Assessment of Rock Glacier Dynamics and Infiltration-Driven Thinning in the Accumulation Region through SAR Interferometry with VV-Polarized Sentinel-1A/1B SAR Data

Abstract

In this study, we estimated the spatial distribution of rock glacier velocities and elevation changes over the region of the Indian state of Himachal Pradesh. The rock glacier velocities are estimated by using the Differential Synthetic Aperture Radar Interferometric (DInSAR) technique. DInSAR is observed as accurate and optimum for rock glacier dynamic studies. From the 185 rock glaciers selected for this study, 127 of them are moving with a mean velocity of 35 cm/yr. (≈ 1 mm/day). However, none of these rock glaciers mean velocities exceed 100 cm/yr. The elevation change of rock glaciers is estimated using the DEM differencing technique. The DEM differencing with the SRTM C-band DEM and TanDEM-X DEM was employed to estimate the rock glaciers thickness change from 2000 to 2014. Among 185 glaciers, the mean thickness change is positive for 58 rock glaciers and negative for 127 rock glaciers. The elevation change of rock glaciers is ranging from − 19 m (thinning) to 10 m (mass gain) for 2000–2014 time period. The mean annual elevation change of these rock glaciers is observed as − 0.175 m. The study also compared the previous research work related to the ice glaciers velocity and thickness changes of this same region. Similar to the velocity, the elevation change of rock glaciers is smaller compared to the ice glaciers. In general, the thinning of the ice glaciers is associated with the ablation region, and mass gain with the accumulation region. Despite the significant evidence of thinning is observed mostly in the accumulation region for the rock glaciers. These elevation changes are correlated with the velocity measurements for the notable rock glaciers. Most of the rock glaciers observed high velocities in the accumulation region are also observed the thinning in the same region. The correlation of these two parameters might be associated with infiltration. However, the designated analysis of the rock glacier’s internal structure is expected to provide a correlation between the velocity and thickness change of the rock glaciers.