Development of Chesapeake Bay Program’s Phase 7 Water Quality Bay Model

As the largest estuary in the United States, Chesapeake Bay’s ecosystem health is important both ecologically (for the wildlife) and economically (for the fishing industry and coastal community). The Virginia Institute of Marine Science (VIMS) is leading the development of EPA’s next-generation management model for the estuarine portion of the Bay, known as the Phase 7 Main Bay Model (MBM) based on the unstructured-grid model, SCHISM (schism.wiki). In this presentation, we will discuss the motivation for the Phase 7 MBM development and the progress made over the past three years. The MBM domain includes the entire bay and all its tributaries, along with a large portion of adjacent coastal ocean. We will present the linkage of MBM to watershed, airshed and ocean, as well as the changes of these drivers under climate changes. The water quality model (ICM) for the bay is fully coupled with hydrodynamic model, wave model and sediment transport model. ICM also comprises many sub-models for sediment nutrient diagenesis, submerged aquatic vegetation (SAV), wetland, oyster and pH, etc. It can simulate many water quality parameters such as chlorophyll-a (CHL-A), carbon, nitrogen, phosphorus and dissolved oxygen (DO), and living resources in shallow waters that impact water quality. To build a robust and reproducible modeling system, we have significantly restructured the code and the entire workflow, the latter based on a user-friendly python-based interface. In addition, we have developed many easy-to use pre/post-processing, visualization and diagnostic tools. Comprehensive model assessment is an on-going process and we will present the spatiotemporal variations of key variables like dissolved oxygen (DO) and chlorophyll-a (CHL-A), as well as the lessons we have so far learned from the development of MBM and future plans. The flexibility of the MBM provides significant advantages for holistic decision making across multiple scales (from pelagic to shallow embayment).

Presentation Preference: Oral

Primary Presenter: Zhengui Wang, Virginia Institute of Marine Science (wangzg@vims.edu)

Authors:

Joseph Zhang, Virginia Institute of Marine Science  (yjzhang@vims.edu)

Jian Shen, Virginia Institute of Marine Science  (shen@vims.edu)

Wenfan Wu, Virginia Institute of Marine Science  (wwu@vims.edu)

Lewis Linker, U.S. EPA Chesapeake Bay Program Office  (linker.lewis@epa.gov)

Richard Tian, U.S. EPA Chesapeake Bay Program Office  (rtian@chesapeakebay.net)

Carl Cerco, Arlluk Technology Solutions, LLC  (carlcerco@outlook.com)