaya using IRS-1C/1D data

In this study, using high resolution IRS-1C/lD satellite sensor data, the digital terrain model (DTM) of the Nidar Ophiolite Complex, Indus Suture Zone, India provided an excellent three-dimensional perspective of the terrain and helped in a comprehensive appraisal of the lithology and structure and their influence on the development of the present-day landforms of the cold and dry high-altitude region of the Trans-Himalayan terrain. While the earlier published geological maps of the area show the presence of a number of lithological units, this study has demonstrated that refined and systematic lithological boundaries and structural inferences can be made from the high resolution Indian Remote Sensing Satellite sensor data.

Glacial mapping using landsat thematic mapper data: A case study in parts of gangotri glacier, NW himalaya

Glacial mapping is difficult and hazardous because of the remoteness and inaccessibility of the terrain. In this context, remotely-sensed data from satellites provide valuable information on glaciers and the associated landforms. It is important to note that judicious selection of spectral bands is critical in mapping the glacial features. Glacial landforms in parts of Gangotri glacier, NW Himalaya, have been delineated using selected bands of Landsat Thematic Mapper Data. Digital image processing of Landsat data has helped in identifying the major features of the Gangotri glacier such as accumulation and ablation zones, and glacial moraines. The study shows that Thematic Mapper bands 4, 5 and 7 are more useful in snow mapping because of their distinct spectral discriminability in identifying the glacial features.

Shrinking lake basins in the proximity of the Indus Suture Zone of northwestern Himalaya : a case study of Tso Kar and Startsapuk Tso, using 1RS-1C data

Abstract The study of active tectonics in Himalaya is important as this helps to understand the style of evolutionary process of this gigantic mountain system in more specific terms. The formation of lakes, regarded as the crown stage development of an orogenic belt, is an impressive geomorphic feature that adorns the Himalayan belt end to end. Tso Kar and Startsapuk Tso are the two ancient lakes that lie south of the Indus Suture Zone in the northwestern Himalaya. An attempt has been made to map the former extent of these lakes, using remote sensing techniques, for providing vital clues in elucidating the paleoenvironmental conditions under which these water bodies were developed. It is observed that the dimension of these lakes has constantly fluctuated in time due to ongoing compression in the collision regime and possible climatic influences that have been recorded on a large scale globally. An added advantage of this study has been to evaluate the high spatial resolution data of the Indian Remote Sensing Satellite (IRS-1C) for geomorphological, lithological and structural inferences in the arid, inaccessible and complex terrain like the northwestern Trans Himalaya.

Geomorphic evolution of a part of Middle Ganga Plain, Bihar: A case study using remote sensing data

An insight into the geomorphic evolution of any area can be obtained by detailed landform mapping. In the present study, an area in the Middle Ganga Plain has been selected for the study using mainly remote sensing data. Various fluvial landforms have been mapped and the changes in planform of rivers over approximately 50 years have been evaluated. Both fluvial processes and tectonic activities are considered to have collectively influenced the migration of the rivers in this region. Digital enhancements of Landsat MSS and TM data are found to be quite useful in identification and mapping of subtle fluvial palaeofeatures. The present study demonstrates the utility of remote sensing in examining the geomorphic evolution of the area.