Simulation of bromide transport in a layered aquifer using two-dimensional and three-dimensional computer models

Simulation of a two-well tracer test at a site near Mobile, Alabama was performed and compared with the experimental breakthrough curve. The models used to simulate the test results were the three-dimensional USGS code HST3D and the two-dimensional USGS code MOC. The results of the three-dimensional model were also compared with the results of the two-dimensional model.;The three-dimensional model HST3D predicted the measured breakthrough curve accurately with the exception of early arrival times of the tracer in the withdrawal well. The two-dimensional model MOC did not accurately predict the bromide concentration in the withdrawal well during the two-well test. When the dispersivity was increased forty-fold, the MOC results approximated the measured breakthrough curve.