The Effect of Changing Sediment Supply on Sedimentation in a Glacier-Fed Lake

Abstract

Bow Lake, Alberta, Canada, is a deep, thermally stratified alpine lake fed by an overland meltwater stream from Bow Glacier. The glacier has been generally receding from its Neoglacial maximum, and around 1955 a pond began to form at the terminus. Prior to pond development, sedimentation in Bow Lake was dominated by underflows which formed thick varves in the lower areas of the lake floor. Since 1955, however, the pond has deprived the stream of much of its sediment load, and inflows are now dispersed through the lake mainly as rightward-deflected interflows moving above the hypolimnion. The effect of the pond, therefore, has been to alter the pattern of sedimentation in the lake as well as to reduce its overall rate of deposition.