Difference Modeling of Stream Pollution

Finite-difference methods are developed for the numerical analysis of BOD and dissolved oxygen profiles confined to cases which may be treated as one-dimensional problems. Temporal and spatial variations of hydraulic parameters and sources and sinks of BOD and dissolved oxygen can be incorporated into the models developed. Results obtained by the methods developed compare favorably to the results of available analytical solutions. For estuaries, the methods are applicable to the analysis of the variations of BOD and dissolved oxygen profiles within a tidal cycle. Significant variations of these profiles from those obtained by the commonly used quasi steady-state approach are demonstrated. The spreading which results from the tidal velocity variation is shown to have a significant effect on the BOD and dissolved oxygen profiles. The methods developed should prove useful in studies of estuaries in which the tidal variations are large and the temporal variations in the strengths of the BOD and dissolved oxygen inputs are great.