Effects of the hydroelectric developments on the oceanographic surface parameters of Hudson Bay

Abstract

A one‐dimensional oceanic mixed‐layer model was used to simulate the annual surface layer properties of Hudson Bay. The model reproduces the sparse available data well and shows the equal importance of seasonal ice cover and run‐off on the pycnocline pattern. In spring, the large freshwater input from run‐off and local ice melt followed by summer heating slows the deepening of the pycnocline depth by wind mixing. As these stabilizing effects decrease and the wind strength increases, the pycnocline depth increases in the fall and continues to increase in the winter when the salt rejection effect during ice growth replaces the cooling effect. In the spring the salt rejection reduces and run‐off increases; the large pycnocline depth cannot be maintained and a shallow pycnocline is formed, starting a new seasonal cycle.

When the run‐off cycle includes the effects of hydroelectric developments, the results indicate that a new shallow surface pycnocline is formed earlier in the spring. This causes a decrease in surface layer temperature and salinity, thus stimulating more ice growth. On the other hand, in the summer the surface layer salinity is higher and the temperature lower. This decreases the stability, thus further deepening the pycnocline and increasing the deviations from normal conditions.