Characteristics and Trends of River Discharge into Hudson, James, and Ungava Bays, 1964–2000

• Published in: Journal of climate Vol. 18; no. 14; pp. 2540 - 2557
• Main Authors: Déry, Stephen J., Stieglitz, Marc, McKenna, Edward C., Wood, Eric F.
• Format: Journal Article
• Language: English
• Published: Boston, MA American Meteorological Society 15.07.2005
• Subjects: Climate; Dams; Drains; Earth sciences; Earth, ocean, space; Exact sciences and technology; Flood peak; Fresh water; Freshwater; Hydrology; Hydrology. Hydrogeology; Latitude; Meltwater; Oceans; Outlets; River basins; River discharge; River flow; Rivers; Runoff; Runoff rates; Salinity; Salinization; Seasons; Snowmelt; Spring; Summer; Surface runoff; Upper ocean; Winter; James Bay; Canada; United States; North American Atlantic; North Atlantic; Hudson Bay; Northwest Atlantic; Eastern Canada; Ungava Bay; ANW, Atlantic, Labrador Current; PNW, Canada, Hudson Bay; Canada, Manitoba, Nelson R; ANW, Canada, Quebec, James Bay; Canada, Quebec, James Bay; Canada, Hudson Bay; ANW, Atlantic, Newfoundland Shelf; meltwater; drainage basins; time variations; hydrologic cycle; fresh-water environment; Atlantic Ocean; river discharge; snow; runoff; climate; North America; errors
• ISSN: 0894-8755; 1520-0442
• DOI: 10.1175/JCLI3440.1

The characteristics and trends of observed river discharge into the Hudson, James, and Ungava Bays (HJUBs) for the period 1964–2000 are investigated. Forty-two rivers with outlets into these bays contribute on average 714 km³ yr−1[= 0.023 Sv (1 Sv ≡ 10⁶ m³ s−1)] of freshwater to high-latitude oceans. For the system as a whole, discharge attains an annual peak of 4.2 km³ day−1on average in mid-June, whereas the minimum of 0.68 km³ day−1occurs on average during the last week of March. The Nelson River contributes as much as 34% of the daily discharge for the entire system during winter but diminishes in relative importance during spring and summer. Runoff rates per contributing area are highest (lowest) on the eastern (western) shores of the Hudson and James Bays. Linear trend analyses reveal decreasing discharge over the 37-yr period in 36 out of the 42 rivers. By 2000, the total annual freshwater discharge into HJUBs diminished by 96 km³ (−13%) from its value in 1964, equivalent to a reduction of 0.003 Sv. The annual peak discharge rate associated with snowmelt has advanced by 8 days between 1964 and 2000 and has diminished by 0.036 km³ day−1in intensity. There is a direct correlation between the timing of peak spring discharge rates and the latitude of a river’s mouth; the spring freshet varies by 5 days for each degree of latitude. Continental snowmelt induces a seasonal pulse of freshwater from HJUBs that is tracked along its path into the Labrador Current. It is suggested that the annual upper-ocean salinity minimum observed on the inner Newfoundland Shelf can be explained by freshwater pulses composed of meltwater from three successive winter seasons in the river basins draining into HJUBs. A gradual salinization of the upper ocean during summer over the period 1966–94 on the inner Newfoundland Shelf is in accord with a decadal trend of a diminishing intensity in the continental meltwater pulses.