Browsing by Author "Purushottam Kumar Garg"

Now showing 1 - 3 of 3

Dulung Proglacial Lake, Suru Sub-Basin, Western Himalaya: Evolution, Controls and Impacts on Glacier Stability
(Frontiers Media S.A., 2022) Siddhi Garg; Purushottam Kumar Garg; Bisma Yousuf; Aparna Shukla; Uma Kant Shukla
Proglacial lakes are continually developing and expanding across the Himalayan glaciered terrain in response to climate change. These lakes are known to destabilize the glaciers by enhancing their frontal ablation, causing higher than average glacier area and mass losses. Thus, to comprehend the dynamics of proglacial lakes and their influence on the overall glacier health, we study the lake-terminating Dulung Glacier located in the Suru sub-basin, Ladakh, western Himalaya and compare it with the adjacent land-terminating Chilung Glacier. The pronounced melting of the Dulung Glacier, supported by glacier topography (surface gradient between accumulation and ablation zone) and valley morphology (wider near the snout and narrower downwards), seems to be the prime reason for the formation, accommodation and sustenance of the proglacial lake. The expansion in proglacial lake (.008 km2a−1) during 1977–2018 is accompanied by an enhanced degeneration of the Dulung Glacier (mass balance: −.47 ±.06 m w.e.a−1, shrinkage rate:.3 ±.001% a−1; retreat rate: 32 ±.7 ma−1, surface ice velocity reduction: 16%), which has accelerated post-1993. In comparison, land-terminating Chilung Glacier shows lower degeneration rates (mass balance: −.28 ±.02 m w.e.a−1; shrinkage rate:.2 ±.001% a−1; retreat rate: 17 ± 0.7 ma−1, surface ice velocity reduction: 8%) during 1971–2018. This suggests a substantial impact of the proglacial lake in enhancing the Dulung Glacier’s sensitivity towards climate change compared to the Chilung Glacier. If the current rate of lake expansion continues, it would further enhance the Dulung Glaciers’ degeneration rates, thus impacting its stability. Copyright © 2022 Garg, Garg, Yousuf, Shukla and Shukla.
Revisiting the 24 year (1994-2018) record of glacier mass budget in the Suru sub-basin, western Himalaya: Overall response and controlling factors
(Elsevier B.V., 2021) Siddhi Garg; Aparna Shukla; Purushottam Kumar Garg; Bisma Yousuf; Uma Kant Shukla; Sonam Lotus
Glacier mass balance time-series measurements have immense importance in comprehending the overall regional hydrology and meteorology of the mountain systems. Such assessments are critical in the Indus River basin (compared to the Ganga and Brahmaputra), which besides having a significant contribution from the glaciers, also exhibits considerable heterogeneity in glacier response. Thus, to quantify this variability in glacier behavior and thereby develop a comprehensive understanding of the past as well as the future evolution of the glaciers, we reconstruct the annual surface mass balance records of 75 glaciers (size >1 km2) in the Suru sub-basin, western Himalaya for the period 1994-2018. We apply a remote sensing-based equilibrium line altitude-mass balance approach, supported by geodetic mass balance estimates (for 18 major glaciers) and limited field measurements. Our findings suggest a persistent negative mass balance of the glaciers (average: -0.69 ± 0.28 m w.e.a-1, cumulative: -16.56 m w.e), varying from -0.46 ± 0.27 (1997) to -0.79 ± 0.28 (2018) m w.e.a-1 during the study period. This overall mass loss coincides with an increased temperature (Tavg increased 0.5 °C; Tmin increased 0.27 °C; Tmax increased 0.06 °C) and reduced precipitation (by 4%) in the valley during 1994-2018, which shows the sensitivity of these glaciers to climate change. Within the Suru sub-basin, smaller, cleaner and high-altitude mountain glaciers of the Ladakh range have experienced greater mass loss (cumulative: -20.88 m w.e) compared to the Greater Himalayan range (cumulative: -13.44 m w.e). We observe latitudinal variability in mass loss in the Western Himalaya, with the highest mass loss rates in the Greater Himalayan Range (>-0.9 m w.e.a-1) and lowest in the Karakoram Range (<-0.1 m w.e.a-1), suggesting a transitional response of the Suru sub-basin glaciers (-0.69 m w.e.a-1). The overall regional picture suggests synchronicity in the mass loss pattern of western Himalayan glaciers, predominantly controlled by the climatic conditions. Meanwhile, the variability in their mass loss rates is attributed to the unique glacier characteristics. © 2021
Surface evolution and dynamics of the Kangriz glacier, western Himalaya in past 50 years
(Elsevier B.V., 2022) Siddhi Garg; Aparna Shukla; Purushottam Kumar Garg; Bisma Yousuf; Uma Kant Shukla
Glacier specific studies, in a relatively unexplored terrain of Ladakh, hold immense importance tocomprehend not only the glacier response but also its synchronicity with the general regional trend. Accordingly, in this study, the Kangriz glacier in the Suru sub-basin, western Himalaya, has been taken up for multiparametric (area, terminal retreat, debriscover, snow line altitude, surface dynamics) assessment for the period 1971–2018. Results reveal an overall shrinkage of 3.3 ± 1.6%, with an expansion in the supraglacial debris cover by 45% (1971–2018). Concomitantly, the glacier surface velocity has reduced by 10.85 ± 5.68 ma−1 (35%), from 31.2 ± 5.8 ma−1 (1993/94) to 20.3 ± 1.7 ma−1 (2017/18), with mass wastage of ‐0.52 ± 0.19 m w.e.a−1 during 2000–17. The notable glacier degeneration is synchronous with regional warming (Tmax increase by 7%, Tmin increase by 43%, Tavg increase by 64%) and a decrease in precipitation by 3% (significant at α <0.05). Besides, frontal dynamics have changed recently, with an enhanced intensity of terminal retreat (2016–2018: 57 ± 13(Stdev) ma−1). The overall glacier status suggests a degenerative pattern of the glacier, which is in sync with the other western Himalayan glaciers. In view of the recently amplified ice-calving events and rapid mass loss observed in the snout region, the frontal glacier morphology may change drastically in the coming years. © 2022 Elsevier B.V.