The Development of Supraglacial Stream Canyons

• Main Author: St Germain, Sarah
• Other Authors: Moorman, Brian, Marshall, Shawn, Martin, Yvonne, Shugar, Daniel, Shea, Joseph
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Arts 2021
• Subjects: Glaciology; Supraglacial stream; Canyon; Physical Geography; Arctic; Bylot Island; Fountain Glacier; Greenland; Yukon; glacier; Alaska
• Online Access: http://hdl.handle.net/1880/113173; https://doi.org/10.11575/PRISM/38690

Supraglacial streams can dramatically into the glacier surface. On Fountain Glacier, Bylot Island, two large supraglacial streams have formed unique canyons. Supraglacial stream canyons have only been mentioned in the literature on a few occasions and process-level understanding is lacking. The aim of this research is to determine the processes impacting formation, time-scale of development, and distribution of supraglacial stream canyons. This was accomplished through three complementary studies: 1) an examination of short-term development of supraglacial streams, particularly in reference to surface, incised, and canyon stream formation; 2) an investigation of medium-term canyon meandering and erosion development and; 3) a determination of factors controlling worldwide canyon distribution, and a prediction of future distribution. These projects utilize high-resolution imagery collected on Fountain Glacier over time, and optical satellite imagery to map worldwide distribution of supraglacial stream canyons. This study has led to three major findings. 1) Canyons have a high likelihood of forming when the stream power is greater than 140 W/m. Canyon formation is limited in regions where stream power is low, where crevasses exist, and in areas where snow plugs are present within the channel. 2) Streambed erosion and widening at the bottom of the canyon creates greater area for solar radiation to differentially ablate the canyon walls. In 58 years, the studied canyon length, depth, and volume increased by 1607 m, 20 m, and 1.1x106 m3 due to a combination of fluvial erosion and solar radiation. It was found that glacier volume loss in the terminus region was comprised of 68.1% surface ablation, 25.8% glacier retreat /calving loss, and 6.1% canyon erosion. 3) Supraglacial stream canyons form in cold, dry regions, with a smooth glacier surface, free from crevasses in the Canadian Arctic, Northern Greenland, Alaska/Yukon, and Central / Northern Asia. This research has advanced our body of knowledge by determining how ...