Inventorying retrogressive thaw slump geomorphology using remotely piloted aircraft systems and evaluating associated downstream impacts
Abstract
Ice-rich permafrost landscapes are sensitive to ongoing changes in climate. Permafrost retrogressive thaw slumps (RTSs) represent one of the more abrupt and prolonged disturbances, which occur along Arctic river and lake shorelines. These features impact local travel and infrastructure, and there are concerns regarding associated impacts on biogeochemical cycling. Here we couple remotely piloted aircraft systems (RPAS) surveys with sediment and water analyses to monitor RTS geomorphology during 2016-19 and the biogeochemical influence of the largest active RTS along the Old Crow River in Old Crow Flats, Yukon, Canada. RPAS surveys revealed that 29,174 m3 of sediment was exported during the initial evacuation in June 2016 and an additional 18,845 m3 continued to be exported until June 2019. More sediment export occurred during the warmer and drier summer 2017 compared to summer 2018. However, several rain events during August 2017 were of higher intensity than in 2018. RPAS-derived multispectral and thermal data layers were used to distinguish geomorphic zones that have variable influence on sediment transport, establishment of vegetation, and biogeochemical properties within the RTS. Sediment total carbon and nitrogen (%) varied among classified zones. Total carbon and nitrogen exported to the Old Crow River was estimated using mean sediment values (1.5% and 0.12%, respectively). Chemical analysis of water sampled from up and downstream of the RTS revealed that aquatic mobilization of nutrients is highly episodic and dependent on high-river discharge events or stream runoff from the RTS. Approaches utilized here maximize the utility of multispectral and thermal datasets for identifying RTS geomorphological properties. Integrated in-situ biogeochemical measurements refine our knowledge of the associated impacts on downstream environments. Ongoing analysis is incorporating airborne datasets (e.g., AVIRIS-NG) and results from a water sampling network to scale approaches to the broader OCF landscape.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMB080.0024T
- Keywords:
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- 0414 Biogeochemical cycles;
- processes;
- and modeling;
- BIOGEOSCIENCES;
- 0428 Carbon cycling;
- BIOGEOSCIENCES;
- 0439 Ecosystems;
- structure and dynamics;
- BIOGEOSCIENCES;
- 0475 Permafrost;
- cryosphere;
- and high-latitude processes;
- BIOGEOSCIENCES