Modeling and Validation of Coastal Wastewater Effluent Plumes Using High-Resolution Nonhydrostatic Regional Ocean Modeling System
A wastewater pipe module is developed and implemented into a high-resolution, nonhydrostatic circulation model, the Regional Ocean Modeling System (ROMS). Intermediate and far field dilution and plume rise height is validated to cross flow laboratory experiments of Roberts, Snyder, and Baumgartner. The domain and diffuser is modeled after Southern California Bight (SCB) discharge regions with idealized flat bottom topography, linearly density-stratified vertical profile, and uniform current to mimic laboratory setup in a scaled-up domain. Direct Froude number comparisons are made. Buoyant plume flow regimes are accurately reproduced, and dilution metrics are reasonably predicted for low Froude numbers (i.e., F ≤ 1). High Froude numbers require more distance away from pipe for accurate plume characteristics. Generally, low cross flow velocity simulations, consistent with typical SCB coastal currents, are reasonably well-resolved using the 3 meter nonhydrostatic ROMS model. High Froude number flows may require effluent input parameterization adjustment or additional spatial resolution.