The Dynamics and Exchange Flow Variability of the Coos Estuary
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Date
2019-01-11
Authors
Conroy, Ted
Journal Title
Journal ISSN
Volume Title
Publisher
University of Oregon
Abstract
Many estuaries have large variability in salinity structure due to variable river discharge, having the potential to induce large seasonal changes in estuarine exchange flow. In this study, a numerical ocean model of the Coos Estuary, Oregon, is developed and used to examine the variability of the estuarine exchange flow. The exchange flow is driven by tidal processes and is strongly modified by the strength of the tidal forcing: a higher exchange of volume and salt occurs during the larger amplitude fortnightly spring tides. This forcing maintains a persistent exchange flow with constant periodicity year-round, although the hydrography of the estuary is highly seasonal. The geometry of the estuary, composed of a dredged main channel and multiple connecting tributaries, significantly influences the dynamics of the estuary, including the length of the salinity intrusion, the importance of tidal timescale correlations between velocity and salinity, and freshwater advection throughout the estuary.