Sediment dynamics on Arctic shelves can impact coastal geomorphology, habitat suitability, and biogeochemical cycling, and are expected to be sensitive to changes in sea ice extent. Variability in coastal erosion, for example, has been related to variations in waves due to changes in sea ice extent, as well as water temperature. Yet, it remains unclear how changes in sea ice extent will impact hydrodynamic and sediment transport conditions on the continental shelf. To analyze this, we are using a coupled hydrodynamic - sediment transport numerical model, the Regional Ocean Modeling System (ROMS) - Community Sediment Transport Modeling System (CSTMS). The model is implemented for the Alaskan Beaufort Sea shelf and currently accounts for winds, sea ice, offshore currents, rivers, waves, and multiple sediment classes. Ongoing work includes finalizing model inputs. The model is being run for the 2019 open water season when sea ice retreats 100 - 300 km offshore. Analysis will focus on spatial and temporal variations in current velocities, waves, bed shear stresses, and sediment fluxes. Preliminary results show that the time-averaged depth-averaged currents, and likely sediment fluxes, are directed eastward along the shelf. Additionally, the largest bed shear stresses occur near the coast and on the shelf-slope break. Future work includes additional analyses, as well as sensitivity tests to better understand how a lengthening open water season and changing weather conditions may influence shelf sediment dynamics.
Graduate student Atmospheric and Oceanic Sciences, CU Boulder