Modelling enteric bacteria level in coastal and estuarine waters

Details are given in this paper of the development of a numerical model for describing the bacterial transport processes in estuarine and coastal waters. The transport of enteric bacteria is influenced by many physical, chemical and biological factors, including both the suspended and bed sediments. In recent years, an increasing number of studies have shown that generally the sediments contain much higher bacterial population levels than previously assumed. The aim of this study has been to develop a numerical modelling tool for predicting the sediment-linked bacterial concentration levels in coastal and estuarine waters. This paper outlines the theoretical background of an enteric bacterial water quality numerical model. A conceptual model has been established for representing the transport of bacteria due to sediment movement, including deposition and suspension. Details are given of the solute and mass transport equations used to simulate the flow and transport of suspended sediments and enteric bacterial indicators. The enteric bacteria transport equation includes enhanced source and sink terms to represent bacterial kinetic transformation and disappearance or reappearance due to sediment deposition or resuspension. The model has been applied to the turbid water environment in the Bristol Channel and Severn estuary, UK, with initial results from the modelling study being presented.