Dispersion of active pollutants in a shallow sea

Abstract

Shallow coastal seas are the "priviledged" places for the dumping of wastes of all kinds: sewage, mud re leases, and chemical refuses are typical examples. In most cases, the shallow coastal seas are therefore very polluted. This paper describes a digital simu lation of the diffusion and transportation of pollu tants released in the shallow sea bordering Belgium. The model of course has much wider application. The principal new development in this paper is the method of integration of equations which describe such systems. The equations of the model have dominant advection terms, mixed derivatives, and nonlinear interaction terms, and are solved by a special predictor- corrector scheme consisting of three distinct steps. The mixed derivative is separated into second deri vatives along the grid axes and an auxiliary axis. The first two steps (implicit and locally one-dimen sional) form the predictor. The third one is the corrector, and it yields a consistent discrete approximation of the time derivative. The accuracy is 0(τ2 + τh + h2). A stability condition is derived and some problems in implementing the method are discussed. The paper concludes by presenting the results of a simulation of pollutant dumping in the North Sea near Ostend.