The PULSEQUAL Model: Using Combinations of Simple Mathematical Equations to Evaluate Complex Storm Effects on Water Quality

by John K. Marr, Limno-Tech Inc., Arbor, United States,
Robert Eimstad, Limno-Tech Inc., Arbor, United States,

Document Type: Proceeding Paper

Part of: Water Management in the '90s: A Time for Innovation


Storm discharges (stormwater and combined sewer overflows) have transient and highly variable impacts on receiving waters. Simple water quality equations have been developed to accurately model storm impacts without resorting to complex mathematical formulations. The model (called PULSEQUAL) features a user-friendly environment to model the water quality effects of dozens of outfalls over extremely long periods of record. This provides information, including the expected magnitude, duration and frequency of water quality problems, which can be used to control alternatives. Examples are provided for recent studies on the Lower Willamette River in Oregon and the St. Joseph River in Indiana. The complexities of storm-related water quality effects often drive engineers and analysts to choose very complex methods and models to evaluate river conditions and the benefits of controls. Unfortunately, complex models often only increase the level of precision achieved but not the accuracy of model forecasts. Also, these complex approaches are costly, data intensive, and often have limited flexibility to address the many diverse combinations of river flows and rainfall conditions.

Subject Headings: Water quality | Mathematical models | Stormwater management | Water discharge | Model accuracy | Rivers and streams | Mathematics | United States | Oregon | Indiana

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