Glacial-geomorphic study of the Thajwas glacier valley, Kashmir Himalayas, India

Abstract

Glacial-geomorphic studies provide vital information to make inferences about the effect of glacial advance and retreat on the geomorphology of an area. In the present study, glacial-geomorphic landforms of the Thajwas glacial valley in the upper reaches of the Indus, Kashmir Himalayas were mapped using geospatial technology validated with GPS-based field observations and ground photography. The glacial-geomorphic landforms were digitized using ASTER DEM (30 m resolution), Landsat ETM+ satellite imagery (30 m resolution) and Google Earth (1 m resolution) data. Results showed that Google Earth imagery, supported by field validation, is very useful for the interpretation of glacial-geomorphic landscapes and relief features at micro- and meso-scales. However, morphometric characteristics of landforms are best obtained using DEM overlaid onto the Landsat ETM+ satellite data. Glaciers in the valley are presently confined along the south and southwestern slopes. However, the significant role played by glaciers in shaping the geomorphic landforms and their subsequent preservation within the scenic landscape under the Late Quaternary climatic conditions are remarkably evident. The glacial-geomorphic landforms, especially terminal moraine, glacial trough and cirques observed in the valley aided the reconstruction of palaeo-glacial setting of the area. Morphology, shape and location of terminal and lateral moraine ridges were used to establish the palaeo-glacial extents, glacial volume and the number of glacial advances of the Thajwas glacier. The maximum elevation of the lateral moraines was used to define the former Equilibrium-Line Altitude (ELA). The greater rock excavation to form a large valley during the last glacial maximum might have induced isostatic rock uplift/exhumation in the glacier source area. It is observed that the concomitant retreat of the north-facing glacial cirques has played an important role in expanding the glacial valley and limiting the topographic relief.