Simulation of Solute Transport in a Finite Aquatic Ecosystem Using the Two-Dimensional Advection-Dispersion Equation in Cylindrical Coordinates: Analysis of the Impact of Emergent and Rigid Vegetation

Aquatic porous media experience the intrusion of pollutants from natural or anthropogenic sources, affecting the health of aquatic ecosystems. The retention and diffusion of pollutants strongly depend on parameters such as vegetation volumetric fraction (φ), porosity, and medium density. This study numerically solves the advection-dispersion equation in cylindrical coordinates using finite difference methods to evaluate pollutant concentration profiles in an initially contaminated aquatic porous medium, where flow velocity and dispersion coefficient vary with the vegetation fraction. The results reveal a marked sensitivity of concentration profiles to an increase in vegetation fraction, which reduces pollutant diffusion, while higher porosity promotes their dispersion. Furthermore, zones of high-medium density accumulate more pollutants, increasing local concentrations. These interactions influence aquatic ecosystems, with elevated concentrations potentially disrupting flora and fauna. This study highlights the importance of considering these parameters to develop effective strategies for the management and preservation of aquatic environments.