The James River has the strongest and most persistent classical estuarine circulation among the major tributary estuaries of the Chesapeake Bay system. The strong exchange flow transports huge amounts of the cleaner lower Bay water into the bottom waters of the Lower James. This results in the James having the rarest occurrence of hypoxic conditions among the Chesapeakey Bay major tributary estuaries. In addition to this strong circulation, there is an extensive topographic eddy controlling the lateral circulation in the Lower James River and the Hampton Flats. The interaction of this lateral circulation and a topographically arrested estuarine front, located offshore of Newport News Point, contributes to the success of seed oyster beds in the tidal James. Recent observations show that this eddy, together with transport between the lower James and Elizabeth River, results in a phytoplankton bloom in the lower James after the bloom develops in the Lafayette River. Numerical model studies of circulation, transport processes, and exhanges between estuary-subestuary are discussed. Two timescales are introduced to diagnose the competition between vertical mixing and gravitational circulation and their impact on the dissolved oxygen level in deep waters. Coupling with a biochemical timescale of oxygen consumption, the hypoxic conditions in deep waters may be successfully interpreted with the relative magnitudes among the timescales. The sea-level rise and its potential impact on salinity inside the James River are also discussed.

Dr. Jian Shen received his Master's and Ph.D. degrees in Marine Science from the Virginia Institute of Marine Science (VIMS) of the College of William and Mary. He then served as a Senior Environmental Engineer at Tetra Tech, Inc. in Fairfax, VA for five years, where he primarily conducted research on watershed model development and three-dimensional numerical modeling of eutrophication and toxic transport processes in estuaries, lakes, and rivers. In 2002, he returned to VIMS to serve on the faculty of the Physical Sciences Department and now serves as a Research Associate Professor. His research includes estuarine circulation, water quality and eutrophication modeling, storm surge simulation, and data assimilation. Specific interests include biochemical and physical coupling in estuarine and coastal environments, inverse modeling of water quality in estuaries, and transport timescales of estuarine processes.

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