Modelling faecal bacteria pathways in receiving waters Available to Purchase

The two-dimensional finite-volume model ‘Hemat’ was refined to model the pathways, fate and decay factors of faecal indicator organisms for an integrated river and coastal basin water system. The numerical model was developed, calibrated and tested by modelling faecal indicator organism inputs from river sources. A comprehensive field data set was available including intensive offshore survey data collected during a two-week period; these were used as a time series for the verification of the hydrodynamic model. River discharges and water quality data were used as boundary and initial conditions for the model. The impact of alternative land-use management strategies on the water quality of the receiving estuarine and coastal waters was investigated by modelling a series of 14 scenarios. Generally, the model results show that the faecal indicator organism input from point sources of sewage effluent dominated during dry weather and base flow conditions. On the other hand, riverine sources (such as diffuse catchment sources) significantly dominated the concentrations in the bay both during and after rainfall events. Finally, it was found that a reduction in land used for animal husbandry can considerably reduce the critical peak concentration occurring after heavy rainfall events.