1. Operational Environmental Prediction: Nearshore Water Quality in the Great Lakes
David J. Schwab
NOAA Great Lakes Environmental Research Laboratory
Ann Arbor, MI

2. Climate – Meteorology – Hydrology – Hydrodynamics – Biology/Chemistry
Factors Contributing to Nearshore Water Quality in the Great Lakes
Climate – Meteorology – Hydrology – Hydrodynamics – Biology/Chemistry

3. Beach Closings or HABs Forecasting Meteorology Meteorology
Change in Land-use
Change in Land-use
Change in Land-use
Hydrology/Water Flow
Bacterial Fate
Hydrology/Water Flow
Bacterial Fate
Beach Closings
Circulation and
Bacterial Fate
Circulation and
Bacterial Fate

4. Outline
Lake Michigan tributary modeling using nested-grid hydrodynamic models - application to beach water quality forecasting
Lake Erie coupled physical/biological model - application to HAB and hypoxia forecasting

5. Beach Closures
Major health risk of microbial contamination by bacteria, viruses and protozoa in recreational waters
E.Coli requires a 24 hour incubation period
People may unintentionally swim in contaminated water

7. Lake Michigan Beach Quality Forecasting
Lakewide grid
(POM model)
Coupled models
nested grids +
Burns Ditch nested model grid

8. Princeton Ocean Model (Blumberg and Mellor, 1987)
- Fully three-dimensional nonlinear Navier-Stokes equations
- Flux form of equations
- Boussinesq and hydrostatic approximations
- Free upper surface with barotropic (external) mode
- Baroclinic (internal) mode
- Turbulence model for vertical mixing
- Terrain following vertical coordinate (<sigma>-coordinate)
- Generalized orthogonal horizontal coordinates
- Smagorinsky horizontal diffusion
- Leapfrog (centered in space and time) time step
- Implicit scheme for vertical mixing
- Arakawa-C staggered grid
- Fortran code optimized for vectorization
Application to the Great Lakes
- No open boundary
- No tides
- Uniform salinity
- Seasonal thermal structure
- Uniform rectangular grid
- XDR used for input and output
Nested grid considerations:
3d boundary condition for u, v, and T interpolated from coarse grid at each boundary point
Vertically integrated velocity is specified for external mode
Internal mode velocity and temperature are specified from 3-d boundary condition for inflow, use radiation condition for outflow
Water level is adjusted to maintain zero mean in nested grid subdomain

9. Nested grid hydrodynamic models in Lake Michigan

10. Burns Ditch 100m computational grid
24 km
6 km

11. Web site: www.glerl.noaa.gov/res/glcfs/bd

16. Great Lakes Coastal Forecasting System - Operational Nowcast
20 day sample using vertically averaged currents

17. Lake Erie Coupled Physical/Biological model

18. The Problem:
- Excessive nutrient loading in the 1960’s led to massive algal blooms, oxygen depletion, and diminished water quality in Lake Erie.
Water Quality Agreement between the US and Canada limited P loads from municipal, industrial, and agricultural sources.
- With controls, P levels decreased to acceptable levels and water quality improved.
- In recent years, P levels in Lake Erie appear to be increasing, despite controls.

19. The Problem:
- Excessive nutrient loading in the 1960’s led to massive algal blooms, oxygen depletion, and diminished water quality in Lake Erie.
Water Quality Agreement between the US and Canada limited P loads from municipal, industrial, and agricultural sources.
- With controls, P levels decreased to acceptable levels and water quality improved.
- In recent years, P levels in Lake Erie appear to be increasing, despite controls.
Our Approach:
- Incorporate phosphorus transport and fate dynamics into high resolution (hourly time scale, 2 km horizontal resolution) hydrodynamic model of Lake Erie as a first step toward spatially explicit model of entire lower food web

20. Lake Erie Physical Characteristics:
Surface Area: km2 Throughflow ~ 6000 m3s-1
Volume: 480 km3 Retention time: 2.5 yrs
Mean Depth: 18.6 m

21. Ecosystem Forecasting of Lake Erie Hypoxia
What are the Causes, Consequences, and Potential Remedies of Lake Erie Hypoxia?
Linked set of models to forecast:
changes in nutrient loads to Lake Erie
responses of central basin hypoxia to multiple stressors
P loads, hydrometeorology, dreissenids
potential ecological responses to changes in hypoxia
Approach
Models with range of complexity
Consider both anthropogenic and natural stressors
Use available data – IFYLE, LETS, etc.
Will assess uncertainties in both drivers and models
Apply models within an Integrated Assessment framework to inform decision making for policy and management
What are the Causes, Consequences, and Potential Remedies of Lake Erie Hypoxia?
We propose to develop a linked set of models to forecast changes in nutrient loads to Lake Erie, responses of central basin hypoxia to those changes, and potential ecological responses to changes in hypoxia.
Models with range of complexity
Consider both anthropogenic and natural stressors
Will assess uncertainties in both drivers and models
Apply models within an Integrated Assessment framework to inform decision making for policy and management

22. Hypoxia Forecasting Modeling Approach
Model ranging in complexity
Correlation-based models
1D hydrodynamics with simple mechanistic WQ model
Vertical profiles extracted from full hydrodynamic model
TP, Carbon, Solids
3D hydrodynamics with simple mechanistic WQ model
Physics from full hydrodynamic model
3D hydrodynamics with complex mechanistic WQ model
WQ framework similar to Chesapeake Bay ICM model
Multi-class phyto- and zooplankton, organic and inorganic nutrients, sediment digenesis, etc
Addition of zebra mussels and other improvements

23. Chapra, S.C. 1980. J. Great Lakes Res. 6(2):101-112.

24. Effect of Phosphorus Controls on Lake Erie Central Basin Springtime P Concentration (Ryan et al., 1999)

25. D. Rockwell, US EPA - GLNPO

26. Lake Erie 1994 physical/biological model
Hydrodynamics
- Great Lakes version of POM
20 vertical levels, 2 km horizontal grid (~6500 cells)
Hourly meteorology (1994, JD 1-365)
Realistic tributary flows
Accounts for ice cover
Mass balance for P
POM hydrodynamics (2d for now)
Realistic P loading
Constant settling velocity (for now)

27. Computer animation of model results:
Starts in January, 1994
Uses 2d currents from hydrodynamic model
Time dependent P loads
Combination Lax-Wendroff and upwind advection scheme
No horizontal diffusion
Initial condition: C = 10 ug/L
Settling velocity = 6.8E-7 m/s (21 m/yr)

28. Questions?