Modeling of Circulation and Dispersion in Coastal Lagoons

A review of strategies to model the circulation and pollutant transport in inletcoastal lagoon systems is presented. Simplified procedures based on correlation analysis, analytic solutions to the ordinary linearized differential equation describing the system, and a numerical model that solves the governing equation for multi-inlet, multi-basin systems are described. The models predict the inlet flow characteristics, basin surface elevation response, and pollutant concentrations for cases where the basin responds in a simple pumping or Helmholtz mode. To describe circulation and pollutant movement when the pumping mode assumption is inappropriate two-dimensional, vertically-averaged models based either on finite element or finite difference solution methodologies are presented. This approach is also employed when the specific interest is circulation or pollutant transport within the basin. A unique hybrid model, coupling a one dimensional inlet model with a two-dimensional, vertically-averaged model for the basin, is described. The use of boundary fitted coordinate models is explored exploiting their ability to accurately describe areas with disparate spatial scales. A procedure is presented to assist in model selection for inlet-lagoon systems. To demonstrate model application for management decision making a simplified approach is applied to predict the impacts of inlet channel modification on the circulation, flushing dynamics, and salinity in the Charlestown, R.I. pond system. © 1994 Elsevier Science B.V