Surface Drift and Dispersion in a Multiply Connected Fjord System

The deployment of 206 surface drifters over 3 years in a fjord system in northern British Columbia allows examination of drift and dispersion in complex coastal regions on time scales up to 10 days. The surface drift is found to be seasonally variable, with stronger dispersion and outflows in the spring and fall, and negligible outflow in the summer. Dispersion at time scales less than 10 hr is well described by fractional Brownian motion, where the drifter tracks exhibit fractal characteristics with a dimension of 1.34 over scales of 2 to 13 km. Drifters are found to reach less energetic nearshore regions within 12-15 hr, which slows along-channel dispersion. The comparison of the drifter statistics (from 2014-2016) with observations of the spatial distribution of oil sheen following an oil spill in 2006 shows that the drifter results provide a reasonable proxy for oil drift in this area. A statistical model for the extent of along-channel transport of spilled oil is proposed for use in planning emergency response activities in the area. Plain Language Summary This paper is an analysis of the movement of 206 surface drifting buoys (drifters), which were released in the Kitimat fjord system in northwestern British Columbia between 2014 and 2016. This fills a knowledge gap concerning drift of objects at the ocean surface in narrow fjord systems over times longer than 1 day. Drift is toward the ocean on average and stronger in the spring and fall than in the summer. Drifters move approximately twice as fast near midchannel than they do near the shorelines and are found to come in close proximity of the shoreline within 12-15 hr of being released. Consequently, this cross-channel movement slows drift along the channel. Comparison with observations of sheening from a previous oil spill in the study region suggests that the drifters are an adequate proxy for spilled oil. A statistical model for the maximum likely extents of oil spills in the fjord system after times up to 10 days is proposed.