Date Awarded


Document Type


Degree Name

Doctor of Philosophy (Ph.D.)


Virginia Institute of Marine Science


Destratification in the York River, USA, during high spring tides is the result of the interruption of normal two-layer estuarine flow by advection of relatively fresh water in to the River mouth from the Chesapeake Bay. This is due to the presence of a longitudinal salinity gradient in the Bay and a difference of tidal current phase between the River and the Bay. Similar behavior is seen in other subestuaries of the Chesapeake Bay and may be common in subestuary-estuary interactions. Correlation and regression analysis are used to examine relationships between stratification variation in the lower York River and a variety of tidal and environmental parameters. A gross measure of stratification was derived from near surface and deep salinity samples. One hundred fifty six observations were made over a 434 day period from February 1982 to April 1983. The environmental and tidal factors evaluated were assessed on a daily basis and incorporated a variety of transformations. The factors included wind speed and direction, fresh water river flow from both the York and Rappahanock Rivers, water temperature, mean sea level and the following tidal parameters: observed and predicted daily mean and maximum high and low tide height, flood, ebb, and combined flood and ebb tidal ranges for Gloucester Point and for Hampton Roads. The results indicate that: (1) almost all of the tidal range or high tide height factors tested are equally strongly correlated with salinity difference, being associated with as much as 48% of the variation in that value; (2) that a combination of functions of tidal range and mean sea level at Gloucester Point are associated with more than 70% of the variation; and (3) that with the addition of wind stress terms as much as 80% of the variation can be included in the model. Over a range of observed salinity differences from 0.01 to 11.06 per mille the 25 term model predicts a range of -1.01 to 11.09 per mile with a root mean squared error of 0.99 per mile. A model predicting variation in surface mixed layer depth from salinity difference is also presented.



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