Paraglacial landscape evolution in a rapidly deglaciating environment : a case study of Taan Fjord, Southeast Alaska, USA ...

• Main Author: Williams, Haley
• Format: Text
• Language: English
• Published: University of British Columbia 2018
• Subjects: glacier; Alaska
• Online Access: https://dx.doi.org/10.14288/1.0370948; https://doi.library.ubc.ca/10.14288/1.0370948

The rapid thinning and retreat of Tyndall Glacier in Taan Fjord in Southeast Alaska has exposed 8 fluvial tributary watersheds to fast-acting paraglacial denudation processes. An average base-level fall of ~400 m has resulted in increased sediment yields and basin-averaged erosion rates in the watersheds over the first decades following the exposure of their outlets to the ocean. We used structure from motion photogrammetry to reconstruct the rate of surface thinning of Tyndall Glacier since 1957 and the rate of base-level fall for the tributaries. We modelled each fan-delta to obtain a minimum estimate of total sediment volume evacuated from each watershed and used geometric relations to determine sediment yields and erosion rates for each tributary through time. Between 1969 and 2014, the tributary basins contributed 165.7 ± 16.0 million m³ of total sediment to the fjord, or double the amount of sediment contributed by Tyndall Glacier. On average, the tributaries eroded their watersheds at a rate of 36.0 ± ...