RIVER-INDUCED TRANSPORT IN KOOTENAY LAKE

A series of dye-tracer experiments was performed in and around a river plume in Kootenay Lake, British Columbia. River and stream inflows ar e often considered to be a method of nutrient or waste introduction an d dispersal; in this paper we show that they can be unpredictable and highly variable in their behavior over short time scales. Consequently , diffusivities observed over small length scales and short time scale s are likely to differ greatly from those that might be attributed to average flow conditions in the absence of detailed observations. The o bserved presence of velocity shears associated with wind stress, river inflow, and basin geometry suggests that the phenomenon of shear disp ersion augments the stirring action of local turbulence. The densimetr ic Froude number indicates that the river behaves as a mixing layer an d values of the apparent horizontal diffusion coefficient in and near the river plume are of the order of 2-5 m(2)s(-1) and the dispersion i n the direction of the river inflow is separated from the transverse t urbulent diffusion.