Simulation of coastal water pollution with fuzzy parameters

Randomly changing values in time and space of different parameters such as pollutant load sources and physico-chemical coefficients, is the main difficulty in water pollution modeling. Deterministic modeling is not adequate because introduces crisp values of these parameters. To tackle the problem, fuzzy set theory is applied to define imprecise parameters which are used in a water pollution model. Physico- chemicals coefficients and pollutant load sources are expressed in the form of fuzzy numbers. A two-dimensional finite element algorithm combined with fuzzy arithmetic is used for the solution of the advection-dispersion equation for the BOD parameter. A characteristic-Galerkin scheme is also used in order to reduce the numerical diffusion due to the convective term. This model is applied for the study of pollutant transport in the Gulf of Thermaikos located in Northern Greece.