A study on the effects of dispersion coefficient on groundwater pollutant transport simulation

A comprehensive scientific analysis of temporal and spatial fluctuations of pollutants during the migration of groundwater is essential for precisely predicting their dispersion patterns and promoting rational regional development planning. In this research paper, a field radial dispersion test was conducted in decentralized drinking water sources downstream of the Fu Tuan River basin in Rizhao City, Shandong Province, China (FRSC). Chloride ion (Cl^-) solution was utilized as a tracer for the experiment. The longitudinal dispersion coefficient ( $a_L$ ) was determined by standard curve matching and using straight-line graphical methods. Additionally, the impact of $a_L$ on pollutant transport was investigated by creating the MT3DMS solute transport model with the help of GMS 10.4 software. The results indicate that the $a_L$ of the submerged aquifer varies depending on the distance from the source well in the main runoff direction. At distances of 10 and 15 m, the values of $a_L$ were observed to be 0.56 m and 0.88 m, respectively. Moreover, when these observed values of $a_L$ are used as simulation parameters in solute transport modeling on the same space-time scale, the hydrodynamic dispersion effect exhibited by the well is found to be weaker than the actual hydrodynamic dispersion effect.