Author(s): L. Brice; C. Yarko Niño; M. CristiaN. Escauriaza

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Keywords: Well-mixed estuary; baroclinic flow; Rio Maipo; MUSCL-Hancock solution; saline intrusion

Abstract: Strong advective flows in well-mixed estuaries can produce abrupt fronts and density gradients, which cause secondary circulation and affect the ecosystem by generating recirculation or accumulation of pollutants inside the estuary. To model these complex phenomena, a method capable of adequately representing the dynamics of the flow by considering the salt as an active tracer, influencing the transport within the estuary, is required. A numerical model based on the finite volume MUSCL-Hancock method is used to solve the shallow-water flow equations in combination with an advection/diffusion of salt equation, to simulate two-dimensional unsteady flow in a vertically well-mixed estuary. The salt transport equation is coupled to the momentum equations via the hydrostatic term, which permits simulation of baroclinic secondary circulation. A series of benchmark test problems are used to validate the model and demonstrate its capabilities. The model is then used to simulate the saline intrusion within the Rib Maipo estuary, a well-mixed tidal river in central Chile. The numerical results predict that the presence of a littoral bar at the river mouth precludes the upstream transport of salt, resulting in an almost negligible salinity intrusion in the system. This result is validated with field measurements of salinity, taken from within the estuary.

DOI: https://doi.org/10.1080/00221680509500130

Year: 2005