Tidal Hydrodynamics in the Lower Columbia River Estuary through Depth Averaged Adaptive Hydraulics Modeling

Tate O. McAlpin,Gaurav Savant

doi:10.1155/2014/416914

Tate O. McAlpin, Gaurav Savant

Open Access

https://doi.org/10.1155/2014/416914

Copy DOI

Abstract

The adaptive hydraulics (AdH) numerical code was applied to study tidal propagation in the Lower Columbia River (LCR) estuary. The results demonstrate the readiness of this AdH model towards the further study of hydrodynamics in the LCR. The AdH model accurately replicated behavior of the tide as it propagated upstream into the LCR system. Results show that the MSf tidal component and the M4 overtidal component are generated in the middle LCR and contain a substantial amount of tidal energy. An analysis was performed to determine the causes of MSf tide amplification, and it was found that approximately 80% of the amplification occurs due to nonlinear interaction between the M2 and the S2 tidal components.

Highlights

A two-dimensional (2D) adaptive hydraulics (AdH) model was constructed to study tidal propagation through the Lower Columbia River (LCR) and the Willamette River systems
AdH results for the period of simulation were compared to the observed water surface elevations at several National Oceanic and Atmospheric Administration (NOAA) and United States Geological Survey (USGS) gages in the system (Figure 1)
A numerical model was validated to the tidal hydrodynamics in the Lower Columbia River estuary

Summary

Introduction

A two-dimensional (2D) adaptive hydraulics (AdH) model was constructed to study tidal propagation through the Lower Columbia River (LCR) and the Willamette River systems. As the tide progresses upstream, the transfer of energy from the lower harmonic components to the higher components occurs. A harmonic analysis of the model results and field observations was performed to ascertain the energy distribution; future analyses will include the velocity and discharge data available for this system. This harmonic analysis consisting of amplitudes as well as phases ensured that if the lower and higher harmonic constituents (overtidal components) are validated, the remaining energy in the water column must pass through as velocity head. Because the focus of this work was tidal propagation and not salinity propagation a three-dimensional (3D) analysis was not required

Model Description

Model Application History

Lower Columbia River Estuary

Mesh and Bathymetry

Period of Simulation and Boundary Conditions

Model Validation and Results

Analysis of Tidal Transformation

Conclusions