Two‐Dimensional Mass Transport in Estuaries

Abstract

On a tidally averaged basis, the two‐dimensional estuarine circulation is characterized by a horizontal seaward velocity in the upper layer and a landward velocity in the lower layer, with a compensating vertical velocity to maintain hydraulic continuity. A relatively simple method of analysis is developed for this type of circulation from the hydrodynamic equations of momentum, continuity, and state. It is based on the condition that the salinity distributions in both the longitudinal and vertical directions are known or may be assigned. In addition to an analytical solution for the horizontal and vertical velocities, the analysis generates the values of vertical eddy viscosity which characterizes the vertical exchange of momentum, an important process of circulation in partially mixed estuaries. Successful applications of the analysis to a number of estuaries throughout the country prove that the present method is efficient and simple to use. The present method of analysis offers a definite advantage as a first approximation to this type of estuarine circulation.