Patapsco/Back River SWMM Model
Part II – SWMM Water Quality Calibration
Maryland Department of the Environment
Water Quality Calibration
General– Aggregate Five Subwatersheds– Focus on predominant land uses – Calibrate EOS loads to literature values– Calibrate Event Mean Concentrations
Detailed– Time series overlay– Comparative Analysis
Water Quality CalibrationUrban TSS and Metals Objective
– EMC (statistics of wet-weather events)– Unit Load (annual)
Parameters– Buildup Rate (Linear - Calibrated)– Build Limit (Set high)– Wash-off Coefficient (Based on Literature)– Wash-off Exponent (Based on Literature)
Calculation– Load = (Flow*Conc.) – EMC = Load / Flow
Results– Unique Solution of Buildup Rate
Validation– Timeseries Comparision
Water Quality Calibration Non-Urban Land Use (USLE) Calibration Objective
– Correlate with long term loading rate estimates USLE – Estimates gross long term erosion rate
– Parameters (Land use specific)R=Rainfall Energy (from BWI)K=Soil Erodibility (Soil type)LS=Slope Length Gradient Ratio (DEM)C=Cropping Management Factor (Landuse – Calibrated)P=Erosion Control Practice (Literature)
Delivery Ratio– Applied Based on Subwatershed Drainage to Baltimore Harbor
Parameter– Adjusted cropping management factor within recommended values
Literature Data Source CI HDR MDR LDR Water Open CL PL FL Barren
Baltimore City NPDES Report (1998) X X X
Baltimore City NPDES Report (1999) X X X
Baltimore City NPDES Report (2000) X X X
Harford County NPDES Report (1999) X X X
Harford County NPDES Report (2000) X X X
Frederick County NPDES Report (1999-2000) X
Howard County NPDES Report (1999) X X X
NPDES Monitoring (1992-1995) X X X X
NPDES Monitoring (1995-2000) X X X X
NURP Residential X X X
Urbonas and Stahre (1993) X
Howard County (1998) - Font Hill Tributary X X X
Baltimore County Storm Water Monitoring Data (CDM, 1996) X X X X
Baltimore County NPDES Monitoring (1990-1995) X X X X X X
Baltimore County NPDES Report (1998) X X X X
Baltimore County NPDES Report (1999) X X X X
Baltimore County NPDES Report (2000) X X X X
Event Mean Concentration References
Unit Load ReferencesLiterature Data Source CI HDR MDR LDR Water Open CL PL FL Barren
Baltimore City NPDES Report (1997) X
Baltimore City NPDES Report (1998) X
Baltimore City NPDES Report (1999) X
Harford County NPDES Report (1999) X
Harford County NPDES Report (2000) X
Baltimore County NPDES Report (2000) X X X X X X X X X
Jones Falls Water Quality Management Plan (1997) X X X X X X X X X X
Loch Raven Water Qulity Management Plan (1997) X X X X X X
Loch Raven Water Qulity Management Plan (1997) - model X X X X X X X X X
Corsi et al., 1997 X X
Horner et al., 1994 X X
Smith et al., 1991 X X X
CBP Patapsco/Back River (1984-1994) X X X
CBP Patapsco/Back River (1984-1997) X X X
CBP Patapsco/Back River (1993-1997) X X X
Maryland NPDES Monitoring Report (1997) X X X X
Watershed Station ID Station Location Constituent Sampling Period # Samples
Jones Falls 240 Sorrento USGS Gauge TSS 1/9/97 - 12/23/97 65
Jones Falls 241 Downstream TSS 1/9/97 - 12/23/97 59
Jones Falls 241 Donwstream Pb/Zn 6/17/97 - 6/12/98 62
Gwynns Falls 230 Villa Nova USGS Gauge TSS 1/9/97 - 12/23/97 58
Gwynns Falls 231 Downstream TSS 1/9/97 - 12/23/97 70
Gwynns Falls 231 Downstream Pb/Zn 6/17/97 - 6/12/98 78
Patapsco River 211 Hollofield USGS Gauge Pb/Zn 6/17/97 - 6/12/98 61
Back River 250 Herring Run USGS Gauge TSS 1/9/97 - 12/23/97 55
Back River (Moores Run) - Radecke Ave. Pb/Zn 2/28/95 - 1/09/01 809
Back River (Moores Run) - Radecke Ave. TSS 2/28/95 - 1/09/01 1231
Back River (Moores Run) - Biddle St. & 62nd St. Cr/Pb/Zn 6/10/97 - 8/15/00 41
Back River (Chinquapin Run) - Hillen Road Cr/Pb/Zn 6/9/97 - 8/15/00 37
Back River (Herring Run) - Pulaski Highway Cr/Pb/Zn 5/14/97 - 8/15/00 40
Water Quality Data
-DNR Core station TSS data available at stations 240, 230 and 211 (Data set contains mostly base flow samples)- Metals values not shown from 2/25/95 to 12/1/96 due to high detection limits
*All data collected by Baltimore City
SWMM Baseflow Concentration
Base Flow Data Source TSS Cr Zn Pb
Baltimore County NPDES Report (2000) X
Baltimore City NPDES Report (2001) X
Baltimore City Wastewater Facilities Master Plan (1997) X X X
Baltimore County DEPRM Watershed Monitoring Project (1997-2000) X
MDE Upper Western Shore Monitoring Project (2001) X
Constituent Gwynns Falls Jones Falls Patapsco River Baltimore Harbor Back River
TSS (mg/L) 4.17 5.15 6.19 4.66 3.06
Cr (mg/L) 0.00075 0.00062 0.00081 0.00069 0.00048
Zn (mg/L) 0.0184 0.0229 0.0154 0.02065 0.0286
Pb (mg/L) 0.0017 0.0017 0.0017 0.0017 0.0017
References
Concentrations
Results
TSS
1
10
100
1000
10000
CI HDR MDR LDR WATER OPEN CL PAST FOR BAR
TS
S E
MC
(m
g/L
)
SWMM Model (avg)Literature (avg)MD 1992-1995MD 1995-2000Avg. baseflow conc/load
0
200
400
600
800
1000
1200
CI HDR MDR LDR WATER OPEN CL PAST FOR BAR
TS
S L
oad
(lb
/ac/
yr)
Cr
0.00000
0.00100
0.00200
0.00300
0.00400
0.00500
0.00600
0.00700
0.00800
0.00900
0.01000
CI HDR MDR LDR WATER OPEN CL PAST FOR BAR
Cr
EMC
(m
g/L
)
SWMM Model (avg)Literature (avg)MD 1992-1995MD 1995-2000Avg. baseflow conc/load
0.00000
0.01000
0.02000
0.03000
0.04000
0.05000
0.06000
CI HDR MDR LDR WATER OPEN CL PAST FOR BAR
Cr
Lo
ad (
lb/a
c/yr
)
Zn
0.00000
0.05000
0.10000
0.15000
0.20000
0.25000
CI HDR MDR LDR WATER OPEN CL PAST FOR BAR
Zn
EM
C (
mg
/L)
SWMM Model (avg)Literature (avg)MD 1992-1995MD 1995-2000Avg. baseflow conc/load
0.00000
0.20000
0.40000
0.60000
0.80000
1.00000
1.20000
1.40000
1.60000
1.80000
CI HDR MDR LDR WATER OPEN CL PAST FOR BAR
Zn
Lo
ad (
lb/a
c/yr
)
Pb
0.00000
0.01000
0.02000
0.03000
0.04000
0.05000
0.06000
0.07000
0.08000
CI HDR MDR LDR WATER OPEN CL PAST FOR BAR
Pb
EM
C (
mg
/L)
SWMM Model (avg)Literature (avg)MD 1992-1995MD 1995-2000Avg. baseflow conc/load
0.00000
0.05000
0.10000
0.15000
0.20000
0.25000
CI HDR MDR LDR WATER OPEN CL PAST FOR BAR
Pb
Lo
ad (
lb/a
c/yr
)
Jones Falls
Jones Falls at Maryland Ave.Daily Flow
0
200
400
600
800
1000
1200
Jun-
97
Jul-9
7
Aug
-97
Sep
-97
Oct
-97
Nov
-97
Dec
-97
Jan-
98
Feb
-98
Mar
-98
Apr
-98
Time
Flo
w (
cfs)
Pb Concentration Time Series Jones Falls (downstream)
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
0.18
Jun-
97
Au
g-9
7
Se
p-9
7
No
v-97
De
c-97
Fe
b-9
8
Ap
r-9
8
Ma
y-98
Pb
(m
g/L
)
Pb - BC Station 241
Pb - SWMM
Zn Concentration Time Series Jones Falls (downstream)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
Jun-
97
Aug
-97
Sep
-97
Nov
-97
Dec
-97
Feb
-98
Apr
-98
May
-98
Zn
(m
g/L
)
Zn - BC Station 241
Zn - SWMM
Patapsco
Patapsco River at HollofieldDaily Flow
0
200
400
600
800
1000
1200
1400
1600
1800
2000
Jun-
97
Jul-9
7
Aug
-97
Sep
-97
Oct
-97
Nov
-97
Dec
-97
Jan-
98
Feb
-98
Mar
-98
Apr
-98
Time
Flo
w (
cfs)
SWMM
Pb Concentration Time Series Patapsco River (Hollofield Gauge)
0
0.02
0.04
0.06
0.08
0.1
0.12
Jun-
97
Au
g-9
7
Se
p-9
7
No
v-97
De
c-97
Fe
b-9
8
Ap
r-9
8
Ma
y-98
Pb
(m
g/L
)
Pb - BC Station 211
Pb - SWMM
Zn Concentration Time Series Patapsco River (Hollofield Gauge)
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
Jun-
97
Aug
-97
Sep
-97
Nov
-97
Dec
-97
Feb
-98
Apr
-98
May
-98
Zn
(m
g/L
)
Zn - BC Station 211
Zn - SWMM
Back River
Back River (Moores Run Gauge - Radecke Ave.)Daily Flow
0
50
100
150
200
250
300
350
400
De
c-9
6
Ma
r-9
7
Jun
-97
Se
p-9
7
De
c-9
7
Ma
r-9
8
Jun
-98
Se
p-9
8
De
c-9
8
Ma
r-9
9
Jun
-99
Se
p-9
9
De
c-9
9
Ma
r-0
0
Jun
-00
Se
p-0
0
De
c-0
0
TimeF
low
(c
fs)
Pb Concentration Time Series Back River (Moores Run - Radecke Ave)
0
0.05
0.1
0.15
0.2
0.25
0.3
De
c-96
Jun-
97
Jan-
98
Jul-9
8
Fe
b-9
9
Au
g-9
9
Ma
r-0
0
Oct
-00
Pb
(m
g/L
)
Pb - BC/Radecke
Pb - SWMM
Zn Concentration Time Series Back River (Moores Run - Radecke Ave)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
Jul-9
5
Jan-
96
Aug
-96
Feb
-97
Sep
-97
Mar
-98
Oct
-98
May
-99
Nov
-99
Jun-
00
Dec
-00
Zn
(m
g/L
)
Zn - BC/Radecke
Zn - SWMM
Best Management Practices (BMPs)
Uncertainty and variability in EMC– Instream sites from NPDES Report
Timeseries comparison of model vs data show reasonable concentration magnitude agreement
BMPs not explicitly included in model Established a baseline load scenario
Sub-Watershed LoadsAverage Annual Total Load (1992 -2000)
Sub-WateshedFlow
(MG/yr)TSS
(ton/yr)Cr
(lb/yr)Zn
(lb/yr)Pb
(lb/yr)
Baltimore Harbor 41,130 6,415 1,132 31,623 5,128
Gwynns Falls 24,851 4,495 529 15,797 2,826
Jones Falls 21,549 4,971 348 12,003 2,038
Patapsco River 71,335 25,205 961 25,963 4,841
Total 158,865 41,086 2,970 85,385 14,834
Average Annual Baseflow Load (1992 -2000)
Sub-WatershedCr
(lb/yr)Zn
(lb/yr)Pb
(lb/yr)
Baltimore Harbor 85 2,535 211
Gwynns Falls 68 884 144
Jones Falls 56 1,650 139
Patapsco River 320 4,753 671
Total 529 9,822 1,165
% Base Load 17.8% 11.5% 7.9%
Landuse
CI12%
HDR8%
MDR19%
LDR11%
CL12%
PAST3%
FOR28%
BAR1%
OPEN4%
WATER2%
Baltimore Harbor Watershed Land Use Loading Summary
CBP TSS Results (93-97)
Urban: 44.5%Crop: 28.4%Pasture: 4.1%Forest: 23.1%
Land Use TSS (tons/yr) Cr (lb/yr) Zn (lb/yr) Pb (lb/yr)
CI 6,462 1,793 41,173 6,258
HDR 3,056 212 11,131 2,207
MDR 4,687 393 15,365 2,747
LDR 2,307 225 7,731 1,135
WATER 40 3 125 78
OPEN 839 25 1,238 340
CL 15,737 89 2,861 552
PAST 2,845 26 816 155
FOR 4,941 200 4,830 1,333
BAR 172 4 116 29
Sum 41,086 2,970 85,385 14,834
Land Use TSS (tons/yr) Cr (lb/yr) Zn (lb/yr) Pb (lb/yr)
CI 16% 60% 48% 42%
HDR 7% 7% 13% 15%
MDR 11% 13% 18% 19%
LDR 6% 8% 9% 8%
Sum Urban 40% 88% 88% 83%
WATER 0% 0% 0% 1%
OPEN 2% 1% 1% 2%
CL 38% 3% 3% 4%
PAST 7% 1% 1% 1%
FOR 12% 7% 6% 9%
BAR 0% 0% 0% 0%
Watershed SourceArea (acre)
TSS (tons)
Zn (lbs)
Pb (lbs)
Back River MDE SWMM (1992 - 2000) 35,623 3,531 15,907 2,577
MDE HSPF (1993 - 1997) -2.4% -40%
Back River Watershed Water Quality Management Plan (Baltimore County, 1996)
-10% -30% 32%
CBP Version 4.3 (1993 - 1997) 31.5% 107%
Back River MDE SWMM (1999) 2273 241 979 166
(Moores Run at Radecke Ave.) Moores Run Watershed Plan (Baltimore City, 2001) 2.2% -1% 1% 12%
Back River MDE SWMM (1999) 3194 357 1536 261
(Moores Run Watershed) Moores Run Watershed Plan (Baltimore City, 2001) -5.2% 26% 21% 40%
Baltimore Harbor MDE SWMM (1992 - 2000) 271,162 41,086 85,385 14,834
MDE HSPF (1993 - 1997) -1.6% -40%
CBP Version 4.3 (1993 - 1997) -5.6% 118%
Upper Jones Falls MDE SWMM (1992 - 2000) 16,946 2570 3341 535
Jones Falls Watershed Water Quality Management Plan (Baltimore County, 1997) Sub-watersheds 1,2,3,4 & 8 year 1982
0.0% -57% -55% 19%
Lake Roland Project (Observed) (Urban Clean Lakes Initiative,1984)
-8.1% 703%
Lake Roland Project (NVDPC) (Urban Clean Lakes Initiative,1984)
-8.1% 71%
Baltimore Harbor MDE SWMM (1992-2000) 9,684 707 3946 638
(Bear Creek & Old Road Bay)Baltimore Harbor Watershed Water Quality Management Plan (Baltimore, County, 2000)
0.8% -31% 8% 181%
Jones Falls MDE SWMM (1992 - 2000) 6992 863
(Roland, Towson and Cochran Run)Lake Roland Project (Observed) (Urban Clean Lakes Initiative,1984)
-18.1% -22%
Lake Roland Project (NVDPC) (Urban Clean Lakes Initiative,1984)
-18.1% 21%
Comparative Analysis - Existing Studies
SWMM Calibration Summary & Conclusions
Focus on predominant land use for model calibration Calibrate EOS loads to mean literature values Calibration urban EMC’s to reported mean landuse
values Overlay model with water quality timeseries data Comparative Analysis Model supports overall trends (Flow, TSS and
metals) Next - Sensitivity of water quality model to NPS
Loads
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