Hydrodynamic and water quality modelling: An experience

The three-dimensional numerical model LMT3D, used in simulations of water quality in coastal seas and lakes, is presented along with a description of the basic equations and the accompanying numerical methods. The model is composed of a hydrodynamic module and of a mass-transport module. Methodology for coupling these two modules into an integrated water quality model is described, the main problem in this coupling being the different time and space scales of both modules. Several methods for diminishing the numerical diffusion of the hybrid finite volume numerical scheme used in the model are described. Some experience with several practical applications of the model in water quality problems in lakes and in coastal seas is also presented. Three case studies from this field are described in more detail in the companion paper (Rajar, Cetina and Sirca, 1997).