Services — Numerical Modeling RMA Bay-Delta model

The RMA Bay-Delta model is a well-established tool for analysis of the hydrodynamic and water quality impacts of proposed projects in the San Francisco Bay and Sacramento-San Joaquin Delta.

The RMA Bay-Delta Model was one of the primary tools used for the Bay Delta Conservation Plan (BDCP) evaluation of tidal marsh restoration and has been used extensively in the development of the Suisun Marsh Programmatic EIR/EIS.

Since 1996, the model has been used for analysis of:

  • Wastewater discharges, including dilution, dissolved copper and nickel, coliform, pathogens and nutrients
  • Levee failures (from single breaches to seismically induced delta-wide failures), their impact on water quality and Delta operations, and the effectiveness of emergency response measures
  • Tidal marsh restoration projects and their impact on hydrodynamics, tidal mixing and water quality in the Delta
  • Hydrodynamic and water quality impacts of Delta Cross Channel reoperation and installation of various gates and barriers throughout the Delta
  • Fish behavior based on flow, salinity and turbidity conditions
  • Flood events
  • Drought conditions
  • Nutrients and temperature
  • Sea level rise


Screenshot of Bay-Delta model tool simulation.

Model grid and bathymetry of the RMA Bay-Delta Model.

The RMA Bay-Delta Model accurately simulates of Delta-wide hydrodynamics and water quality transport.  In addition to standard water quality simulations, the model can be used in particle tracking mode to evaluate fish behavior or simulate the generation and dispersal of phytoplankton.

The RMA Bay-Delta Model utilizes the RMA2 hydrodynamics and RMA11 water quality transport finite element computational engines. The finite element model formulation allows use of an unstructured computation mesh where resolution can be increased locally to represent the topographic details of a restoration site. The RMA2 and RMA11 engines support combining 2D depth-averaged computational elements and 1D cross-sectionally averaged elements in a single mesh. In the RMA Bay-Delta Model, all large channels, embayments, and tidal marsh restoration areas are represented in 2D.

The RMA Bay-Delta Model does not directly simulate the effects of stratified flow, which would require application of a 3D model. The effects of stratification and gravitational circulation are approximated in the model through inclusion of a horizontal Richardson number and the calibration of mixing coefficients to best represent the observed salinity field for a historical period, or to best represent the computed salinity field from a 3D model simulation for a proposed condition.

Applications of the RMA Bay-Delta Model

ProjectProject PeriodClient
Particle Tracking Simulations Supporting USGS/Tamara Kraus’s Sac Regional Wastewater Hold Experiment and USGS Sampling Scheme2014USGS and Central Contra Costa Sanitary District
Dilution Analysis of Novato Sanitary District’s Proposed Discharge to Bel Marin Keys Unit V2014Novato Sanitary District and California State Coastal Conservancy
Numerical Modeling in Support of the 2014 California Drought Response2014State Water Contractors and Metropolitan Water District of Southern California
Dilution Analysis of Palo Alto Regional Water Quality Control Plant’s Discharge to South San Francisco Bay and Matadero Creek2013-2014City of Palo Alto
Numerical Modeling support for restoration studies in Suisun Marsh2013 California Department of Water Resources, Division of Environmental Services
Initial Modeling of Local and Regional Impacts of the Proposed Tule Red Tidal Marsh Restoration, Grizzly Island, California2013Westervelt Ecological Services
Hydrodynamic and particle track modeling in support of salmon out-migration studies2012-2014USBR and USGS
Incremental Impacts of Central Contra Costa Sanitary District’s Discharges to the San Francisco Bay-Delta System2012-2014Central Contra Costa Sanitary District
Analysis of Tidal Restoration of Prospect Island2011-2014California Department of Water Resources
Real-time modeling of Hydrodynamics, Salinity, Turbidity2010-2013Metropolitan Water District of Southern California
Delta Flood Modeling for the Central Valley Flood Protection Plan2010-2012California Department of Water Resources
Hydrodynamic and Salinity Impacts Modeling for Bethel Island, Horseshoe Bend - CalFed Levee Stability Program2010US Army Corps of Engineers Sacramento District
Delta Wetlands Particle Track Modeling for Island Diversion Alternatives2010Delta Wetlands
Far Field Dilution Analysis of the City of Modesto Water Quality Control Facility Discharge2010City of Modesto
RMA Particle Track Modeling of Fish Screen Alternatives for Existing Delta Export Facilities2010MWH
Water Quality Impacts of Pinole-Hercules Water Pollution Control Plant Discharge in San Pablo Bay2009City of Pinole
Numerical Modeling of the WERF Wet Weather Blending Project Discharges to San Francisco Bay2009East Bay Municipal Utilities District
Impacts of Delta Diablo and Central Contra Costa Sanitary Districts Waste Water Recycling on Salinity Concentrations in San Francisco Bay2009Delta Diablo Sanitary District and Central Contra Costa Sanitary District
Franks Tract-Three Mile Slough Pilot Project2008-2013 California Department of Water Resources, USBR
Hydrodynamic, Salinity, and Particle Transport simulations for analysis of the proposed “Two-Gates” pilot project2008-2011Metropolitan Water District of Southern California
Water Quality Impacts of Delta Diablo Sanitation District Discharge in New York Slough and at Nearby Water Intakes2008-2009Delta Diablo Sanitation District
Numerical Modeling of Central Contra Costa Sanitary District Discharge in San Francisco Bay2008Central Contra Costa Sanitary District
2-D Hydrodynamics for Ship Simulation Studies2008US Army Corps of Engineers San Francisco District
2-Dimensional Modeling in support of the Bay Delta Conservation Plan2007-present SFWCA, California Department of Water Resources
Habitat Management, Preservation, and Restoration Plan for Suisun Marsh Programmatic EIR/EIS2006-2010California Department of Water Resources
Delta Risk Management Strategy (DRMS) – modeling of multiple levee breach scenarios in the Delta2006-2009California Department of Water Resources
Delta Modeling Support for Delta Cross Channel reoperation, Through Delta Facility analysis, and Franks Tract alternative analysis2006-2008California Department of Water Resources
Numerical Modeling of Delta Levee Breach Scenarios with Emergency Response2006-2007Metropolitan Water District of Southern California
Jones Tract Levee Breach Simulation2006California Department of Water Resources
Near and Far Field Dilution Analysis of the Manteca Wastewater Discharge2005-2006City of Manteca
CALFED Flooded Islands Study – analysis of opportunities to manage tidal mixing in and near Delta flooded islands2004-2006CALFED
Numerical Modeling of Discovery Bay2004-2006Reclamation District No. 800
CALFED Levee Risk Assessment - preliminary modeling of large scale flooding of the Delta due multiple levee breaches2003-2004CALFED
Mathematical Modeling of Hydrodynamic and Water Quality Impacts of the Tule Belle Micro-tidal Restoration Project2002CALFED Suisun Marsh Levee Investigation Team
Evaluation of the EBMUD Discharge to Central San Francisco Bay2001East Bay Municipal Utilities District
Mathematical Modeling of Hydrodynamics and Water Quality Impacts of Suisun Marsh Levee Breaches1999CALFED Bay-Delta Program
Impacts of the BADA Discharges on Copper Levels in the San Francisco Bay1998Bay Area Dischargers Association
Evaluation of the City of Palo Alto Treated Wastewater Discharge to South San Francisco Bay1997City of Palo Alto
Evaluation of Novato Sanitary District Treated Wastewater Discharge to San Pablo Bay1996Novato Sanitary District