Abstract:
Morphometric, hydrologic, and climatic data for Lake Winnipeg and its watershed are given. Over half the annual water supply to the lake comes from eastern Precambrian Shield rivers, which drain only 18% of the total lake watershed. Prairie rivers (which drain sedimentary watersheds), have lower discharges of water, but carry high concentrations of nutrients, salts, and sediments. Theoretical water renewal time for the lake varied from 2.9 to 4.3 years for 1969-1974, depending upon seasonal variations in river discharge. Theoretical water renewal time for the south basin of Lake Winnipeg was computed t be 0.4 to 0.8 years, but interbasin water fluxes due to wind-driven currents are much larger than river discharge into this small basin. With large fetch, abundant wind energy, and shallow water depths, the lake is well mixed vertically. Large horizontal gradients for most limnological parameters were related to the orientation, magnitude, dissolved salt and suspended sediment load of river discharge into the three major basins of the lake.
