Under‐Ice Hydrography of the La Grande River Plume in Relation to a Ten‐Fold Increase in Wintertime Discharge

• Published in: Journal of geophysical research. Oceans 2022-10, Vol.127 (10), p.n/a
• Main Authors: Peck, Christopher J., Kuzyk, Zou Zou A., Heath, Joel P., Lameboy, John, Ehn, Jens K.
• Format: Article
• Language: English
• Subjects: Aquatic plants; Coastal waters; Coasts; Downstream; eelgrass habitat; Environmental changes; Estuaries; Fresh water; Freshwater; Freshwater ice; Geophysics; Habitats; High flow; Hydroelectric power; Hydrography; Ice; Ice cover; Ice formation; Inland water environment; La Grande River plume extent; landfast ice; Marine environment; Migrations; River discharge; River flow; River mouth; River mouths; River plumes; River water; Rivers; Salinity; Salinity effects; Sea grasses; Stratified water; Surface boundary layer; Surface layers; Surveying; Turnover rate; under‐ice river plume; Water circulation; Water column; Water discharge; Waterfowl; Winter
• ISSN: 2169-9275; 2169-9291
• DOI: 10.1029/2021JC018341

A large under‐ice plume forms because of the regulated winter discharge from the La Grande River hydroelectric complex (NE James Bay, Canada), which is among the largest winter discharges in the circumpolar north. In 2016–2017, field campaigns were completed to characterize the under‐ice plume's structure, extent, and short‐term dynamics related to tides, weather, and discharge. Amid concerns of the freshwater's impact on eelgrass, the lateral spreading of the under‐ice plume into inshore areas was also assessed. When discharges averaged 4,800 m3 s−1 throughout the January–March periods, the freshwater influence of La Grande River extended more than 100 km north along the James Bay coast, with the brackish (salinity