PNNL-18484 Prepared for the U.S. Department of Energy under Contract DE-AC05-76RL01830 Puget Sound Dissolved Oxygen Modeling Study: Development of an Intermediate-Scale Hydrodynamic Model Z Yang T Khangaonkar R Labiosa T Kim November 2010 DISCLAIMER This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor Battelle Memorial Institute, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof, or Battelle Memorial Institute. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. PACIFIC NORTHWEST NATIONAL LABORATORY operated by BATTELLE for the UNITED STATES DEPARTMENT OF ENERGY under Contract DE-AC05-76RL01830 Printed in the United States of America Available to DOE and DOE contractors from the Office of Scientific and Technical Information, P.O. Box 62, Oak Ridge, TN 37831-0062; ph: (865) 576-8401 fax: (865) 576-5728 email: [email protected] Available to the public from the National Technical Information Service, U.S. Department of Commerce, 5285 Port Royal Rd., Springfield, VA 22161 ph: (800) 553-6847 fax: (703) 605-6900 email: [email protected] online ordering: http://www.ntis.gov/ordering.htm This document was printed on recycled paper. (9/2003) PNNL-18484 Puget Sound Dissolved Oxygen Modeling Study: Development of an Intermediate-Scale Hydrodynamic Model Z Yang T Khangaonkar R Labiosa T Kim November 2010 Prepared for The Washington State Department of Ecology Battelle—Pacific Northwest Division Richland, Washington 99352 Executive Summary Puget Sound is a large estuarine system bounded by 2,597 miles of complex shorelines and consists of several subbasins and many large estuaries with distinct properties. Pacific Ocean water enters Puget Sound and the Georgia Strait through the Strait of Juan de Fuca. Freshwater inflows to Puget Sound include 19 major rivers and multiple point and nonpoint sources including effluent discharges from industrial and municipal outfalls, agricultural runoff, and natural watershed runoff. Nutrient pollution is considered one of the largest threats to Puget Sound. There is considerable interest in understanding the effect of nutrient loads entering Puget Sound. The Washington State Department of Ecology contracted with Pacific Northwest National Laboratory to develop an intermediate-scale hydrodynamic and water quality model to study dissolved oxygen and nutrient dynamics in Puget Sound and to help define potential Puget Sound-wide nutrient management strategies and decisions. Specifically, the project is expected to help determine 1) if current and potential future nitrogen loadings from point and non-point sources are significantly impairing water quality at a large scale and 2) what level of nutrient reductions are necessary to reduce or control human impacts to dissolved oxygen levels in the sensitive areas. The development of a predictive nutrients and dissolved oxygen model of Puget Sound consists of two major components: 1) a three-dimensional coastal hydrodynamic model and 2) an off-line water quality model of Puget Sound. In this study, an intermediate-scale hydrodynamic model of Puget Sound was developed to simulate the hydrodynamics of Puget Sound and the Northwest Straits for the year 2006. The model was constructed using the unstructured Finite Volume Coastal Ocean Model - FVCOM. The average horizontal model grid resolution within Puget Sound in its present configuration is about 880 m. The model is driven by tides, river inflows, and meteorological forcing (wind and net heat flux) and simulates tidal circulation, temperature, and salinity distributions in Puget Sound. The model was calibrated against observed data of water surface elevation, velocity, temperature, and salinity at various stations within the study domain. Model calibration indicated that the model simulates tidal elevations and currents in Puget Sound reasonably well and reproduces the general patterns of the temperature and salinity distributions satisfactorily. The hydrodynamic model solutions have been generated for the year 2006 such that they may be used to drive the off-line water quality model based on CE-QUAL-ICM. One full-year model simulation requires about 34 hours in real time with 48 cores running in parallel mode on a 184-core computer cluster. iii Acronyms 2-D two-dimensional 3-D three-dimensional MAE mean absolute errors DFO Department of Fisheries and Oceans Canada Ecology Washington State Department of Ecology EPA U.S. Environmental Protection Agency FVCOM Finite Volume Coastal Ocean Model LIDAR light detection and ranging NARR North American Regional Analysis NAVD88 North American Vertical Datum of 1988 NCEP National Center for Environmental Prediction NOAA National Oceanic and Atmospheric Administration PSDEM Puget Sound Digital Elevation Model RME relative mean error RMSE root mean square error USGS U.S. Geological Survey UW University of Washington WSE water surface elevation XTide harmonic tide clock and tide predictor based on NOAA’s National Oceanic Service algorithms v Contents 1.0 Introduction .................................................................................................................................. 1-1 2.0 Hydrodynamic Model Setup ......................................................................................................... 2-1 2.1 Bathymetry Data .................................................................................................................. 2-3 2.2 Development of the Model Grid .......................................................................................... 2-3 2.3 Open Boundary Tides ........................................................................................................... 2-4 2.4 Open Boundary Salinity and Temperature Profiles ............................................................. 2-4 2.5 River Flows and Temperatures ............................................................................................ 2-13 2.6 Initial Conditions .................................................................................................................. 2-19 2.7 Meteorology Data ................................................................................................................. 2-19 3.0 Model Calibration ......................................................................................................................... 3-1 3.1 Introduction .......................................................................................................................... 3-1 3.2 Model Calibration – Water Surface Elevation ..................................................................... 3-2 3.3 Model Calibration – Tidal Currents ..................................................................................... 3-7 3.4 Model Calibration – Temperature and Salinity .................................................................... 3-15 4.0 Summary and Next Steps ............................................................................................................. 4-1 4.1 Summary .............................................................................................................................. 4-1 4.2 Model Limitation and Data Uncertainty .............................................................................. 4-1 4.3 Next Steps and Recommendations ....................................................................................... 4-2 5.0 References .................................................................................................................................... 5-1 vii Figures 1-1 Study Domain – Puget Sound, Strait of Juan de Fuca and Georgia Strait .................................. 1-2 2-1 Data Stations for Model Setup for Puget Sound, the Strait of Juan de Fuca, and Georgia Strait ............................................................................................................................................ 2-2 2-2 FVCOM Model Grid – Puget Sound, the Strait of Juan de Fuca, and Georgia Strait ................. 2-5 2-3 Model Grid for Admiralty Inlet and Whidbey Basin .................................................................. 2-6 2-4 Model Grid for Hood Canal and Central Sound.......................................................................... 2-7 2-5 Model Grid for South Puget Sound ............................................................................................. 2-8 2-6 Model Bathymetry – Puget Sound, the Strait of Juan de Fuca, and Georgia Strait .................... 2-9 2-7 Tidal Elevations at Open Boundaries Predicted by XTIDE ........................................................ 2-10 2-8 Temperature and Salinity Profiles at the Strait of Juan de Fuca Open Boundary ....................... 2-11 2-9 Temperature and Salinity Profiles at Georgia Strait Open Boundary ........................................