lower cape fear river estuary model progress report jim bowen, unc charlotte october 11, 2007...
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Lower Cape Fear River EstuaryModel Progress Report
Jim Bowen, UNC Charlotte
October 11, 2007
Charlotte, NC (via Centra)
Description of Model Application
Open BoundaryElevation Cond.
Lower Cape Fear RiverEstuary Schematic
Black River, FlowBoundary Cond.
Cape Fear R. Flow Boundary Cond.
NE Cape FearFlow Boundary Cond.
DO Conceptual ModelBOD Sources
Sediment Sediment O2 Demand
Cape Fear BOD Load
NECF & Black R. BOD Load
Muni & Ind. BOD Load
decaying phytopl.
DO Conceptual ModelBOD Sources, DO Sources
Sediment Sediment O2 Demand
Ocean Inflows
SurfaceReaeration
Phytoplank. Productivity
MCFR Inflows
BOD Consumption
DO Conceptual ModelBOD Sources, DO Sources & Sinks
Sediment Sediment O2 Demand
Ocean Inflows
SurfaceReaeration
Input of NECF & Black R. Low DO Water
BOD Consumption
DO Conceptual ModelBOD Sources, DO Sources & Sinks
Sediment Sediment O2 Demand
Cape Fear BOD Load
NECF & Black R. BOD Load
Ocean Inflows
SurfaceReaeration
Input of NECF & Black R. Low DO Water
Phytoplank. ProductivityMuni & Ind.
BOD Load
decaying phytopl.
MCFR Inflows
Modeling Developments
1. Finished Defining Model Grid• Bottom roughness investigation
• Finished sizing marsh cells
2. Further Developed Salinity Boundary Condition at Estuary Mouth
3. Finished Hydrodynamic Model Calibration
4. WQ Predictions Using New Grid
Hydrodynamic Calibration - Summary, 8/07
• Excellent agreement w/ temperature and salinity
• Elevation agreement (not shown) still needs some work to get predicted tidal amplitude attenuation to match observed attenuation
Model Grid Definition, Procedure
• Objective was to match tidal amplitudes at USGS Stations– Upper Estuary ( Lock and Dam 1, Black at
Currie, NECF at Burgaw)– Middle Estuary (Navassa, NECF at
Wilmington)– Lower Estuary (Marker 12)
Sizing Marsh Cells, Procedure
• Systematically varied grid parameters to match observed elevation data– Rougher bottoms damp tidal amplitudes– More off-channel storage in wetland cells
damps tidal amplitudes
Step 1. Can changes in channel roughness produce desired amplitude attenuation?• Used existing model grid
Existing Model Grid• w/ changes described
in August update• 1004 water cells• Has “marsh cells” in
Black and NECF• Marsh cells 2.0 m
deep• All cells have the
same roughness• See kmz file for
more detail
Step 1. Can changes in channel roughness produce desired amplitude attenuation?• Used existing model grid
• Varied roughness across grid – Typical value = 0.02– Minimum = 0.015 m (very smooth)– Maximum = 0.045 m (very rough)
• Looked at changes in amplitude as bottom roughness increased
Results, Variable Bottom Roughness
M2 Tidal Amplitudes, LCFR
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
1 2 3 4 5 6 7
Amplitude (m)
n=0.015
n=0.025
n=0.035
n=0.045
observed
Upper Estuary Middle Estuary Lower EstuaryL&D#1, Currie, Burgaw Navassa, Wilmington M12, M18
Results, Variable Bottom Roughness
M2 Tidal Amplitudes, LCFR
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
1 2 3 4 5 6 7
Amplitude (m)
n=0.015
n=0.025
n=0.035
n=0.045
observed
Upper Estuary Middle Estuary Lower EstuaryL&D#1, Currie, Burgaw Navassa, Wilmington M12, M18
Upper Estuary
Stations Underdamped
Results, Variable Bottom Roughness
M2 Tidal Amplitudes, LCFR
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
1 2 3 4 5 6 7
Amplitude (m)
n=0.015
n=0.025
n=0.035
n=0.045
observed
Upper Estuary Middle Estuary Lower EstuaryL&D#1, Currie, Burgaw Navassa, Wilmington M12, M18
Middle Estuary
Stations Underdamped
Results, Variable Bottom Roughness
M2 Tidal Amplitudes, LCFR
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
1 2 3 4 5 6 7
Amplitude (m)
n=0.015
n=0.025
n=0.035
n=0.045
observed
Upper Estuary Middle Estuary Lower EstuaryL&D#1, Currie, Burgaw Navassa, Wilmington M12, M18
Very little sensitivity to bottom roughness
Sizing Off-Channel Storage, Procedure
1. Went through model grid and resized “marsh cells” to roughly fit wetland delineations
2. Developed a method to quickly vary width and roughness of marsh cells, create EFDC grid files, and see results w/ Google Earth
3. Ran model many times w/ various marsh configurations and observed results
First step, try various marsh cell widths• Varied marsh cell widths
– Base case– Base case * 2– Base case * 5– Base case * 10
• Determined how width changes affected tidal amplitudes
Base Case
Base Case, Width x 2
Base Case, Width x 5
Base Case, Width x 10
Results, Marsh Width VariationM2 Amplitudes at Seven Locations
0.000
0.100
0.200
0.300
0.400
0.500
0.600
0.700
0.800
0.900
1 2 3 4 5 6 7
M2 Amplitude (m)
base
width *2
width * 5
width * 10
observed
Lock andDam 1
Black at Currie
NECF atBurgaw
CF at Navassa
NortheastCF @ Wilm.
Marker12
CF at mouth
Results, Marsh Width VariationM2 Amplitudes at Seven Locations
0.000
0.100
0.200
0.300
0.400
0.500
0.600
0.700
0.800
0.900
1 2 3 4 5 6 7
M2 Amplitude (m)
base
width *2
width * 5
width * 10
observed
Lock andDam 1
Black at Currie
NECF atBurgaw
CF at Navassa
NortheastCF @ Wilm.
Marker12
CF at mouth
• Width ratio = 2.0 gives best results overall
• Need additional damping at Navassa
• Added additional marsh cells in middle estuary (V1, V2)
• Also tried smaller changes in marsh width (1.5, 2.0)
Version 1, Width x 2
Version 2, Width x 1.0/2.0
Version 3, Width x 1.5
Results, Tidal AmplitudesM2 Amplitudes at Seven Locations
0.000
0.100
0.200
0.300
0.400
0.500
0.600
0.700
0.800
0.900
1 2 3 4 5 6 7
M2 Amplitude (m)
width *2
width *2, v1
v2, width = 1.0/2.0
v3, width * 1.5
observed
Lock andDam 1
Black at Currie
NECF atBurgaw
CF at Navassa
NortheastCF @ Wilm.
Marker12
CF at mouth
Results, Tidal AmplitudesM2 Amplitudes at Seven Locations
0.000
0.100
0.200
0.300
0.400
0.500
0.600
0.700
0.800
0.900
1 2 3 4 5 6 7
M2 Amplitude (m)
width *2
width *2, v1
v2, width = 1.0/2.0
v3, width * 1.5
observed
Lock andDam 1
Black at Currie
NECF atBurgaw
CF at Navassa
NortheastCF @ Wilm.
Marker12
CF at mouth
• Unable to match exactly the observed pattern in amplitude reduction
• V2, Width ratio = 2.0 (in green) determined to give the best results overall
Version 1, Width x 2
Previous Model Grid
New Grid Characteristics
• Off-channel storage locations based on wetland delineations
• 46 additional marsh cells added (1050 total cells)
• Additional off-channel storage added to each basin (Cape Fear, Black, NECF)
• Significant amount of marsh area added to middle and lower estuary
Results for New Grid
• Also investigated alternate boundary condition specification– Now use AM and PM max salinity at station
M12 rather than daily max
• Now use hourly rather than 12-hour averaged monitoring data
• Looked at observed vs. predicted temperatures, salinities, elevations
• Compared results to those obtained previously w/ previous model grid
Elevations, Currie, June 04
Elevations, Burgaw, June 04
Elevations, Navassa, June 04
Elevations, NECF Wilm., June 04
Elevations, Mrkr 12, June 04
April - November 2004 Temp., 8/07
April - November 2004 Temp., New
April - November 2004 Temp., 8/07
Statistical Measures of Fit (units of deg C)
mean(pred-obs) =0.10046 ME_norm =0.0043473 RMSE =0.96224 MAE =0.71269 MAE_norm =0.030841 RMSE_norm =0.041639 r_squared =0.97272 num data comparisons = 4150 r2 adjusted for bias = 0.96465
April - November 2004 Temp., New
Statistical Measures of Fit (units of deg C)
mean(pred-obs) =0.034678 ME_norm =0.0015146 RMSE =0.95803 MAE =0.71946 MAE_norm =0.031423 RMSE_norm =0.041843 r_squared =0.97439 num data comparisons = 4579 1-mse/var(obs) = 0.96604
April - November 2004 Salinity, 8/07
April - November 2004 Salinity, New
April - November 2004 Salinity, 8/07
April - November 2004 Salinity, New
April - November 2004 Salinity, 8/07
April - November 2004 Salinity, New
April - November 2004 Salinity, 8/07
April - November 2004 Salinity, New
April - November 2004 Salinity, 8/07
Statistical Measures of Fit (units of PSU)
mean(pred-obs) =-0.25797 ME_norm =-0.043321 RMSE =2.6493 MAE =1.6424 MAE_norm =0.27581 RMSE_norm =0.4449 r_squared =0.87049 num data comparisons = 3517 1-mse/var(obs) = 0.84804
April - November 2004 Salinity, 8/07
Statistical Measures of Fit (units of PSU)
mean(pred-obs) =-0.0044639 ME_norm =-0.00083995 RMSE =2.64 MAE =1.5505 MAE_norm =0.29176 RMSE_norm =0.49675 r_squared =0.87044 num data comparisons = 3953 1-mse/var(obs) = 0.85345
Summary of Progress
• Model grid now includes a significant amount of off-channel storage
• Salinity mean errors now very low (important for predicting dilution)
• Tidal elevation attenuation now well simulated
• Hydrodynamic & conservative transport submodels now calibrated
Summary of Progress, cont’d
• Also have developed a program for animating horizontal contour in Google Earth (good for showing DO results)
• Benoit Duclaud finished Masters thesis on new method for predicting reaeration (thesis, paper available next month)
Information Available Online
• See LCFR website for more infowww.coe.uncc.edu/~jdbowen/LCFR
• This presentation is available
• Google Earth files available for download– Grid and wetland data from presentation– Monitoring stations, point sources– Final EFDC grid information– NOAA bathymetry
Present Work
• Running water quality model now w/ new grid• Still waiting to get BOD data from LCFR Program• Finish assigning decay rates and redefining loads
once additional BOD data are available• Work on incorporating SOD data in a more
detailed way• Do additional model/data comparisons w/ DWQ
special study data