publications

2023

1. Historical Structure from Motion (HSfM): Automated processing of historical aerial photographs for long-term topographic change analysis

   Friedrich Knuth, David Shean, Shashank Bhushan, Eli Schwat, Oleg Alexandrov, and 4 more authors

   Remote Sensing of Environment, Feb 2023

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2. icepyx: querying, obtaining, analyzing, and manipulating ICESat-2 datasets

   Jessica Scheick, Wei Ji Leong, Kelsey Bisson, Anthony Arendt, Shashank Bhushan, and 12 more authors

   Journal of Open Source Software, Apr 2023

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3. GLAcier Feature Tracking testkit (GLAFT): a statistically and physically based framework for evaluating glacier velocity products derived from optical satellite image feature tracking

   Whyjay Zheng, Shashank Bhushan, Maximillian Van Wyk De Vries, William Kochtitzky, David Shean, and 4 more authors

   The Cryosphere, Sep 2023

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   Abstract. Glacier velocity measurements are essential to understand ice flow mechanics, monitor natural hazards, and make accurate projections of future sea-level rise. Despite these important applications, the method most commonly used to derive glacier velocity maps, feature tracking, relies on empirical parameter choices that rarely account for glacier physics or uncertainty. Here we test two statistics- and physics-based metrics to evaluate velocity maps derived from optical satellite images of Kaskawulsh Glacier, Yukon, Canada, using a range of existing feature-tracking workflows. Based on inter-comparisons with ground truth data, velocity maps with metrics falling within our recommended ranges contain fewer erroneous measurements and more spatially correlated noise than velocity maps with metrics that deviate from those ranges. Thus, these metric ranges are suitable for refining feature-tracking workflows and evaluating the resulting velocity products. We have released an open-source software package for computing and visualizing these metrics, the GLAcier Feature Tracking testkit (GLAFT).

2022

1. Pre-collapse motion of the February 2021 Chamoli rock–ice avalanche, Indian Himalaya

   Maximillian Vries, Shashank Bhushan, Mylène Jacquemart, César Deschamps-Berger, Etienne Berthier, and 4 more authors

   Natural Hazards and Earth System Sciences, Oct 2022

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   Abstract. Landslides are a major geohazard that cause thousands of fatalities every year. Despite their importance, identifying unstable slopes and forecasting collapses remains a major challenge. In this study, we use the 7 February 2021 Chamoli rock–ice avalanche as a data-rich example to investigate the potential of remotely sensed datasets for the assessment of slope stability. We investigate imagery over the 3 decades preceding collapse and assess the precursory signs exhibited by this slope prior to the catastrophic collapse. We evaluate monthly slope motion from 2015 to 2021 through feature tracking of high-resolution optical satellite imagery. We then combine these data with a time series of pre- and post-event digital elevation models (DEMs), which we use to evaluate elevation change over the same area. Both datasets show that the 26.9×106 m3 collapse block moved over 10 m horizontally and vertically in the 5 years preceding collapse, with particularly rapid motion occurring in the summers of 2017 and 2018. We propose that the collapse results from a combination of snow loading in a deep headwall crack and permafrost degradation in the heavily jointed bedrock. Despite observing a clear precursory signal, we find that the timing of the Chamoli rock–ice avalanche could likely not have been forecast from satellite data alone. Our results highlight the potential of remotely sensed imagery for assessing landslide hazard in remote areas, but that challenges remain for operational hazard monitoring.

2021

1. Automated digital elevation model (DEM) generation from very-high-resolution Planet SkySat triplet stereo and video imagery

   Shashank Bhushan, David Shean, Oleg Alexandrov, and Scott Henderson

   ISPRS Journal of Photogrammetry and Remote Sensing, Mar 2021

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2. A massive rock and ice avalanche caused the 2021 disaster at Chamoli, Indian Himalaya

   Dan H. Shugar, Mylène Jacquemart, David Shean, Shashank Bhushan, Kavita Upadhyay, and 48 more authors

   Science, Jul 2021

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2020

1. A Systematic, Regional Assessment of High Mountain Asia Glacier Mass Balance

   David E. Shean, Shashank Bhushan, Paul Montesano, David R. Rounce, Anthony Arendt, and 1 more author

   Frontiers in Earth Science, Jan 2020

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2018

1. Assessing controls on mass budget and surface velocity variations of glaciers in Western Himalaya

   Shashank Bhushan, Tajdarul H. Syed, Anthony A. Arendt, Anil V. Kulkarni, and Debanjan Sinha

   Scientific Reports, Jun 2018

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   Abstract This study analyses spatially resolved estimates of mass budget and surface velocity of glaciers in the Zanskar Basin of Western Himalaya in the context of varying debris cover, glacier hypsometry and orientation. The regional glacier mass budget for the period of 1999–2014 is −0.38 ± 0.09 m w.e./a. Individual mass budgets of 10 major glaciers in the study area varied between −0.13 ± 0.07 and −0.66 ± 0.09 m w.e./a. Elevation changes on debris-covered ice are considerably less negative than over clean ice. At the same time, glaciers having \textgreater20% of their area covered by debris have more negative glacier-wide mass budgets than those with \textless20% debris cover. This paradox is likely explained by the comparatively larger ablation area of extensively debris-covered glaciers compared to clean-ice glaciers, as indicated by hypsometric analysis. Additionally, surface velocities computed for the 2013–14 period reveal near stagnant debris-covered snouts but dynamically active main trunks, with maximum recorded velocity of individual glaciers ranging between ~50 ± 5.58 and ~90 ± 5.58 m/a. The stagnant debris-covered extent, which varies from glacier-to-glacier, are also characterized by ice cliffs and melt ponds that appreciably increase the overall surface melting of debris-covered areas.

2017

1. Quantifying Changes in the Gangotri Glacier of Central Himalaya: Evidence for Increasing Mass Loss and Decreasing Velocity

   Shashank Bhushan, Tajdarul H. Syed, Anil V. Kulkarni, Prateek Gantayat, and Vibhor Agarwal

   IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, Dec 2017

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