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Title: Horizontal transport induced by upwelling in a canyon-shaped reservoir Authored by: Okely, P.N. and Imberger, J. Abstract:
Several processes associated with spatial variations in buoyancy flux and mixing set up local and lake-wide horizontal temperature gradients that in turn drive slow gravitational currents. These motions can dominate the horizontal transport and re-distribution of biological and chemical material. Here intrusions, indicative of horizontal transport, are identified in field data from a small drinking water reservoir and the origin and character of the flows were investigated using the three-dimensional (3D) hydrodynamic Estuary Lake Coastal Ocean Model (ELCOM). It is shown that a horizontal temperature gradient is set up along the surface layer, due to upwelling bringing the metalimnion closer to the surface towards the upwind region, leading to a spatial variation in entrainment and surface cooling. The flows that are driven by these gradients form significant mass flux paths, enhancing exchange with the boundaries and controlling the fate of upwelled fluid. Further, the interaction of the currents with other hydrodynamic conditions is explored; namely the interaction with surface wind-driven currents, and the influence of different internal seiches generated by alternative lake bathymetries.
Reference: Okely, P.N. and Imberger, J., 2007, Horizontal transport induced by upwelling in a canyon-shaped reservoir, 586 (1):343-355 Keywords: Lake - Horizontal transport - Upwelling - Differential deepening - Convective circulation - Internal seiche |
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