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Six small coastal moorings were deployed in Harrison Bay for approximately 30 days between early August and early September. Two moorings were outfitted with Nortek Aquadopps and optical backscatter sensors and the remainder were outfitted with RBR sensors which recorded some combination of salinity, temperature, pressure, and turbidity. All sensors were mounted within approximately 0.5 meters (m) of the bed to capture boundary-layer dynamics. Turbidity values were converted to total suspended solids concentrations. Wave parameters (significant wave height, peak wave period, and wave direction) were post-processed from Aquadopp data. Shear velocities (used in sediment-transport research) were calculated from current and wave data at the sites where Aquadopps were mounted. Data have been used in support of a publication, "Summertime sediment convergence on the Alaskan Beaufort Shelf and implications for ice rafting." 

Four small coastal moorings were deployed in water depths of ~5-6 meters (m) on the Colville Delta front and one site farther west for a period of approximately one week in Jul/Aug 2021. Moorings were outfitted with sensors to collect a variety of data including water levels (at all sites), turbidity/total suspended solids, water velocity, salinity, temperature, and light intensity. Light intensity measurements were also collected from a vessel-mounted sensor (included in the MM3 data package) to allow for calculation of light attenuation at the mooring. These data are described more fully in a companion publication (Eidam, "Summertime water and particle properties on an ice-influenced Arctic shelf", in prep as of March 2025). 

This dataset includes water-column data collected from the Beaufort Shelf during the open-water seasons in 2020, 2021, and 2022. The 2020 data include water-column profiles (salinity, temperature, depth, turbidity, particle size distributions, particle volume concentrations, and uncorrected clorophyll-a) collected with an RBR CTD/Tu (conductivity, temperature, depth, turbidity) sensor and LISST sensor from R/V Sikuliaq and its workboat. Most sites were in the Harrison Bay region (north of the Colville Delta and Simpson Lagoon) and a few were located farther east. The 2021 and 2022 data include the same CTD/Tu and LISST data that were collected in 2020, but are focused in Harrison Bay and also include profiles of light intensity (photosynthetically active radiation) as well as ADCP (acoustic doppler current profile) profiles from a pole-mounted Nortek Signature 500 kilohertz (kHz) sensor. In 2021, additional data include filtration data (total suspended solids, suspended sediment concentrations, and organic fractions) from water samples and hi-resolution echosounder data from the Nortek ADCP. These data are being incorporated into publications about summertime water-column properties and sediment transport dynamics within Harrison Bay (Eidam et al., pending). 

This dataset contains ascii text files of latitude, longitude, and water depth data which were collected using a pole-mounted multibeam echosounder system from the R/V Ukpik in July-August, 2021. Dr. Emily Eidam was the team lead and Dan Duncan was the multibeam operator. The data were collected along discrete tracklines across Harrison Bay. The general study was seaward of the Colville Delta between Cape Halkett to the west and Oliktok Point to the east, with a maximum seaward extent to water depths of approximately 30 meters (m) (about half to three-quarters of the way across the shelf from the shoreline). The dataset also contains a netcdf file of bathymetric change which was computed as the difference between the combined 2021 and 2022 data contained in this archive and a 1950s dataset which was recently corrected and is publicly available through Zimmerman et al., 2022 (doi.org/10.1016/j.csr.2022.104745). The multibeam data provide information about a rich diversity of seabed features including large and small ice-keel scours, sand waves, strudel scour pits, and unusual scoured substrates. A detailed description of these datasets is provided in an in-preparation manuscript (Eidam et al., Seafloor sediments and morphologic features of Harrison Bay in the Alaskan Beaufort Sea). The bathymetric change data illustrates erosion of the inner and inner-middle shelf over the past ~70 years, including erosion of up to ~3 m near Cape Halkett and on the Colville Delta front. These changes are addressed in detail in Heath, 2024 (Oregon State University Master of Science Thesis, "Sedimentation and Erosion on an Arctic Continental Shelf: Harrison Bay and Colville River Delta, Alaska"). 

Abstract Seasonal sea ice impacts Arctic delta morphology by limiting wave and river influences and altering river‐to‐ocean sediment pathways. However, the long‐term effects of sea ice on delta morphology remain poorly known. To address this gap, 1D morphologic and hydrodynamic simulations were set up in Delft3D to study the 1500‐year development of Arctic deltas during the most energetic Arctic seasons: spring break‐up/freshet, summer open‐water, and autumn freeze‐up. The model focused on the deltaic clinoform (i.e., the vertical cross‐sectional view of a delta) and used a floating barge structure to mimic the effects of sea ice on nearshore waters. From the simulations we find that ice‐affected deltas form a compound clinoform morphology, that is, a coupled subaerial and subaqueous delta separated by a subaqueous platform that resembles the shallow platform observed offshore of Arctic deltas. Nearshore sea ice affects river dynamics and promotes sediment bypassing during sea ice break‐up, forming an offshore depocenter and building a subaqueous platform. A second depocenter forms closer to shore during the open‐water season at the subaerial foreset that aids in outbuilding the subaerial delta and assists in developing the compound clinoform morphology. Simulations of increased wave activity and reduced sea‐ice, likely futures under a warming Arctic climate, show that deltas may lose their shallow platform on centennial timescales by (a) sediment infill and/or (b) wave erosion. This study highlights the importance of sea ice on Arctic delta morphology and the potential morphologic transitions these high‐latitude deltas may experience as the Arctic continues to warm. 

Sediments covering Arctic continental shelves are uniquely impacted by ice processes. Delivery of sediments is generally limited to the summer, when rivers are ice free, permafrost bluffs are thawing, and sea ice is undergoing its seasonal retreat. Once delivered to the coastal zone, sediments follow complex pathways to their final depocenters—for example, fluvial sediments may experience enhanced seaward advection in the spring due to routing under nearshore sea ice; during the open-water season, boundary-layer transport may be altered by strong stratification in the ocean due to ice melt; during the fall storm season, sediments may be entrained into sea ice through the production of anchor ice and frazil; and in the winter, large ice keels more than 20 m tall plow the seafloor (sometimes to seabed depths of 1–2 m), creating a type of physical mixing that dwarfs the decimeter-scale mixing from bioturbation observed in lower-latitude shelf systems. This review summarizes the work done on subtidal sediment dynamics over the last 50 years in Arctic shelf systems backed by soft-sediment coastlines and suggests directions for future sediment studies in a changing Arctic. Reduced sea ice, increased wave energy, and increased sediment supply from bluffs (and possibly rivers) will likely alter marine sediment dynamics in the Arctic now and into the future. 

This file contains grain-size data from seabed shipek grab samples collected from R/V Ukpik in summer 2021 as part of NSF project 1913195 (Arctic Shelf sediment fate – an observational and modeling study of sediment pathways and morphodynamic feedbacks in a changing polar environment). Samples were collected from across Harrison Bay on the Alaskan Beaufort Shelf, north of the Colville River and between Oliktok Point and Cape Halkett. Samples were bagged in the field and returned to the University of North Carolina at Chapel Hill where grain-size analyses were performed using an Escitec Bettersizer S3Plus laser diffraction sensor. Samples were sonicated for two minutes prior to analyses. Samples ranged from well sorted sands (typically medium sand or fine) to poorly sorted bimodal sands and muds to unimodal muds. In the field, samples exhibited diverse textures including mud clasts and very stiff muds. 

In this study, we developed a 1D Delft3D-FLOW model to simulate the temporal development of the Colville River Delta, Alaska during the most active Arctic seasons: break-up/freshet (spring), open-water (summer), and freeze-up (fall). Simulations focused on the deltaic clinoform (i.e., the cross-sectional view of a delta) and used a floating barge structure to mimic the effects of sea ice on surface waters. Delft3D simulations were coupled with modules written in MATLAB and outputs were process in MATLAB. Arctic delta morphology is impacted by seasonal sea ice coverage which significantly limits wave and river influences and alters river-to-ocean sediment dispersal. However, our knowledge of the morphologic influences of ice on delta morphology is relatively limited. To assess the role of sea ice, our study used a model to explore long-term Arctic delta development under seasonal ice, river, and wave conditions. Delta developmental simulations (spanning 1500 years) included ice-free and ice-affected cases. These cases consisted of simulations with and without waves to separately examine and compare sea ice, river, and wave impacts on Arctic delta evolution. Long-term delta developmental simulations showed ice-affected deltas form a compound clinoform morphology – a coupled subaerial and subaqueous delta separated by a subaqueous platform that resembles the shallow 2 meter platform observed offshore of Arctic deltas. In the model, the presence of nearshore sea ice and river forcing promoted sediment bypassing during break-up, forming a depocenter up to 6 km away from the river mouth and were the key drivers behind platform formation. Furthermore, six varying sea-ice characteristics (extent and thickness) were evaluated to examine effects on delta development for the first 500 years. We found that the compound clinoform morphology modulated by sea ice was heavily dependent on ice conditions, with closer and thicker sea ice produced a more elongated subaqueous platform. In addition to long-term delta developmental simulations, we examined two future scenarios (spanning 450 years) to assess future Arctic delta morphology with less seasonal sea ice coverage and larger waves as predicted by climate models. Modeled future simulations showed Arctic deltas may lose the shallow 2 meter platform feature on centennial timescales by (1) sediment infill or (2) wave erosion. This study highlights the importance of sea ice on Arctic delta morphology and the potential morphologic transitions these high-latitude deltas may experience as the Arctic continues to warm. The dataset includes an example model run file (Delft3D-FLOW and MATLAB) and output of results from the described simulations. Files include: 1) Example Delft3D-FLOW model setup file, MATLAB run script, and ice files for a 1500-year simulation. 2) Processed MATLAB structures and metadata for model results A) Long-term Delta Developmental Outputs (1500-year simulations) i) Ice-free ii) Ice-affected iii) Ice-free with waves iv) Ice-affected with waves B) Varying Sea Ice Characteristics Outputs (500-year simulations) i) Ice matrix (six simulations) C) Future Arctic Delta Scenarios Outputs (450-year simulations) i) Scenario A ii) Scenario B