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Using a composite grid approach in a complex coastal domain to estimate estuarine residence time

John C. Warner·W. Rockwell Geyer·Herman G. Arango
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Abstract

We investigate the processes that influence residence time in a partially mixed estuary using a three-dimensional circulation model. The complex geometry of the study region is not optimal for a structured grid model and so we developed a new method of grid connectivity. This involves a novel approach that allows an unlimited number of individual grids to be combined in an efficient manner to produce a composite grid. We then implemented this new method into the numerical Regional Ocean Modeling System (ROMS) and developed a composite grid of the Hudson River estuary region to investigate the residence time of a passive tracer. Results show that the residence time is a strong function of the time of release (spring vs. neap tide), the along-channel location, and the initial vertical placement. During neap tides there is a maximum in residence time near the bottom of the estuary at the mid-salt intrusion length. During spring tides the residence time is primarily a function of along-channel location and does not exhibit a strong vertical variability. This model study of residence time illustrates the utility of the grid connectivity method for circulation and dispersion studies in regions of complex geometry.

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John C. Warner, W. Rockwell Geyer, Herman G. Arango. 2010. Using a composite grid approach in a complex coastal domain to estimate estuarine residence time. https://doi.org/10.1016/j.cageo.2009.11.008

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