Study of influence of diffusive and advective models for the dispersion of pollutants on River Paraibuna

Abstract

Incidents involving dumping of pollutants into water are becoming more and more frequent, making it important to study new methods in order to develop strategies to predict these episodes and mitigate their damage to nature and human life. The present work aims to make a comparison between one-dimensional models of diffusion and advection for a dispersion of pollutants using the Paraibuna river as an application example, with the purpose of discussing and exploring the characteristics of each model. For this purpose, it was used the GILTT (Generalized Integral Laplace Transform Technique) method and the Taylor method in order to solve the diffusive model and the Separation of Variables method with Laplace Transform for solving the advective model. Pollutant dispersion simulations are presented for each methodology and the results are discussed and compared with actual observed data obtained in the literature. Results show that in the advective model, the pollutant wave remains compacted throughout the whole process, revealing a good approximation of the moment at which occurs the highest concentration in a fixed position; on the other hand, in the diffusive model, it is noticeable that in both approaches the amount of pollutant is higher at locals near the source of injection, taking some noticeable time for its dilution, revealing how the molecular diffusion process occurs inside the pollutant wave. It was possible to conclude that each model provides satisfactory information that meets the theoretical expectations for the dispersion of pollutants and that the methodology used was practical and effective for the purposes of this work.