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PREDICTING THE BUILDUP OF POLLUTANT CONCENTRATIONS USING EPA'S VISUAL PLUMES MODEL
Citation:
Frick, W E. PREDICTING THE BUILDUP OF POLLUTANT CONCENTRATIONS USING EPA'S VISUAL PLUMES MODEL. Presented at Estuarine Research Federation Meeting, St. Petersburg, FL, November 4-8, 2001.
Impact/Purpose:
Produce a computer model utilizing water transport estimates or real-time current-meter data to track the motion of contaminants from point and other sources, and to predict the concentration of pathogens or other pollutants at beach and other sensitive sites.
Description:
Anthropogenic sources contribute pollutants to estuaries that are significantly influenced by tides, frequently exhibiting velocity reversals. Flow reversals, even in the absence of diffusion, can cause a buildup of pollution from a particular discharge in the receiving water. On the flood, the receiving water is loaded with pollutants as it passes over the source and moves upstream. On the ebb tide, it passes over the discharge a second time. If the freshwater flow is small compared to the tidal flow, the process repeats several times and raises the ambient background pollution above the prevailing levels due to other sources or natural processes.
The U.S. EPA's Visual Plumes model offers a way to estimate the buildup of background pollution from this process if the estuary is reasonably one-dimensional in character. The general approach is simple, ignoring dispersion and the effect of the channel details, except at the source. Besides describing source variables and physical conditions, such as ambient density stratification, input is limited to defining the cross-sectional area of the channel at the point of discharge and the water velocity as a function of time. The theory is described and examples of the technique are presented.