Modeling the transport and distribution of fecal coliform in a tidal estuary.

A laterally averaged two-dimensional fecal coliform transport model incorporated into hydrodynamic and salt modules was developed to simulate the fate and transport of fecal coliform in the tidal Danshui River estuary of northern Taiwan. We validated the developed model with measured data, including longitudinal velocity, salinity, and fecal coliform concentration, collected in 2000. The simulated results of current, salinity, and fecal coliform concentration quantitatively agreed well with the measured data. The model sensitivity analysis indicated that the mortality rate plays an important role in the distribution of fecal coliform concentrations along the tidal Danshui River estuary to Tahan Stream. The validated model was applied to investigate the effects of different freshwater discharges at upstream boundaries on the distributions of fecal coliform. The results revealed that low freshwater discharge resulted in a higher fecal coliform concentration at upstream reaches but had little influence on the downstream of the estuary.