Mathematical Modelling of the Fraser River Plume

Abstract

Abstract The Fraser River forms a well-defined layer of brackish water in the Strait of Georgia, with associated strong surface currents and salinity contrasts between it and the much deeper underlying waters. The numerical solution of a rotating, non-linear, reduced gravity, vertically integrated, upper layer model to describe the motion of this large river plume is described. Results from extensive field observations including tracking of surface drifters and CTD surveys are used to adjust and verify the model. Comparisons of observed and computed velocity and salinity fields show that the model simulates well the dominant flow patterns of the plume. A hindcast of two time periods in June and November 1986 is presented. Both hindcasts were characterized by periods of calm winds as well as the passage of reasonably intense storms, so that the response of the plume to wind forcing, as distinct from the wind-free situation, was quite well delineated.