Elevation dependent thickness and ice-volume estimation using satellite derived DEM for mountainous glaciers of Karakorum range

Abstract

Mountainous glaciers are best climate indicators and contributing to sea level fluctuation in response of any climatic change. The mean thickness and ice volume of these glaciers are the important parameter to justify glacier response to climate and, calculated using Glaptop approach and Area-Volume Scaling law respectively in some of the studies. However, thickness and ice-volume are significantly dependent on elevation and their elevation based distribution is important for the health of any individual glacier. Glaciers of Karakoram range in HKKH region which are famous for stability have significant variance in elevation where, Glaptop approach and Area-Volume Scaling law for calculation of thickness and ice volume over different elevations of an individual glaciers in range is not being properly exploited. This paper is presented with the study of elevation-based thickness and ice-volume through satellite-based DEM for two selected glaciers with GLIMS-ID of G074684E36059N & G074575E36099N of Gilgit river sub-basin. The objective of the study is to estimate thickness and ice-volume over different elevations through spaceborne elevation model and, appraise the stability of glaciers in Karakoram range. GDEM from ASTER and the glacier outline clipped from RGI are the basic input parameters. ArcGIS 10.3 exploited for the extraction of morphometrical parameters of an individual glacier. Mathematical expressions of Glaptop and Area-Volume Scaling law used with morphometrical parameters to provide distributed thickness and ice-volume mapping of individual glaciers over different elevations. The distributed values further analysed to examine the relationship of these parameters with morphometric attributes. Visualization of the derived maps for distributes thickness and ice-volume provided a diversified nature for the selected glaciers of the study area. The thickness of glacier (G074684E36059N) ranged from 0.24-87.31 m has higher magnitude in lower elevation near the glacier snot in contrast of the glacier (G074684E36059N) which has maximized value of thickness along mid elevation zone in the ranged of 03.19-42.08 m. The ice-volumetric range of glacier (G074684E36059N) recorded greater than glacier (G074684E36059N) in lower elevation zone which is eventually the effect of the area in said zone. In linear regression analysis, positive correlation of thickness and ice-volume with area logged for both glacier. The diverse distributed values of thickness and ice-volume concluded the variance in intensity of vulnerability of selected glaciers in the basin toward the climate change where, the positive correlation established the dependency on area under different elevation intervals. Furthermore, the statistical values extracted with correlation presented for proper protective management of the glacier component in Karakoram range and a supportive knowledge in the context of Karakoram anomalies.