Slack Tide Oxygen Balance Model

Abstract

A mixed segment slack tide oxygen balance model is used to compute BOD/DO concentrations in a heavily polluted tidal estuary. The usual Streeter-Phelps assumptions are adopted for aerobic conditions, while the rate of deoxygenation is assumed to be supply-limited under anoxic conditions. A subtle computational difficulty is revealed by applying the model in connectionwith a prototype pollution study. Under serious pollution conditions, the desired quasi-steady water quality response for a given tidal state, hydrographic condition, and pollution input may not be obtainable from the governing steady-state equations. However, the correct solution can always be found from an equivalent time-dependent oxygen balance model. The computational procedure outlined herein is generally applicable to slack tide water quality models.