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Development and Validation of the Water Quality Model System for Massachusetts Coastal Waters
PI: Changsheng Chen, Univ. of Massachusetts - Dartmouth, Robert Beardsley, Univ. of Massachusetts - Dartmouth
Project Number:2010-R/RC-116Start Date:2010-02-01End Date:2012-07-31
Objectives: We propose to develop a water quality assessment and forecast model under the framework of the Northeast Coastal Ocean Forecast System (NECOFS) for Massachusetts coastal waters (hereafter referred to as Mass Waters) including Mass Bay, Cape Cod (CC) Bay, Boston Harbor, Nantucket Sound/Shoals, Vineyard Sound, and Buzzard Bay. This project meets the MIT Sea Grant Implementation Plan 2009-2013 in a focus area of health coastal ecosystem: HCE 1: Develop scientific information to support ecosystem-based approaches to managing the coastal environment. The HydroQual Row-Column Advanced water quality model (RCA) has been used for water quality assessment in Massachusetts and Cape Cod Bays (Mass/CC Bays) during the last decade as part of the Massachusetts Water Resource Authority (MWRA) Mass Bay outfall monitoring program. Under MWRA contract, we have converted RCA into an unstructured-grid finite-volume version (UG-RCA) and coupled it to the Finite-Volume Coastal Ocean Model (FVCOM). Driven by FVCOM, UG-RCA is being used to assess water quality (especially DO concentration and harmful algal bloom conditions) in Mass/CC Bays for 2008. The objectives of this proposed research are to 1) implement UG-RCA into NECOFS and place it into continuous ecosystem forecast operation for the Mass Waters’ domain; 2) use UG-RCA to conduct a hindcast simulation to build the ecosystem database for use by coastal zone management and other environmental planners and decision-makers; 3) improve the predictive capability of UG-RCA by assimilation of in-situ data collected using fixed (moorings) and moving (routine survey) platforms using Ensemble Kalman Filter (EKF) methods and compare and validate existing and new adaptive sampling schemes for data assimilation and optimal design of water quality observing infrastructure; and 4) conduct process-oriented modeling experiments to examine the roles of long-term secular (climate change-induced) and short-term (daily to monthly) physical and biological processes and their highly nonlinear interaction on water quality and harmful algal blooms in Mass Waters.
Methodology: With MIT Sea Grant support, we have developed an integrated model system for the Massachusetts coastal region (called Mass Coastal FVCOM) as a nested component in a regional-domain Gulf of Maine/Georges Bank/New England Shelf (GoM/GB/NES) FVCOM system. The core of this model system is Mass Coastal FVCOM, which features a high-resolution (10 to 500 m) unstructured grid in the horizontal and a terrain-following coordinate (41 layers) in the vertical to provides accurate geometric fitting of the complex irregular coastline and bathymetry in Mass Waters. The Mass Coastal FVCOM was implemented into NECOFS and placed in forecast operation in April 2009. We have recently developed the following suite of ecosystem/water quality models as part of the FVCOM system: 1) the Generalized Biological Module (GBM) that allow users to select either a pre-built biological model (such as NPZ, NPZD, etc) or construct their own biological model using the pre-defined pool of biological variables and parameterization functions; 2) UG-RCA, which we converted directly from the structured-grid RCA (version 3) for Mass/CC Bays developed by HydroQual; 3) FVCOM-WQM, a water quality model based on the EPA Water quality Analysis Simulation Program (WASP); and 4) an unstructured-grid finite-volume version of CE-QUAL-ICM, the Army Corps of Engineers structured-grid water quality box model. Among these ecosystem models, RCA has been well calibrated and used for the Mass/CC Bays water quality assessment since 2001. With MWRA support, we parallelized UG-RCA, so it can be run simultaneously together with FVCOM with parallelization (“online” mode) or driven separately by FVCOM output (“offline” mode). UG-RCA has been validated by detailed comparison with the water quality measurement data collected in 2006-2007, and is now being used to assess water quality conditions and harmful algal bloom events during 2008. Building on our successful development of NECOFS, we propose to implement UG-RCA into NECOFS and set up it in an “online” forecast mode to serve as one of the ecosystem forecast components for use by MWRA, NMFS, coastal zone management, and the research community. Driven by the Mass Coastal FVCOM hindcast output generated using data assimilation, we will also set up UG-RCA in an “offline” mode to build the resulting model-data integrated ecosystem database. This 3-D multiyear time series database will greatly help government and academic researchers and managers in making strategic or emergency decisions on efficient utilization of limited marine resources, in evaluating and monitoring water quality and predicting its trends, and in protecting the coastal and estuarine environments in Massachusetts coastal waters.
Rationale: Long-term records show a significant regional warming tendency in Mass Waters. For example, annual mean water temperature in Woods Hole has warmed at an average rate of +0.04 oC/year since 1970 (Nixon et al, 2004). This warming tendency has in turn altered the coastal environment by contributing to a shift in timing of the peak abundance of residence marine species, more frequent occurrence of hypoxia in the bays during summer, a dramatic decrease of commercial fishery stocks (such as winter flounder), and increased occurrence of harmful algal blooms (HABs) in Massachusetts Bay and Nantucket Sound/Shoals. It seems clear that a better understanding of this complex ecosystem and ability to predict both short- and long-term changes due to natural and human-induced causes are needed to better manage local marine resources. Because this ecosystem is characterized by complex nonlinear interactions between physical, biological and chemical processes that vary significantly in time and space, it will be difficult to understand solely through in-situ measurements which are inherently limited in time and space. We think it is imperative that we develop a fully 3-D prognostic ecosystem model system that can help synthesize in-situ and satellite-based measurements and provide research and management communities with accurate ecosystem hindcasts and forecasts that they can use to better understand and manage our marine resources. NECOFS is an operational forecast system that is capable of predicting the physical environment in Mass Waters. Adding a tested ecosystem model component into NECOFS meets the goal of the MIT Sea Grant strategic plan for ecosystem model development and application. This system also can be used for the spatially explicit integrated ecological economic decision support.
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