|
Investigating Lake Area Dynamics as a Function of Permafrost Degradation Using Airborne Electromagnetic Surveys in Yukon Flats, AK
David
Rey, Hydrologic Science and Engineering Program, Colorado School of Mines, U.S. Geological Survey, drey@mymail.mines.edu
(Presenter)
High arctic warming rates are changing the routing and storage of water above and below the ground surface, potentially impacting surface-water dominated regions such as boreal lowlands, where evolving permafrost dynamics are affecting the regional hydrology and biogeochemical cycling of carbon. The Yukon Flats, Alaska, is an expansive boreal lowland primarily underlain by discontinuous permafrost, making the region particularly sensitive to a warming climate. Consequently, the shallow, continuous, fluvial gravel layer existing within the Yukon Flats may be transitioning from relatively impermeable to highly permeable if thawed. This makes the Yukon Flats and other boreal lowlands with high permeability material susceptible to increasing shallow subsurface connectivity between lakes and stream networks as permafrost degrades. Increased subsurface connectivity as a function of permafrost degradation could potentially alter lake dynamics within these regions, perturbing terrestrial surface conditions and changing energy and carbon partitioning in affected boreal lowlands. This study presents a synthesis of new data products and methods with previous work, identifying linkages between permafrost distribution, hydrologic connectivity (surface and subsurface), and decadal-scale trends in surface water dynamics. New Airborne Electromagnetic (AEM) data acquisitions coupled with expanded, co-located Landsat data provided an ice-rich analog to an existing Yukon Flats AEM survey, allowing for comparisons between lakes in more continuous and discontinuous permafrost settings not previously possible. Landsat derived lake surface area time-series behaviors were clustered to correlate individual lake surface area trends, measure lakes proximity to adjacent rivers and streams, and evaluate average lake-surface area extent. Landsat data was coupled with AEM data to identify permafrost distribution underlying the identified clusters, elucidating five physical processes governing observed lake surface-area heterogeneity. Processes driving lake surface area dynamics differed between regions of continuous and discontinuous permafrost, providing important context for projecting future spatial and temporal patterns of lake change in boreal lowlands. Associated Project(s): Poster Location ID: 105 Session Assigned: Permafrost and Hydrology
|