Seasonal Climatology of Tidal Non-Linearities in a Shallow Estuary
Hourly sea levels recorded over a 16-month period at eight tide gauges throughout the estuarine system at Murrells, South Carolina, clarify the climatology of tidal distortion within this shallow, well-mixed estuary. Numerical results are consistent with these data and suggest comparable behavior in other geometrically-similar systems. The non-linear tidal response to changes in the amplitude-to-depth ratio (a/h) are investigated utilizing the spring-neap cycle over a single month and the offshore steric response over an entire year or more. As a/h increases in Murrells estuary due to greater tidal amplitude, tidal distortion becomes more flood dominant. However, patterns of non-linear tidal distortion in response to lower frequency ocean level change are strongly dependent upon proximity to local concentrations of intertidal flats. In areas of small tidal flat extent, as a/h decreases (due to rising sea level), tidal distortion becomes less flood dominant; in areas of extensive flats, absolute distortion and, therefore, flood dominant nature grows with greater h. Numerical modeling of estuary sea height and tidal velocity support the observations, which are consistent with the hypotheses of Aubrey and Speer (1985) and Speer and Aubrey (1985). They also have implications for changes in estuarine response to accelerated sea-level rise in the near future.
KeywordsTidal Flat Tidal Channel Tidal Amplitude Garden City Tidal Height
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