2025 CSDMS meeting-061
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Source Composition of Suspended Sediment Concentrations on the Alaskan Beaufort Sea Shelf
Brianna Undzis,
(she/her/hers),University of Colorado Boulder Boulder Colorado, United States. brianna.undzis@colorado.edu
Julia Moriarty, University of Colorado Boulder Boulder Colorado, United States. Julia.Moriarty@colorado.edu
Suspended sediment concentrations and fluxes on continental shelves impact light attenuation and primary productivity, as well as geomorphology and incorporation of particles into sea ice. As Arctic permafrost thaws, increasing riverine delivery and shoreline erosion, it is particularly important to understand how sediment sources influence suspended sediment concentrations and transport. To investigate these topics, this study analyzed results from a coupled hydrodynamic - sediment transport numerical model, namely the Regional Ocean Modeling System (ROMS) - Community Sediment Transport Modeling System (CSTMS). The model was implemented for the Alaskan Beaufort Sea Shelf for the 2020 open water (nearly ice-free) season, and accounted for processes such as riverine delivery, winds, larger-scale currents, and sediment erosion, transport and deposition. Building on previous work, we categorized riverine and seabed sediments into 26 distinct classes that allow us to distinguish among material originating from different rivers and sections of the seabed. Analysis focused on the spatial distribution of riverine and nearshore sediments over the course of an open water season, as well as the extent to which each sediment class contributed to high turbidity events. Preliminary results suggested that aggregated mud delivered by rivers during an open water season stayed within water depths of 0 – 10 m for at least a month and a half, while some unaggregated mud was transported to deeper regions during this time. Additionally, high turbidity events mainly occurred due to local resuspension, as opposed to riverine plumes, for both aggregated and unaggregated mud. Ongoing and future work include analysis of uncertainty due, for example, to sediment settling velocity and other properties. Overall, these findings suggest that high turbidity events are driven by sediment delivered to the continental shelf during previous open water seasons or winters, as opposed to new terrestrial/riverine inputs.
