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Modeling Workgroup

Scope and Purpose

The Chesapeake Bay Program integrated models include simulations of the airshed, watershed, estuary, living resources, and climate change. These integrated models assess effects of current and proposed watershed management on changes in nutrient and sediment loads delivered to the Bay, and the effect those changing loads have on water quality and living resources. The CBP Models assist CBP decision-makers in estimating the collective actions needed to achieve State and Federal water quality standards necessary to restore the Bay.


  • Develop cutting-edge and technically defensible modeling tools as directed by CBP decision-makers.
  • Develop airshed, watershed, estuary, living resource, and climate change scenarios as directed by CBP decision makers.
  • Estimate the aggregate effect of management practices from each source sector due to changes in land use, atmospheric deposition, fertilizer application, animal populations, manures, and management actions.
  • Track and quantify nutrient and sediment loads as implementation progresses in the Watershed Implementation Plans (WIPs) towards the 2025 goal to have all management measures in place to achieve the Chesapeake living resource based water quality standards.
  • Develop scenarios to assess management actions needed to fully achieve Bay water quality standards that are cost effective, equitable through a dialog with CBP decision-makers.

Overall CBP Model Framework

The CBP model framework is designed to address questions of how Chesapeake Bay water quality will respond to changes in watershed and airshed management actions.  In the first step of model scenario development, scenario management actions are interpreted by several models, including the Land Use Change Model, the Airshed Model, and Scenario Builder to produce input to the Watershed Model, as shown in the figure below.  The CBP Land Use Change Model, predicts changes in land use, sewerage, and septic systems given changes in land use policy. The Airshed Model, a national application of Community Multiscale Air Quality Model (CMAQ), predicts changes in deposition of inorganic nitrogen due to changes in emissions. The Scenario Builder software combines the output of these models with other data sources, such as the US Census of Agriculture, to generate inputs to the Watershed Model.  The Phase 5.3 Watershed Model predicts the loads of nitrogen, phosphorus, and sediment that result from the given inputs.The estuarine Water Quality and Sediment Transport Model (WQSTM) (also known as the Chesapeake Bay Model) predicts changes in Bay water quality due to the changes in input loads provided by the Watershed Model. As a final step, a water quality standard analysis system examines model estimates of DO, chlorophyll, and water clarity to assess in time and space the attainment of the Bay living resource-based water quality standards.


Additional information can be found at:

  • Lee Currey (Co-Chair), Maryland Department of the Environment
  • Dave Montali (Co-Chair), West Virginia Department of Environmental Protection
  • Lewis Linker (Coordinator), U.S. Environmental Protection Agency
  • Amanda Pruzinsky (Staff), Chesapeake Research Consortium

  • Mark Bennett, U.S. Geological Survey (USGS)
  • Steve Bieber, Metropolitan Washington Council of Governments
  • Bill Brown, University of Delaware Cooperative Extension
  • Arthur Butt, Virginia Department of Environmental Quality
  • Monir Chowdhury, District of Columbia Department of the Environment (DDOE)
  • Robin Dennis, U.S. Environmental Protection Agency National Oceanic and Atmospheric Administration (NOAA)
  • Steve Gladding, New York State Department of Environmental Conservation
  • Bill Keeling, Virginia Department of Environmental Quality
  • Ross Mandel, Interstate Commission on the Potomac River Basin (ICPRB)
  • George Onyullo, District of Columbia Department of the Environment (DDOE)
  • Gary Shenk, U.S. Environmental Protection Agency
  • Helen Stewart, Maryland Department of Natural Resources
  • Peter Tango, U.S. Geological Survey (USGS)
  • Ted Tesler, Pennsylvania Department of Environmental Protection
  • Harry Wang, Virginia Institute of Marine Science (VIMS)

Evaluation of Multiple Shallow-water Systems Analysis

The U.S. Environmental Protection Agency’s (EPA) Chesapeake Bay Program Office (CBPO) is working with principal investigators (PIs) to provide the Chesapeake Bay Program (CBP) partners with proposals for the application of shallow-water models to improve Chesapeake Bay shallow-water simulations of dissolved oxygen, chlorophyll a, suspended solids, and water clarity in order to better understand the impacts of alternative management strategies on water quality and living resources in the tidal Chesapeake Bay. The RFPs cover the evaluation of the multiple, developed shallow-water models. Over the course of the two-year project, multiple modeling teams will be funded to apply different shallow-water models using common forcing conditions over a three– to five–year-base-case run at specified shallow-water sites. EPA will also fund an independent model evaluation team that will use state-of-the-art metrics to assess the relative skill of these shallow-water models based on available CBP water quality and submerged aquatic vegetation (SAV) monitoring data. The independent model evaluation team will also compare the results from a series of nutrient and sediment change scenarios and analyze causes and impacts of differences among the shallow-water models. Applicants may apply for either or both activities, but EPA will fund successful applicants for one activity or the other, not both.

The CBP partners include federal agencies, the seven Chesapeake Bay watershed jurisdictions, and many non-federal organizations; however, work funded under this RFP will support the seven watershed jurisdictions and other non-federal partners. The seven watershed jurisdictions are Delaware, the District of Columbia, Maryland, New York, Pennsylvania, Virginia, and West Virginia.

Shoreline Sensitivity Scenario SENS148 - 50% reduction in bank solids loads:

Peer Reviews

CMAQ Review Process: During the past three years, CMAS, in collaboration with EPA scientists, has organized two CMAQ review panel meetings etc. The first CMAQ review meeting was held during December 2003. The second meeting was held during May 2005. The review process usually starts by inviting a number of key scientists to participate in the process. The scientists are selected based on their expertise in accordance with the focus of the review session. After reviewing numerous reports and articles and completing their meeting in Research Triangle Park, North Carolina, the review panel prepares a comprehensive report on their findings and recommendations. EPA then responds to the comments of the reviewers. Final review reports are posted below.

Chesapeake Bay Watershed Model

  • Phase 4.3 Watershed Model Calibration
  • Scenario Data

FINAL Water Quality Model Calibration Run January, 2002

Shoreline Sensitivity Scenario Tier III p20

Tier 3 plus 20% reduction in bank solids and nutrient loads (20% reduction from year 2000 bank loads):

Shoreline Sensitivity Scenario SENS147

100% Reduction in bank loads of solids with no nutrients reduction:

Shoreline Sensitivity Scenario SENS146

100% Reduction in bank loads of solids, 100% reduction in bank loads of nutrients:

Shoreline Sensitivity Scenario SENS153 -Final Calibration with Refined SAV Simulation:

2002 Chesapeake Bay Water Quality Model

All of the files below are in the pdf format. To download your free Adobe Acrobat Reader visit www.adobe.com


Chesapeake Bay Program Community Models - The Chesapeake Bay Program develops and maintains several environmental models that enable scientists to simulate changes in an ecosystem due to changes in population, land use or pollution management. Used properly, these models can help restoration leaders develop policies and programs to improve the quality of the Bay.

Peer Review Guidance

The CBP models follow the peer review guidance developed by EPA’s Science Advisory Board (SAB) for regulatory models: http://www.epa.gov/spc/pdfs/modelpr.pdf  and the peer review guidance developed by the Ecological Society of America and endorsed by the American College of Preventive Medicine, American Fisheries Society, American Institute of Biological Sciences, American Public Health Association, American Society of Agronomy, American Society of Limnology and Oceanography, Association of Teachers of Preventive Medicine, Crop Science Society of America, Ecological Society of America, Estuarine Research Federation, Institute of Food Technologists, Soil Science Society of America, Society for Conservation Biology

Shoreline Sensitivity Scenario Tier III

Tier III reductions in solids and nutrient loads (including year 2000 bank load controls):

Shoreline Sensitivity Scenario SENS149 - 20% reduction in bank solids loads:

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