THE INFLUENCE OF LAKE MORPHOMETRY ON SEDIMENT FOCUSING

Sediment focusing is a process whereby water turbulence moves sedimented material from shallower to deeper zones of a lake. Sediment focusing occurs in lakes in both the erosional (coarse-grained sediments) and the transportational zone with the latter characterized by discontinuous sedimentation and resuspension. The zone of accumulation is defined as the zone where sedimentation is final (i.e. no resuspension) and where there is no further sediment focusing. A geochemical tracer (Pb) was used to trace sediment focusing patterns in 12 lakes of different morphometries. The area occupied by the zone of accumulation is predicted from the mean basin slope (alpha'(p)) with 86% of the variance explained. Only in large, exposed lakes in which turbulence from waves is more severe are the resulting sediment distributions more erratic. This study is the first to provide a general model of sediment focusing patterns among lakes.