| Fecal coliform is the one of the most widely used indicator microorganism to monitor the pathogens in surface waters. Fecal coliform exist in both free-swimming and particle-associated states. Environmental factors such as solar radiation, pH, salinity, and temperature are the most important factors affecting the die-off of fecal coliform. In addition to advection and diffusion, fecal coliform may swim actively toward certain gradients in the water column and sediment bed.; To improve the understanding of the dynamics of fecal coliform and to provide a flexible and reliable model to assist water quality management, a fate and transport model of fecal coliform bacteria was developed in this study. The new model was developed using the Environmental Fluid Dynamics Code (EFDC) as the basic framework. It performs hydrodynamics and sediment transport computations. The effect of solar radiation, dissolved oxygen, temperature, pH, and salinity was incorporated into the model. The developed model is able to simulate the fecal coliform in both free-swimming and particle-associated states on a time-variable basis.; The developed model has been applied to the Tidal Basin and the Washington Shipping Channel using the field data. Model results demonstrate the significance of the impact of sediment transport under various flow conditions. The model results also confirm that the sediment bed is capable of storing a large amount of fecal coliform. In addition, settling and active movement of fecal coliform in the water column may play an important role when the die-off rate of fecal coliform is low. |
