River-Induced Transport in Kootenay Lake

Abstract

A series of dye-tracer experiments was performed in and around a river plume in Kootenay Lake, British Columbia. River and stream inflows are often considered to be a method of nutrient or waste introduction and 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 scales are likely to differ greatly from those that might be attributed to average flow conditions in the absence of detailed observations. The observed presence of velocity shears associated with wind stress, river inflow, and basin geometry suggests that the phenomenon of shear dispersion augments the stirring action of local turbulence. The densimetric Froude number indicates that the river behaves as a mixing layer and values of the apparent horizontal diffusion coefficient in and near the river plume are of the order of 2–5 m