Impacts of Permafrost Degradation on a Stream in Taylor Valley, Antarctica
The McMurdo Dry Valleys (MDV) of Antarctica are an ice-free landscape that supports a complex, microbially dominated ecosystem despite a severely arid, cold environment (< 5 cm water equivalent/y, − 18 °C mean annual air temperature). Recent observations of permafrost degradation in the coastal z...
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ftportlandstate:oai:pdxscholar.library.pdx.edu:geology_fac-1111 2023-05-15T13:52:19+02:00 Impacts of Permafrost Degradation on a Stream in Taylor Valley, Antarctica Sudman, Zachary Gooseff, Michael N. Fountain, Andrew G. Levy, Joseph S. 2017-05-15T07:00:00Z https://pdxscholar.library.pdx.edu/geology_fac/111 unknown PDXScholar https://pdxscholar.library.pdx.edu/geology_fac/111 Geology Faculty Publications and Presentations Geology text 2017 ftportlandstate 2022-01-09T19:44:23Z The McMurdo Dry Valleys (MDV) of Antarctica are an ice-free landscape that supports a complex, microbially dominated ecosystem despite a severely arid, cold environment (< 5 cm water equivalent/y, − 18 °C mean annual air temperature). Recent observations of permafrost degradation in the coastal zones of the MDV suggest that this region is nearing a threshold of rapid landscape change. In 2012, substantial thermokarst development was observed along several kilometers of the west branch of Crescent Stream in Taylor Valley mostly in the form of bank failures, whereas the adjacent east branch was unaffected. The objective of this study was to quantify the changes to the stream banks of the west branch of Crescent Stream and to determine the impacts on the composition of the stream bed material. Three annually repeated terrestrial LiDAR scans were compared to determine the rates of ground surface change caused by thermokarst formation on the stream bank. The areal extent of the thermokarst was shown to be decreasing; however, the average vertical rate of retreat remained constant. Field measurements of bed materials indicated that the west branch and the reach downstream of the confluence (of east and west branches) consistently contained more fines than the unaffected east branch. This suggests that the finer bed material is a result of the thermokarst development on the west branch. These finer bed material compositions are likely to increase the mobility of the bed material, which will have implications for stream morphology, stream algal mat communities, and downstream aquatic ecosystems. Text Antarc* Antarctica Ice McMurdo Dry Valleys permafrost Thermokarst Portland State University: PDXScholar Crescent Stream ENVELOPE(163.183,163.183,-77.617,-77.617) McMurdo Dry Valleys Taylor Valley ENVELOPE(163.000,163.000,-77.617,-77.617) |
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Portland State University: PDXScholar |
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Geology |
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Geology Sudman, Zachary Gooseff, Michael N. Fountain, Andrew G. Levy, Joseph S. Impacts of Permafrost Degradation on a Stream in Taylor Valley, Antarctica |
topic_facet |
Geology |
description |
The McMurdo Dry Valleys (MDV) of Antarctica are an ice-free landscape that supports a complex, microbially dominated ecosystem despite a severely arid, cold environment (< 5 cm water equivalent/y, − 18 °C mean annual air temperature). Recent observations of permafrost degradation in the coastal zones of the MDV suggest that this region is nearing a threshold of rapid landscape change. In 2012, substantial thermokarst development was observed along several kilometers of the west branch of Crescent Stream in Taylor Valley mostly in the form of bank failures, whereas the adjacent east branch was unaffected. The objective of this study was to quantify the changes to the stream banks of the west branch of Crescent Stream and to determine the impacts on the composition of the stream bed material. Three annually repeated terrestrial LiDAR scans were compared to determine the rates of ground surface change caused by thermokarst formation on the stream bank. The areal extent of the thermokarst was shown to be decreasing; however, the average vertical rate of retreat remained constant. Field measurements of bed materials indicated that the west branch and the reach downstream of the confluence (of east and west branches) consistently contained more fines than the unaffected east branch. This suggests that the finer bed material is a result of the thermokarst development on the west branch. These finer bed material compositions are likely to increase the mobility of the bed material, which will have implications for stream morphology, stream algal mat communities, and downstream aquatic ecosystems. |
format |
Text |
author |
Sudman, Zachary Gooseff, Michael N. Fountain, Andrew G. Levy, Joseph S. |
author_facet |
Sudman, Zachary Gooseff, Michael N. Fountain, Andrew G. Levy, Joseph S. |
author_sort |
Sudman, Zachary |
title |
Impacts of Permafrost Degradation on a Stream in Taylor Valley, Antarctica |
title_short |
Impacts of Permafrost Degradation on a Stream in Taylor Valley, Antarctica |
title_full |
Impacts of Permafrost Degradation on a Stream in Taylor Valley, Antarctica |
title_fullStr |
Impacts of Permafrost Degradation on a Stream in Taylor Valley, Antarctica |
title_full_unstemmed |
Impacts of Permafrost Degradation on a Stream in Taylor Valley, Antarctica |
title_sort |
impacts of permafrost degradation on a stream in taylor valley, antarctica |
publisher |
PDXScholar |
publishDate |
2017 |
url |
https://pdxscholar.library.pdx.edu/geology_fac/111 |
long_lat |
ENVELOPE(163.183,163.183,-77.617,-77.617) ENVELOPE(163.000,163.000,-77.617,-77.617) |
geographic |
Crescent Stream McMurdo Dry Valleys Taylor Valley |
geographic_facet |
Crescent Stream McMurdo Dry Valleys Taylor Valley |
genre |
Antarc* Antarctica Ice McMurdo Dry Valleys permafrost Thermokarst |
genre_facet |
Antarc* Antarctica Ice McMurdo Dry Valleys permafrost Thermokarst |
op_source |
Geology Faculty Publications and Presentations |
op_relation |
https://pdxscholar.library.pdx.edu/geology_fac/111 |
_version_ |
1766256595583369216 |