In this project, the P.I. will develop an unsteady (time-dependent) generalization of a steady-state layer model of estuary plumes. The objective is to study the mechanisms responsible for observed complex horizontal flow structure of these plumes, which is likely due to their nonlinear dynamics, and which is not addressable by the existing model. Specific topics include: 1. nonlinear adjustment of a buoyant fluid in a channel; 2. evolution of an estuarine plume and its response to variable discharge, ambient flow, and wind stress; 3. the effect of coastal geometry on coastal currents; and, 4. effects of coastal geometry on marine layer jets.