EVOLUTION OF FLUVIAL TERRACES OF ALAKNANDA AND ITS TRIBUTARIES AND IMPRINTS OF NEOTECTONISAM IN UPPER GANGA BASIN, GARHWAL HIMALAYA, PARTS OF CHAMOLI TEHRI UTTAKASHI & PAURI DISTRICT UTTAR PRADESH (UTTRARKHAND) INDIA
Authors:   Ex. Director Geological Survey of India., A.Khan A. ,   Ex. Director Rajeev Gandhi Produyogiki Mahavidhaylaya., Chaterjee A.C ,   Ex HOD, School of Studies in Geology.,   Vikram University Ujjain (M.P.) India.
Published: February 2023

The Geomorphological study in in Alaknanda and its tributaries Ganga basin Garhwal Himalya parts of Chamoli Tehri Uttarkashiand Pauri district Uttar Pradesh (Uttrarkhand with special reference to fluvial terraces has been studied . An area about 10000 Sq.kms in parts of QA sheet 53Jand 53 N on 1:1000000/ 1:50000 scale of has been covered. The area of Upper Ganga basin genetically comprised of terraces of three domains, viz. glacial, fluvio-glacial 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 975m above m.s.l, and fluvial terraces at an average elevation between 650 to 900 m above m.s.l, The area of Upper Ganga basin consists of Alaknanda,Bhagirathi,Bhilangna, Nandakini, Mandakini, Pindar, Dhauli- Ganga Bal- Ganga , Madhmeshwar Ganga and Berhi Ganga. Amidst these Alaknnda is trunk stream and other are tributaries. The Alaknanda is chracterised by six fluvial terraces followed by Bhagirathi with five terraces , Bhilangna Nandakini four terraces Mandakini /Pindar/Dhauli-Ganga /Balganga three terraces , Madhmshwar Ganga two terraces and Bberhi Ganga one terraces. 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 faults /thrust 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 bears the impact of tectonic activity. The imprints of neotectonisam associated in the area indicate that these thrust /faults are active and have posed tectano-ecological problems, bears signatures of sinking of the area, mass wasting activities and neosiemic hazards. The study revealed that there is sharp curvilinear break in morphogenetic expression of the area In North of Wazri in Jamuna valley, North of Uttarkashi in Bhagirathi valley, around Tugnath and Chamoli and South of Joshimuth in Alaknanda valley, which appears to be due to horizontal movement of a sub - tectonic plates towards south, which is causative factor in dislocation in tectonic ecology of the area, it is matter of serious concerned and needs further attention.