Long-term near-bed observations of velocity and hydrographic properties inthe northwest Barents Sea with implications for sediment transport

Combined results from time-series observations of currents and water proper ties from two moorings and a benthic tripod measuring near-bed velocity pro files are used to evaluate the potential for sediment transport in the Stor fjord, east of Hopen Island, and in Olgastretet in the Barents Sea near the southeast Svalbard Archipelago. Current observations include a 15-month ti me series from each mooring with the lowermost current meter on each moorin g positioned at 6 mab and a 5-month time series from the tripod with four c urrent meters located within 1.2 mab. Threshold of grain motion was estimat ed from seabed sediment characteristics sampled at each site, bed roughness length was calculated from the benthic tripod velocity profiles. Results f rom the Storfjord and east of Hopen Island suggest that near-bed currents a nd bottom stresses cannot resuspend sediment in the summer months. Currents exceed the threshold of grain motion during the fall and winter months in response to strong flows forced by surface cooling and winds. Threshold of grain motion occurs for approximately 10 days per year in both the Storfjor d and east of Hopen Island. In Olgastretet, measured bottom currents had di stinct reversals from north to south over periods of 3-8 days throughout th e record. The highest currents (and largest bottom stresses) were directed southward and were high enough to resuspend bottom sediment about 19 days d uring the deployment period. Near-bottom flows are dominantly southward at all stations during times that sediment threshold velocities are exceeded, thus strong flows exiting the fjords in southern Svalbard during winter may also transport significant quantities of sediment into the deep northern N orwegian Sea. (C) 2001 Published by Elsevier Science Ltd.