Colloquium: Anastasia Piliouras

The Arctic is expected to have a pronounced response to climate change, including increased

fluxes of water, sediment, and nutrients to the coast, permafrost thaw, and decreasing sea ice

cover. However, Arctic coasts are understudied due to the difficulties of field-based research. In

this talk, I present results from a remote sensing analysis of six Arctic deltas and a reduced

complexity numerical modeling study, aimed at understanding Arctic delta morphologic

variability, the influence of morphology on the spatial and temporal distribution of land-ocean

fluxes, and the impact of permafrost and sea ice on delta morphology and morphodynamics. I

found an inverse relationship between the evenness of fluxes across the delta front and the lateral

expansiveness of the delta, such that smaller deltas distribute their fluxes evenly while larger

deltas favor fewer flow paths. This indicates that these six deltas may deliver most material to

the coast at discrete locations across a small area. The Mackenzie and Colville deltas have the

highest amount of lake coverage on the delta plain and the most lakes that are structurally

connected to the channel network, thus providing a means for transient storage of material as it

moves to the coast and potentially altering biogeochemical fluxes. Modeling results indicate that

both permafrost and landfast ice tend to make more persistent, stable channels, which changes

the storage and delivery of sediment through the deltas. Ice cover, especially, enhances offshore

deposition and overbank sedimentation, and thick ice cover can obstruct transport pathways until

the ice melts, thus creating temporal and spatial variability in transport pathways through the

deltas. Future work involves investigating these delta dynamics and changes to transport

pathways in response to a changing climate with thawing permafrost and diminishing sea ice

cover over time.