Dispersion in Ice-Covered Lakes

Dispersion studies in three ice-covered lakes are presented. One of the lakes has a large river through-flow. In the other two lakes, small seiche-induced currents are generated through wind action on the ice cover. Dispersion coefficients are computed from five dye experiments lasting from ½ day to 16 days. These coefficients are related to measured current velocities. The turbulence in the river-flow dominated lake is found to be very low with disperision coefficients less than 1 cm²/s in directions transverse to the flow. In the lakes where the turbulence is generated by shear from the seiche-induced currents the horizontal dispersion coefficients are two orders of magnitude higher, being almost as high as in ice-free lakes.