Discontinuous Galerkin modeling of the Columbia River's coupled estuary-plume dynamics

Discontinuous Galerkin modeling of the Columbia River's coupled estuary-plume dynamics

Vallaeys, Valentin (Université Catholique de Louvain)
Kärnä, Tuomas (Oregon Health and Science University)
Delandmeter, Philippe (Université Catholique de Louvain; Universiteit Utrecht)
Lambrechts, Jonathan (Université Catholique de Louvain)
Baptista, António M. (Oregon Health and Science University)
Deleersnijder, E.L.C. (TU Delft Mathematical Physics; Université Catholique de Louvain)
Hanert, Emmanuel (Université Catholique de Louvain)

2018

The Columbia River (CR) estuary is characterized by high river discharge and strong tides that generate high velocity flows and sharp density gradients. Its dynamics strongly affects the coastal ocean circulation. Tidal straining in turn modulates the stratification in the estuary. Simulating the hydrodynamics of the CR estuary and plume therefore requires a multi-scale model as both shelf and estuarine circulations are coupled. Such a model has to keep numerical dissipation as low as possible in order to correctly represent the plume propagation and the salinity intrusion in the estuary. Here, we show that the 3D baroclinic discontinuous Galerkin finite element model SLIM 3D is able to reproduce the main features of the CR estuary-to-ocean continuum. We introduce new vertical discretization and mode splitting that allow us to model a region characterized by complex bathymetry and sharp density and velocity gradients. Our model takes into account the major forcings, i.e. tides, surface wind stress and river discharge, on a single multi-scale grid. The simulation period covers the end of spring-early summer of 2006, a period of high river flow and strong changes in the wind regime. SLIM 3D is validated with in-situ data on the shelf and at multiple locations in the estuary and compared with an operational implementation of SELFE. The model skill in the estuary and on the shelf indicate that SLIM 3D is able to reproduce the key processes driving the river plume dynamics, such as the occurrence of bidirectional plumes or reversals of the inner shelf coastal currents.

Columbia River estuary
Multi-scale model
Plume dynamics
River-to-ocean continuum
Unstructured mesh

http://resolver.tudelft.nl/uuid:54526582-bcc9-4c2d-bbf4-945f3be14508

https://doi.org/10.1016/j.ocemod.2018.02.004

2019-11-01

1463-5003

Ocean Modelling, 124, 111-124

Accepted Author Manuscript

Institutional Repository

journal article

© 2018 Valentin Vallaeys, Tuomas Kärnä, Philippe Delandmeter, Jonathan Lambrechts, António M. Baptista, E.L.C. Deleersnijder, Emmanuel Hanert