Mathematical simulation of transport of sediment and kepone in the James River estuary

Abstract

The mathematical simulation of sediment and Kepone (a highly chlorinated pesticide) transport in the James River estuary was conducted by applying the sediment and contaminant transport model, FETRA, to an 85-km river reach between Bailey and Burwell Bays. The FETRA code is an unsteady, two-dimensional, finite model, utilizing the Galerkin weighted residual method. The model consists of three submodels coupled together to take into account sediment-contaminant interaction. the submodels are: (1) sediment transport model, (2) dissolved contaminant transport model, and (3) particulate contaminant (contaminants adsorbed by sediment) transport model. Transport of sediment and particulate contaminants is simulated for each sediment type or size fraction. The FETRA code was applied to simulate the migration of sediment and Kepone for three river discharges. Tidally influenced depth and velocity distributions in the study area were obtained by the unsteady, one-dimensional code, EXPLORE. These results were used by the two-dimensional code, FETRA, to obtain longitudinal distributions of sediment and Kepone. Hence, the results presented here are cross-sectionally averaged values changing with tidal flow. Comparison of computed results and field data for both sediment and Kepone concentrations indicates very good agreement, confirming the validity of the model. Mathematical simulation of Kepone transport under most probable flow conditions yields an estimate of 89.1 kg/yr of Kepone transported seaward from Burwell Bay. Of this 89.1 kg of total Kepone, 25.3% is carried by sediment, while 74.7% is in a dissolved phase.