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ESTIMATING NITROGEN AND TIDAL EXCHANGE IN A NORTH PACIFIC ESTUARY WITH EPA'S VISUAL PLUMES PDSW MODEL
Citation:
Frick, W E., A C. Sigleo, AND D T. Specht. ESTIMATING NITROGEN AND TIDAL EXCHANGE IN A NORTH PACIFIC ESTUARY WITH EPA'S VISUAL PLUMES PDSW MODEL. Presented at 3rd International Conference on Marine Waste Water Discharges, Catania, Italy, September 25-October 2, 2004.
Impact/Purpose:
A main objective of this task is to combine empirical and physical mechanisms in a model, known as Visual Beach, that
â— is user-friendly
â— includes point and non-point sources of contamination
â— includes the latest bacterial decay mechanisms
â— incorporates real-time and web-based ambient and atmospheric and aquatic conditions
â— and has a predictive capability of up to three days to help avert potential beach closures.
The suite of predictive capabilities for this software application can enhance the utility of new methodology for analysis of indicator pathogens by identifying times that represent the highest probability of bacterial contamination. Successful use of this model will provide a means to direct timely collection of monitoring samples, strengthening the value of the short turnaround time for sampling. Additionally, in some cases of known point sources of bacteria, such as waste water treatment plant discharges, the model can be applied to help guide operational controls to help prevent resulting beach closures.
Description:
Accurate assessments of nutrient levels in coastal waters are required to determine the nutrient effects of increasing population pressure on coastal ecosystems. To accomplish this goal, in-field data with sufficient temporal resolution are required to define nutrient sources and sinks, and to ultimately calculate nutrient budgets. Very high temporal resolution data, however, can capture transient events and document unexpected short-term temporal processes. The interpretation of these high density data sets, however, may require complex models. The application of the U.S. EPA Visual Plumes PDSW model output suggests estuarine plumes carry estuarine effluent well offshore, playing an important role in the exchange of estuarine and coastal water. In contrast, evidence is found that internal tides, if present, play a lesser, effectively supporting, role in explaining the variation in water properties near estuaries.