ABSTRACT
This chapter presents a brief review of the most basic physical processes controlling the residual nontidal circulation in a partially mixed estuary. It discusses the interactions between the nontidal velocity field and the salinity distribution, and the residual circulation without considering details in the characteristics of the tidal motion. Pritchard described the basic dynamics and kinematics of partially mixed estuaries as represented by the Chesapeake Bay and its tributary estuaries in Maryland and Virginia. From his analysis of salinity observations in the James River estuary, Pritchard showed that the salt balance in a coastal plain estuary is maintained primarily by a longitudinal advective salt flux and a vertical nonadvective salt flux. Pritchard showed that the primary longitudinal force balance was between pressure gradient, the vertical gradient in turbulent stress, and tidal acceleration, although the tidal acceleration term was of only secondary importance.
