Study of Tidal Propagation in the Lower Columbia River (LCR) Estuary using Numerical Modeling

A numerical model Adaptive Hydraulics (AdH) was utilized to study the propagation of tides in the LCR estuary. Model results and observations show that the symmetric tide at the inlet rapidly degenerates as the tide propagates upstream due to shallow water, friction and riverine influences. At the inlet M2 is the major tidal component however, upstream energy is progressively transferred from the M2 and other primary components to the MSf, M4 and S4 components, with a majority of the energy passing to the MSf component. An analysis was performed to determine the mechanism of this transfer and it was found that the nonlinear interactions between the M2 and S2 components due to the shallow water effects causes ~80% of the transfer. The presentation will demonstrate the model, results from the model, a detailed description of the tide in the LCR estuary and the analysis of tidal behavior.