A Remote sensing approach for monitoring debris-covered glaciers in the high altitude Karakoram Himalayas

Debris-covered glaciers, unlike other types of glaciers, are difficult to map using visible and infrared imagery. Moreover, high altitude glaciers are difficult to map using fieldwork data due to the inaccessibility. In this study, supraglacial debris cover is mapped using Landsat TM and ETM+ images acquired from 1990 to 2010 and a digital elevation model (DEM) which is derived from Shuttle Radar Topographic Mission (SRTM) acquired in 2002. Image processing steps and vectorisation were done using Erdas 2011 and ArcGIS software packages. Different methods include manual, semi-automatic, modified semi-automatic, and automatic method using thermal wavebands. Application of band ratio images is also used. Changes in debris extent and debris-covered glaciers in the study site during this period were also calculated. These methods for mapping supraglacial debris cover were found to give comparable results. However some discrepancies may arise due to the poor spatial resolution of images, seasonal variations and lack of fieldwork. It is expected that a high spatial and spectral resolution imagery combined with field work data and surface ablation characteristics would produce better map of debris-covered glaciers.