2021 CSDMS meeting-138


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Climate and process signatures on lake and wetland patterns in arctic river deltas

Lawrence Vulis, University of California, Irvine Irvine California, United States. lvulis@uci.edu
Alejandro Tejedor, Sorbonne University Abu Dhabi Abu Dhabi , United Arab Emirates.
Ilya Zaliapin, University of Nevada Reno Reno Nevada, United States.
Joel C. Rowland, Los Alamos National Laboratory Los Alamos New Mexico, United States.
Efi Foufoula-Georgiou, University of California Irvine Irvine California, United States.

River deltas ringing the Arctic Ocean coastline are unique landforms shaped by both highly seasonal cold region hydrology and permafrost features such as thermokarst lakes. These lakes trap, store, and modulate the timing and magnitudes of riverine freshwater, sediment, and nutrients. Future climate warming is expected to thaw permafrost, modifying lake coverage and therefore riverine flux delivery to the Arctic Ocean. How and where thermokarst lake coverage on deltas will change remains highly uncertain, in part due to the difficulty in separating perennially inundated thermokarst lakes which undergo thermal expansion in response to warming, from ephemeral wetlands resulting from interannual and seasonal hydrologic variability. We present a methodology that allows us to classify waterbodies as perennial lakes or ephemeral wetlands, by examining their presence in a 20 year record of Landsat imagery. By analyzing 12 deltas laying on a gradient of temperature and ice content, we find that perennial lakes and ephemeral wetlands have universal but distinct size distributions which result from different mechanisms forming the two waterbodies. We also find that colder deltas have larger lakes on average, mechanistically attributed to thicker and colder permafrost which supports larger lakes by preventing sub-lake unfrozen zones (i.e. taliks) from connecting to the sub-permafrost groundwater table. Lastly, we explore how differences in the spatial patterns of lakes across the deltas may relate to climate variability. These findings provide the basis for quantitative predictions for the trajectory of lake and wetland coverage on arctic deltas under projected warming.