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dc.contributor.authorWestoby, Matthew
dc.contributor.authorDunning, SA
dc.contributor.authorCarrivick, JL
dc.contributor.authorCoulthard, TJ
dc.contributor.authorSain, K
dc.contributor.authorKumar, A
dc.contributor.authorBerthier, E
dc.contributor.authorHaritashya, UK
dc.contributor.authorShean, DE
dc.contributor.authorAzam, MF
dc.contributor.authorUpadhyay, K
dc.contributor.authorKoppes, M
dc.contributor.authorMcCourt, HR
dc.contributor.authorShugar, DH

High-magnitude mass flows can have a pervasive geomorphological legacy, yet the short-term response of valley floors to such intense disturbances is poorly known and poses significant observational challenges in unstable landscapes. We combined satellite remote sensing, numerical modeling, and field observations to reconstruct the short-term geomorphological response of river channels directly affected by the 7 February 2021 ice-rock avalanche−debris flow in Chamoli district, Uttarakhand, India. The flow deposited 10.4 ± 1.6 Mm3 of sediment within the first 30 km and in places reset the channel floor to a zero-state condition, requiring complete fluvial re-establishment. In the 12 months post-event, 7.0 ± 1.5 Mm3 (67.2%) of the deposit volume was removed along a 30-km-long domain and the median erosion rate was 2.3 ± 1.1 m a−1. Most sediment was removed by pre-monsoon and monsoon river flows, which conveyed bedload waves traveling at 0.1−0.3 km day−1 and sustained order-of-magnitude increases in suspended sediment concentrations as far as 85 km from the event source. Our findings characterize a high-mountain fluvial cascade with a short relaxation time and high resilience to a high-magnitude geomorphological perturbation. This system response has wider implications, notably for water quality and downstream hydropower projects, which may be disrupted by elevated bedload and suspended sediment transport.

dc.publisherGeological Society of America
dc.subject7 Affordable and Clean Energy
dc.titleRapid fluvial remobilization of sediments deposited by the 2021 Chamoli disaster, Indian Himalaya
plymouth.publication-statusPublished online
plymouth.organisational-group|Plymouth|Faculty of Science and Engineering
plymouth.organisational-group|Plymouth|Faculty of Science and Engineering|School of Geography, Earth and Environmental Sciences
plymouth.organisational-group|Plymouth|Users by role
plymouth.organisational-group|Plymouth|Users by role|Academics

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