GLACIER MASS BALANCE AND VELOCITY ANALYSIS USING D-INSAR AND OFFSET TRACKING TECHNIQUE: A CASE STUDY OF BATURA, PASSU, GHULKIN, AND GULMIT GLACIERS, HUNZA RIVER BASIN

Abstract

In the context of climate change, monitoring glaciers’ movement and mass balance is important for water resource management and glacier avalanche hazard to downstream population and infrastructure. Himalayas, Karakoram and Hindukush ranges in Pakistan are home to some of the largest valley glaciers in the world. Synthetic Aperture Radar (SAR) data has greatly contributed to the study of glaciers because of accurate estimation of small displacements on Earth surface and availability of data all year round. The aim of this study was to investigate the potential of Sentinel 1A satellite SAR data to estimate the mass balance and velocity of Batura, Passu, Ghulkin, and Gulmit glaciers in Hunza river basin Pakistan. Differential InSAR (D-InSAR) and small baseline (SBAS) techniques were used to determine mass balance using Sentinel 1A Interferometric Wide Swath (IW) data, while Offset tracking method was used to estimate the surface velocity of glaciers using Ground Range Detected (GRD) data from year 2017-2022. Subpar findings were yielded in the evaluation of glacier mass balance because of low coherence. The Offset tracking showed promising results for estimation of glacier velocity. The result showed that the glaciers exhibit a high rate of movement at higher altitudes, which subsequently diminishes towards the glacier's terminus, with peak velocity occurring in the central region of the glacier. Passu glacier showed highest velocity with average velocity exceeding 100 m/year. The research findings indicated that Sentinel 1A SLC (IW) is unsuitable for interferometric method to estimate the mass balance of glaciers in the study area because of low coherence. A very small temporal base line data should be used to overcome low coherence over the glaciers.