ABSTRACT
The model referred to above is an assembly of concepts in the form of one or more mathematical equations that approximate the behavior of a natural system or phenomenon. The seaward end of an estuary is easily defined because it is connected to the sea. The landward end, however, is not that well defined. Generally, tidal influence in a river system extends further inward than salt intrusion. The variations in an estuary throughout the year, together with the fact that each estuary is different, make modeling rather difficult. The transmission of waterborne diseases has been a matter of concern for many years. The impact of high concentrations of disease-producing organisms on water uses can be significant. The problems of DO in surface waters have been recognized for over a century. The impact of low Dissolved Oxygen (DO) concentrations or of anaerobic conditions was reflected in an unbalanced ecosystem, fish mortality, odors, and other aesthetic nuisances.
