GEOMORPHOLOGY, TERRACES OF VARIOUS DOMINE OF ALAKNANDA ITS TRIBUTARIES AND NEOTECTONISAM, GARHWAL HIMALAYA PARTS OF CHAMOLI TEHRI UTTAKASHI & PAURI UTTAR PRADESH (UTTRARKHAND) INDIA
Authors:   Ex. Director Geological Survey of India, Ex. Director Rajeeve Gandhi Prodyogiki Mahavidhyalaya Bhoplal M.P. India., Khan A. A. , Chaterjee A.C ,   Ex Head of Departmant School of Studies in Geology Vikram University Ujjain M.P. India.
Published: June 2023

The Geological and Geomorphological study in Upper Ganga basin has been attempted in parts of de Uttarkashi,Chamoli, Pauri and Tehri districts, an area of 10000 Sq.kms in parts of QA sheet 53J and 53 N on 1:50000 scale of Garhwal Himalaya U.P has been covered presently known as Uttrakhand State of Union of India. Out of total area of study, an area about 3500 sq.Kms (1:50000 scale) has been selected for detailed Geological, Geomorphological and Sedimentological study. The area of Upper Ganga basin consisting of Alaknanda, Bhagirathi, Bhilangna, Nandakini, Mandakini, Pindar, Dhauli- Ganga Bal- Ganga, Madhmeshwar Ganga and Berhi Ganga. The Alaknanda is chracterised by six terraces followed by Bhagirathi with five terraces, Bhilangna Nandakini four terraces, Mandakini /Pindar/Dhauli-Ganga /Balganga three terraces, Madhmshwar Ganga two terraces and Berhi Ganga one terrace, amidst these Alaknanda is trunk stream and others are tributaries. Geomorphologically, the area is divided in to seven geomorphic units viz High relief formerly glaciated area, Structural hills, Denudational hills, Area of mass wasting, High level dissected fans River Terraces and Present day flood plain of Alaknanda and its tributaries. These units area developed in response to lithology to erosional land depositional activities and tectonic in which they are embedded. Each unit is characterized by distinct drainage, diagnostic geomorphic landform elements and features, photo charcters and morphogenetic expression. The other geomorphic features and elements identified in the area are point bar, channel bar, alluvial fans ,talus cone , rock cut terraces fan cut terraces , abandoned and fossil channel courses,epigenetic gorges, strant lines landslides, rock fall scree and scree slope, retreating scarp, abandoned cirque, cirque morines, arÃƒÂªtes, threshold, horn peak and glacial lake. The area genetically comprised of terraces of three domains, viz. glacial, fluvio-glacia and fluvial which represent distinct environment of sedimentation of Pleistocene, late Pleistocene and Holocene time during Quaternary period. The glacial terraces are identified at an average elevation of 1150 m above m.s.l. the fluvio-glacial terraces at an average elevation of 975 m above m.s.l. and fluvial terraces at an average elevation between 650 to 900 m above m.s.l. The Badrinath temple is situated in glaciated trough valley of Alaknanda, which comprise of, four levels of the glacial terraces (lateral moraine), cirque moraine on mountain flanks and the terminal moraine at the base of valley. whereas Kedarnath in the upstream of Mandakini, where number of well developed cirques were identified on high mountain, they are mostly arm chair shaped hollows with a steep to vertical head walls, concave floor and a threshold, these cirques are noticed at an average height of about 4500 m. The Kedarnath temple is situated in glaciated trough valley on quaternary platform formed by coalescing of cirque, lateral moraine and terminal moraine. The-Himalayan thrust like Central thrust Srinagar thrust, Alaknanda fault, Tons thrust show flattening dip suggesting that they lie at comparatively at shallow depth at short distance, down dip from their out crops, recent movements along the trace of these thrust/ faults are not of high and longer magnitude but have considerably affected Quaternary terraces of glacial, fluvio-glacial and fluvial domain of Alaknanda and its tributaries. Beside drainage, river bed profile, landscape architect and over all morphogenetic expression of the area, this bears the adverse impact of tectonic activity. The imprints of neotectonisam associated in the area indicate that these thrust /faults are active and have, signatures of sinking of landscape, mass wasting activities and posed neosiemic hazards and tectano-ecological problems, bears signatures of sinking of the area, mass wasting activities and neosiemic hazards. The geomophological study of the area, overall morphogenetic illustration, imprints of neotectonisam, disposition of terrces of different domains, mass wasting activities, drainage net, channel morphology, landform elements of glacial, fluvioglacial and fluvial domain of Alaknanda and its tributaries indicate that tectonically the area is active and slow movements are taking plae along thrust, faults and lineament. In the area North of Wazri in Jamuna valley, North of Uttarkashi around Sainj in Bhagirathi valley, around Tugnath and Chamoli and South of Joshimuth in Alaknanda valley revealed that there is sharp persistent curvilinear break in topography, which has geothermal manifestation at Wazri Gagnani anda Tugnath in the form of emitation of hot springs. This curvilinear line has further reconfigurated the neo stream net works system and affected morphogenetic expression it appears to be due to horizontal movement of sub - tectonic plate towards south, which, is sole collective and cumulative causative factor in dislocation of tectonic ecology of the area and has resulted micro earthquake shocksand and segmental sinkiking of area. The overall study revealed that the the area is sensitive active and is vulnerable to any techtono- seismic event it is matter of serious concerned and needs further attention.