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Modeling Sediment and Nutrient Loads Input to
Great Lakes and Effects of Agricultural
Conservation Practices on Water Quality
C. Santhi and CEAP National Assessment Team
Texas A&M University System, Temple, Texas
• CEAP National Assessment
- CEAP/SWAT/APEX Modeling Approach
• Great Lakes Basin – Calibration and Validation
• Determine the Sediment and Nutrient Load Input to each
of the Great Lakes
• Determine the Major Sources of Sediment and Nutrients
discharged to local waters in Great Lake Basin
• Determine the Off-site Benefits of Agricultural
Conservation Practice Scenarios on Water Quality in each
of the Great Lakes
Presentation Overview
3
Conservation Effects Assessment
Project (CEAP) - National Assessment
To measure the environmental benefits of conservation
programs currently on cropland
at regional/national level, and
To assess the potential environmental benefits of additional
conservation treatment needs to meet the nation’s natural
resources
CEAP – Cropland National Assessment : Goal
Conservation programs/practices implemented in the US since
1960’s and earlier to increase agricultural production, control soil
erosion and nutrient losses and sustain the environment
Cultivated Cropland &CRP: Edge of field flow, sediment, nutrient & pesticide loadings from subareas with practices
Uncultivated Land: Flow, sediment, nutrient and pesticide loadings from HRUs
1. Current Conservation Baseline: SWAT simulation using APEX output with current conservation practices 2. No Practice: SWAT simulation using APEX output without conservation practices3. Additional Treatment Need: SWAT simulation using APEX output with ENMC and ENMA4. Background: SWAT simulation using APEX output with background grass-tree mix condition
1. Reductions in sediment, nutrients and pesticide yields and loads at 8-digit watersheds due to current conservation practices and additional treatment practices on cropland2. Reductions in instream loads at river points due to current conservation and additional treatment scenarios
Instream Processes: Routing through reach, ponds, reservoirs to 8-digit watershed outlet & through main river reaches to basin outlet
NRI/Survey/Conservation Practice Details- Structural Practices- Cultural Management Practices- Practice Acres- Farming Activities/Survey Database- NRI
Watershed Configuration Details(Subbasins/Rivers/Routing/Reservoirs)
Weather (Precipitation, Temperature and others)
Dry and Wet Atmospheric Nitrogen Deposition
INTEGRATE APEX OUTPUT
SCENARIOS
(Calibrated)(Calibrated)
RESULTS
Conservation Scenarios1. Current Conservation Baseline: APEX inputs with current conservation practices from CEAP survey 2. No Practice: APEX inputs without conservation practices3. Additional Treatment Need: APEX inputs with different combinations of practices & practice acres (ENMC and ENMA)4. Background: APEX inputs with grass-tree mix condition on cropland
Effects on Edge of Field Water Quality
Effects on Local/Instream Water Quality
Point Sources: Flow, TSS and nutrient loadings from Municipal and IndustrialPlants
CEAP/SWAT/APEX National Modeling System
Landuse, Soils and Management Practices
5
Largest surface freshwater system
in the world (21%). 84% of US
Water Supply.
Population: 30 Million
Drainage Area: 521, 830 km2 (US and Canada) (451,545 km2)
7% - U.S. Farm Production
25% - Canadian Ag. Production
Dominant source of sediment and nutrients to the Lakes
Eutrophication–Low DO-Fish Kill
Lake Erie: P enrichment; Algal bloom
Great Lakes Basin
Cropland %
Figure. 1. Great Lakes Basin with gages and cropland area distribution
Calibration and Validation Gages
Gauging Station Name Gage ID
on Map
Hydrologic
Unit Code
Lake Drainage
Area (km2)
Calibration Gages
St Louis River at Scanlon, MN S1 04010201 Superior 8,884
Fox river at Appleton, WI S2 04030204 Michigan 15,411
Grand River at Grand Rapids, MI S3 04030204 Michigan 12,691
Saginaw River at Saginaw, MI S4 04080206 Huron 15,695
Maumee River at Waterville, OH S5 04100009 Erie 16,395
Sandusky River near Fremont OH S6 04100011 Erie 3,240
Oswego River at Oswego, NY S7 04140203 Ontario 13,209
Validation Gages
Ontonagon River near Rockland, MI S8 04020102 Superior 3,471
St. Joseph River at St. Joseph, MI S9 04050001 Michigan 12,095
Grand River at Eastmanville, MI S10 04050006 Michigan 13,701
River Raisin near Monroe, MI S11 04100002 Erie 2,699
Cuyahoga River Independence, OH S12 04110002 Erie 1,831
Grand River near Painesville OH S13 04110004 Erie 1,774
a) Streamflow Calibration
y = 1.05x
R2 = 0.91
0
50
100
150
200
250
0 50 100 150 200 250
Observed Flow m3/s
Sim
ula
ted
Flo
w m
3/s
b) Sediment Calibration
y = 0.902x
R2 = 0.998
0
500
1000
1500
2000
0 500 1000 1500 2000
Observed Load (1000 Tonnes)
Pre
dic
ted
Lo
ad
(1000 T
on
nes)c) Total Nitrogen Calibration
y = 0.993x
R2 = 0.872
0
15000
30000
45000
60000
0 15000 30000 45000 60000
Observed Load (Tonnes)
Pre
dic
ted
Lo
ad
(T
on
nes)
d) Total Phosphorus Calibration
y = 1.007x
R2 = 0.853
0
1000
2000
3000
0 1000 2000 3000
Observed Load (Tonnes)
Pre
dic
ted
Lo
ad
(T
on
nes)
a) Annual Flow at Waterville, OH on the Maumee River
0
200
400
600
800
1000
19
61
19
63
19
65
19
67
19
69
19
71
19
73
19
75
19
77
19
79
19
81
19
83
19
85
19
87
19
89
19
91
19
93
19
95
19
97
19
99
20
01
20
03
20
05
Flo
w (
mm
)
Observed Predicted
b) Sediment Load at Waterville, OH on the Maumee River
0
2
4
6
8
19
61
19
63
19
65
19
67
19
69
19
71
19
73
19
75
19
77
19
79
19
81
19
83
19
85
19
87
19
89
19
91
19
93
19
95
19
97
19
99
20
01
20
03
20
05
Lo
ad
(M
illio
n T
on
ne
s)
Observed Predicted
c) Total Nitrogen Load at Waterville, OH on the Maumee River
0
30
60
90
120
19
74
19
76
19
78
19
80
19
82
19
84
19
86
19
88
19
90
19
92
19
94
19
96
19
98
20
00
20
02
20
04
Year
Lo
ad
(1
00
0 T
on
ne
s)
Observed Predicted
d) Total Phosphorus Load at Waterville, OH on the Maumee River
0
2,000
4,000
6,000
8,000
19
74
19
76
19
78
19
80
19
82
19
84
19
86
19
88
19
90
19
92
19
94
19
96
19
98
20
00
20
02
20
04
Lo
ad
(T
on
ne
s)
Observed Predicted
Calibration Results at the Gages
a) Streamflow Validation
y = 1.03x
R2 = 0.99
0
50
100
150
200
0 50 100 150 200
Observed Flow m3/s
Pre
dic
ted
Flo
w m
3/s
b) Sediment Validation
y = 1.6069x
R2 = 0.8422
0
50000
100000
150000
200000
250000
0
50000
100000
150000
200000
250000
Observed Sediment (Tonnes)
SW
AT
Sed
imen
t (T
on
nes)
c) Total Nitrogen Validation
y = 1.5674x
R2 = 0.95
0
5000
10000
15000
20000
25000
0 5000 10000 15000 20000 25000
Flux MasterTN (Tonnes)
SW
AT
TN
(T
on
nes)
d) Total Phosphorus Validation
y = 1.2766x
R2 = 0.7162
0
200
400
600
800
0 200 400 600 800
Flux Master TP (Tonnes)
SW
AT
TP
(T
on
nes)
Validation Results at the Gages
1) Estimate the sediment and nutrient loads delivered to
discharged to each Great Lake,
2) Determine the major sources of sediment and
nutrients delivered to local waters in each Great
Lakes Basin, and
3) Evaluate the effects of current agricultural
conservation practices and future conservation needs
on water quality in the Great Lakes Basin
Specific Objectives
11
Loads Discharged to Great Lakes: Prediction and Validation
a) Total Nitrogen Discharges to the Great Lakes
y = 1.04x
R2 = 0.63
0
25,000
50,000
75,000
100,000
125,000
150,000
0
25,0
00
50,0
00
75,0
00
100,0
00
125,0
00
150,0
00
SPARROW Total N (Tonnes/Yr)
SW
AT
To
tal N
(T
on
nes/Y
r)
b) Total Phosphorus Discharges to the Great Lakes
y = 1.39x
R2 = 0.93
0
2,000
4,000
6,000
8,000
0 2,000 4,000 6,000 8,000
SPARROW Total P (Tonnes/Yr)
SW
AT
To
tal P
(T
on
nes/Y
r)
(without wind, gully and
bank erosion)
Sediment and Nutrient Loads Delivered to Great Lakes (CEAP)
658,3512,469,382 1,126,735
3,528,0781,340,833
9,506
116,59949,252
113,37941,324
563
4,0141,522
6,721 3,290
110
1001,000
10,000100,000
1,000,00010,000,000
Lake Superior Lake
Michigan
Lake Huron Lake Erie Lake Ontario
Load
s (T
on
nes
)
Sediment Nitrogen Phosphorus
c) Phosphorus
Cultivated Cropland
Grassland
Urban (Non-point)
Forest and Others
Point Sources
Sources of Sediment and Nutrients
13
Practices Simulated Within APEX
In-field Practices for Erosion Control
• Contour Farming
• Strip Cropping
• Contour Buffer Strips
• Terraces
• Grass Terraces
• Tile Drain
• Grade Stabilization Structures
• Grassed Waterways
• Diversion
Edge of Field Practices for buffering• Filter Strips • Riparian Forest Buffers• Riparian Herb. Cover• Field Borders• Vegetative Barrier Wind Erosion Control
Practices• Windbreak / Shelterbelt• Herbaceous Wind Barrier• Hedgerow planting• Cross Wind Practices
a) Structural Practices
b) Cultural/Agronomical Management PracticesResidue, tillage, nutrient, pesticide and irrigation management
practices and cover crops
c) Long-term conservation cover:
Grass/trees planted on cropland
14
Conservation Practice Scenarios
Scenarios Practice Details Cropland
& CRP (%)
No Practice No practices on cropland 100
Current Conservation
Condition (Baseline)
Current conservation practices
on cropland100
Enhanced Nutrient
Management on Critically
under-treated cropland
(ENMC)
Practices on critically-under
treated area have a high
treatment need 16
Enhanced Nutrient
Management on all
under-treated cropland
(ENMA)
Practices on under treated area
have either a high or moderate
treatment need44
Background Grass-Tree mix grown on
cropland. No cultivated land
contribution
100
US Basin Area (km2) 451,545
Cropland & CRP (km2) 72,250
a) Edge of Field Sediment Loads and Reductions in the Great Lakes Basin
4350
44
5550
15
30
1421
30
47
6254 57 60
0
1
2
3
4
5
6
7
8
Superior Michigan Huron Erie Ontario
Lo
ad
(M
ill.
To
nn
es)
0
20
40
60
80
100
No Practice Baseline ENMC ENMA
Background Baseline Reduction ENMC Reduction ENMA Reduction
b) Edge of Field Nitrogen Loads and Reductions in the Great Lakes Basin
4741
3631
35
45
20 22
8
34
47
37 3832
53
0
50,000
100,000
150,000
200,000
Superior Michigan Huron Erie Ontario
Lo
ad
(T
on
nes)
0
20
40
60
80
100
No Practice Baseline ENMC ENMA
Background Baseline Reduction ENMC Reduction ENMA Reduction
c) Edge of Field Phosphorus Loads and Reductions in the Great Lakes Basin
5350
3532 3432
1510
6
30
4037 38
35
50
0
5,000
10,000
15,000
20,000
Superior Michigan Huron Erie Ontario
Lo
ad
(T
on
nes)
0
20
40
60
80
No Practice Baseline ENMC ENMA
Background Baseline Reduction ENMC Reduction ENMA Reduction
Edge of Field Water Quality Benefits: Conservation Scenarios
Reductions in Edge of Field Loads from Cropland
a) Instream Sediment Load to Great Lakes
1
14
6
10 10
0.34
1 2
7
0.8
10
4 6
11
0
1
2
3
4
Superior Michigan Huron Erie Ontario
Lo
ad
(M
ill
To
nn
es)
0
10
20
30
40
50
No Practice Baseline ENMC ENMA
Background Baseline Reduction ENMA Reduction ENMA Reduction
b) Instream Nitrogen Load to Great Lakes
18
3933
2832
6 813
4
13
6
14
21
1420
0
40,000
80,000
120,000
160,000
200,000
Superior Michigan Huron Erie Ontario
Lo
ad
(T
on
nes)
0
20
40
60
80
100
No Practice Baseline ENMC ENMA
Background Baseline Reduction ENMC Reduction ENMA Reduction
c) Instream Phosphorus Load to Great Lakes
5
33
22
16
11
26 5
2
9
2
12
17 17 16
0
4,000
8,000
12,000
16,000
Superior Michigan Huron Erie Ontario
Lo
ad
(T
on
nes)
0
10
20
30
40
50
No Practice Baseline ENMC ENMA
Background Baseline Reduction ENMC Reduction ENMA Reduction
Instream Water Quality Benefits: Conservation Scenarios
Reductions in Loads Discharged to the Lakes
Conclusions from Assessment on Great Lakes
• Conservation practices reduces field level losses of sediment,
nutrients and pesticides. Benefits of the practices are better
reflected and greater at field level.
• Conservation practices improves water quality of streams and
rivers, lakes and other water bodies in the river basin.
• Targeting critical acres improves effectiveness of conservation
practices significantly.
• Modeling can aid in all of the above processes.
• Modeling system is available to study other emerging issues on
future conservation programs, eutrophication, algae blooms,
climate change, and restoration efforts.
Thank You Thank you !!!
Grazie !!!
Conservation Practices in Great Lakes
Structural Practices % of
Cropland
In field overland flow control practices such as contour farming, strip
cropping, contour buffer strips, terraces, grass terraces and tile drain
9
In field concentrated flow control practices such as grade stabilization
structures, grassed waterways and diversion
12
Edge-of-field buffering and filtering practices such as filter strips,
riparian forest buffers, riparian herbaceous cover and field borders
12
One or more structural practices for water erosion control 26
Wind erosion control practices 4
Cultural Management Practices and CRP
Crop rotation meeting the criteria for no-till or mulch 82
Reduced tillage on some crops in rotation but average annual tillage
intensity greater than criteria for mulch till 9
Continuous conventional tillage in every year of crop rotation 9†All crops in rotations in meeting appropriate rate, timing and method
of nitrogen application 18
Crops in rotations in meeting the appropriate rate, timing and method
of phosphorus application 29
Cover crops <1
Long-term cover establishment/CRP as % of cropland <1
