Numerical simulation of BOD5 dynamics in Igap\'o I lake, Londrina, Paran\'a, Brazil: Experimental measurement and mathematical modeling

The concentration of biochemical oxygen demand, BOD5, was studied in order to evaluate the water quality of the Igap\'o I Lake, in Londrina, Paran\'a State, Brazil. The simulation was conducted by means of the discretization in curvilinear coordinates of the geometry of Igap\'o I Lake, together with finite difference and finite element methods. The evaluation of the proposed numerical model for water quality was performed by comparing the experimental values of BOD5 with the numerical results. The evaluation of the model showed quantitative results compatible with the actual behavior of Igap\'o I Lake in relation to the simulated parameter. The qualitative analysis of the numerical simulations provided a better understanding of the dynamics of the BOD5 concentration at Igap\'o I Lake, showing that such concentrations in the central regions of the lake have values above those allowed by Brazilian law. The results can help to guide choices by public officials, as: (i) improve the identification mechanisms of pollutant emitters on Lake Igap\'o I, (ii) contribute to the optimal treatment of the recovery of the polluted environment and (iii) provide a better quality of life for the regulars of the lake as well as for the residents living on the lakeside.