Progress in Implementing the EPA WASP Model for Narragansett Bay

Lucner Charlestra1, Edward Dettmann2

1Postdoc., USEPA, Atlantic Ecology Div., charlestra.lucner@epa.gov2USEPA, Atlantic Ecology Div., dettmann.edward@epa.gov

CHRP-EPA Modeling WorkshopJuly 7, 2015

Presentation Outline

• Introduction

• Linkage between hydrodynamic and water quality models

• WASP input data

• Simulation results

• Summary/Discussion

2

Introduction

Acknowledgments: Bob Ambrose, Tim Wool, Chris Knights, Jim Hagy Mohamed Abdelrhman, Jason Grear, Hal Walker, Brenda Rashleigh

EPA and CHRP models differ in approach Model segmentation scheme Time step Equation formulation Our model includes organic as well as inorganic N and P

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Model Linkage

4

5

Linkage between Hydrodynamic and Water Quality Models

EFDC

Hyd File

WASP

Environmental Fluid Dynamics Code (EFDC) provides hydrodynamics, temperature, salinity

EFDC output is stored for use by WASP

WASP calculates water quality using EFDC output and biochemical kinetics

Model Grid

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WASP Model Domain:

• 661 segments per layer• 8 Water column layers

(sigma grid)

• 5288 segments total

Segment size is variableTypical segment size:• 640 m east-west• 1220 m north-south EFDC only

Model State Variables

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Ammonia Nitrogen (mg N L-1) Detrital Phosphorus (mg-P L-1)

Nitrate Nitrogen (mg N L-1) Detrital Silica (mg Si L-1)

Dissolved Organic Nitrogen (mg N L-1) Total Detritus (mg DW L-1)

Inorganic Phosphate (mg P L-1) Salinity (ppt)

Dissolved Organic Phosphorus (mg-P L-1) Benthic Algae (g DW m-2)

Inorganic Silica (mg Si L-1) Periphyton Cell Quota Nitrogen (mg N gDW-1)

Dissolved Organic Silica (mg Si L-1) Periphyton Cell Quota Phosphorus (mg P gDW-1)

CBOD1 (ultimate) (mg O2 L-1) Inorganic Solids 1 (mg DW L-1)

CBOD2 (ultimate) (mg O2 L-1) Inorganic Solids 2 (mg DW L-1)

CBOD3 (ultimate) (mg O2 L-1) Inorganic Solids 3 (mg DW L-1)

Dissolved Oxygen (mg O2 L-1) Phytoplankton 1 (mg Chl a L-1)

Detrital Carbon (mg C L-1) Phytoplankton 2 (mg Chl a L-1)

Detrital Nitrogen (mg N L-1) Phytoplankton 3 (mg Chl a L-1)

Data Sources

• Tributaries• Wastewater Treatment Facilities• Solar Radiation• Atmospheric Deposition• Kinetic Parameters• Benthic Fluxes (SOD and Nutrients)

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NBC Tributary Monitoring Stations

• Nutrient monitoring • 1 or 2 x per month• USGS flows adjusted to

account for ungauged flows

• Adjusted flows used to calculate loads

• Interpolate loads between monitoring dates

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Nutrient Loads from WWTFs

10Nixon et al. (1995)

Fields Point, Bucklin Point:• Monitored 3 X per week

Other 9 WWTFs:• Monthly data only

Nutrient Loads from WWTFs (cont.)

• Except for Bucklin and Fields Point Plants, loads calculated as product of monthly “average” concentrations and flows.

• Mass. plants had only 12-month running mean flows

• NH3 sometimes had to be estimated from TKN

• NO2 added to NO3

• Total P only monitored. DIP was estimated as 0.8 TP

• Si not monitored

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Seaward Boundary

12J. Krumholz (pers. comm.)

• Data for Krumholz Station #3 used for nutrients at seaward boundary

• Data are nominally monthly, but some months are missing

• Data are available only for the surface layer

Solar Radiation

13Solar Radiation at T.F. Green Airport

No locally measured solar radiation for Narragansett Bay for 2009, so used modeled data (National Solar Radiation Data Base) that has same statistical distribution as the local site.

Atmospheric Deposition and Kinetic Constants

Atmospheric deposition (NH3, NO3, ORGN, DIP, ORGP, CBOD) calculated using data from the literature(Nixon et al., 1995; Luo et al. ,2002; Bowen and Valiela, 2001; Yang et al., 1996; Nixon et al., 1995; Chen et al., 1985; Jurado et al., 2008)

Kinetic constants (typical values) from published studies and WASP documentation (Kremer and Nixon, 1978; Wang et al., 1999,(Ambrose and Wool, (undated)

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Sediment Oxygen Demand

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SOD based on Fulweiler and Nixon (2010)

Benthic Nutrient Fluxes

Data on nutrient flux rates, including temperature dependence, from a variety of sources: Lindsey Fields (pers. comm.) Fulweiler and Nixon (2010) Kremer and Nixon (1978)

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Simulation Results

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Dissolved oxygen

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Conimicut Pt.,near surface

Conimicut Pt.,bottom

Tributaries & effluentsall 8 layers

Total Nitrogen

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Conimicut Pt.

Gould I.

Tributaries & effluentsall 8 layers

Total Nitrogen (longitudinal gradient)

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Fields Pt. Bullock R.

Conimicut.

Warwick Pt. Hope I. N. J’town

Fields Pt.

.

Bullock R.

Conimicut.

Poppasquash Gould I.

East Passage, Fields Pt. Gould I.

West Passage,Fields pt. N. Jamestown

Tribs. & effluentsall 8 layers

Chlorophyll a

210

10

20

30

40

50

60

6/1/2009 6/21/2009 7/11/2009 7/31/2009 8/20/2009 9/9/2009 9/29/2009 10/19/2009

Ch

l a

(mg

/L)

Date

Comparing observed and simulated Chl a at Conimicut Pt. at noon(kwasp = 3, third layer from surface)

Simulated (Dosat)Observed

Mount View, near surface

Conimicut Pt., near surface

Tributaries & effluents top 2 layers

Summary/Discussion 1Simulation Results: At present, we’re simulating one phytoplankton group

Model does better at simulating seasonal patterns of DO and chl a than short-term dynamics

o This is likely caused, at least in part, by low frequency of boundary data, and surrogate solar radiation data

Simulation of seasonal chl a trends is getting close, but needs more work Simulation of seasonal DO trends (surface and bottom) is getting close, but needs more workSimulated longitudinal TN gradients look promising

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Summary/Discussion 2

Status of Database: Database for some variables is pretty good: e.g. DO, Chl a, salinity, temperature Database for in-estuary nutrients is sparse, especially below Providence River: surface only through 2010, less after that Only TP measured in WWTFs, silica essentially not at all Except for Narragansett Bay Commission Plants, data for nutrients are sketchy No solar radiation measurements on the Bay after 2008

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Where do we go from here?

Continue exploring effects of nonuniform vertical distribution of WWTF and tributary inputs

We’re improving treatment of benthic nutrient fluxesConsider phytoplankton metabolismContinue calibration of kinetic parameters

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Slides for possible discussion follow

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Periphyton Biomass

D : C : N : P : ChlIP

IN

Phytoplankton Biomass

Group 3D : C : N : P : Si: Chl DOGroup 2

D : C : N : P : Si: ChlGroup 1D : C : N : P : Si : Chl

TICH2CO3 – HCO3

- – CO32-

TotalAlkalinity

Particulate Detrital OM

SiPNCD

Dissolved OM

Si

P

N

CBOD1

CBOD2

CBOD3

Inorganic Nutrients

NO3PO4SiO2 NH4

pHpH

atmosphereatmosphere

uptakeexcretion

uptakeexcretion

Inorganic Solids

S3S1 S2

oxid

ation

oxid

ation

nitr

ifica

tion

photosynthesis and respiration

death

dissolution

mineralizationsorption

reaeration

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State Variables and Processes

DON and DIN in Narragansett BayBaywide and segment-specific mean DON and DIN concentrations and DON/DIN ratios in Narragansett Bay in SINBADD Cruises (1985-1986)*.

*Pilson, M.E.Q. and C.D. Hunt. 1989. Water quality survey of Narragansett Bay: A summary of results from the SINBADD 1985-1986. Marine Ecosystems Research Laboratory. GSO, URI: 124 pp. Available as Report NBEP-89-22 at http://www.nbep.org/publications.html. 27

SINBADD cruise Baywide

DON (mm)Baywide

DIN (mm)Baywide DON/DIN

Range among segments: DON/DIN

October 1985 16.4 7.6 2.2 0.46 - 7.26November 1985 13.6 13.5 1.0 0.27 - 2.35April 1986 10.5 1.0 10.5 1.70 - 26.0May 1986 14.0 1.7 8.2 0.95 - 29.7

DON usage by Bacteria & Flagellates

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Fraction of DON used by bacteria & heterotrophic flagellates over 8-15 days, by source and season (Seitzinger and Sanders 1997)*.

*Seitzinger, S.P. and R.W. Sanders. Contribution of dissolved organic nitrogen from rivers to estuarine eutrophication. Marine Ecology Progress Series 159: 1-12.

DON source and month Fraction DON used (%)

Length of incubation (days)

Delaware River (April) 72 15Delaware River (June) 40 8Hudson River (June) 40 10

Fraction of DON Used by Bacteria and Phytoplankton

Fraction of DON used over 10 – 12 days, by source (Seitzinger et al. 2002)*.

*Seitzinger, S.P., R.W. Sanders, and R. Styles, Bioavailability of DON from natural and anthropogenic sources to estuarine plankton. Limnology and Oceanography 47(2):353-366.

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Runoff source Percent DON used (mean ± SD)

Urban/suburban 59 ± 11Agricultural pastures 30 ± 14Coniferous and hardwood forests 23 ± 19