Visualizing alternative pathways for reducing phosphorus ...
Transcript of Visualizing alternative pathways for reducing phosphorus ...
Visualizing alternative pathways for reducing phosphorus loads
into Lake Erie
Rebecca Logsdon Muenich, Margaret Kalcic, Don Scavia
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Motivation
• HABs have become endemic to the western basin of Lake Erie in recent years
• GLWQA has set revised targets to prevent HABs
• Can and how do we achieve these loads?
Maumee
River
Watershed
(MRW)
Western Lake
Erie Basin
Dissolved
Reactive
Phosphorus
(DRP)
186 metric tonnes
40% of 2008 loads
Total
Phosphorus
(TP)
860 metric tonnes
40% of 2008 loads
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Goal & Objectives
• Evaluate extreme land management and land use changes to put bounds on what might be expected from changes in agricultural BMPs.
– (1) Evaluate system response to stopping fertilizer applications
– (2) Evaluate impact of extreme land cover and cropping changes on P loads
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Study Area
• Maumee River Watershed
– Primarily agricultural
– Low sloping topography
– A lot of clay soils
Important SWAT Details:• Fixed bug in SWAT 2012 code to
move P through tiles (~40% coming from tiles)
• Initialized SWAT at lower soil phosphorus conditions than default
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Methods - Scenarios
• System response to stopping fertilizer applications:1. Business as usual
2. No nitrogen or phosphorus fertilizers
3. No phosphorus fertilizers (incl. manure)
4. No inorganic phosphorus fertilizers
• Run under same year’s weather: high spring rainfall, high spring streamflow, average year, dry year
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Methods - Scenarios
• Land management changes
1. Rate of applications: 75%, 50%, 25%, 0% of baseline applications
2. Filter strips: 25%, 50%, 75%, 100% of agricultural lands buffered
3. Cover crops: cover crops added in winter (except when wheat is on) on 25%, 50%, 75%, and 100% of agricultural lands
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Methods - Scenarios
• Land use changes
1. Alternative row crops: continuous sunflower, continuous lentil, and sunflower-lentil rotation
2. Cellulosic biofuel crops: switchgrass and Miscanthus with and without manure applications
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Results – Stopping Fertilizers Applications
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Year from start of simulation Year from start of simulation
Results – Stopping Fertilizers Applications
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Results – Stopping Fertilizers Applications
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Results – Stopping Fertilizers Applications
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Results – Application Reduction
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Results – Filter Strips & Cover CropsFilter Strips
Cover Crops
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Results – Alternative Row Crops
Hig
h P
ho
s.
Med
ium
Ph
os.
Low
Ph
os.
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DRP TP
Results – Perennial Biofuel Crops
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Results - Comparison
DRP
TP
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Conclusions
• BMPs alone may not be enough to reach bothDRP and TP targets
• Scenarios that achieved targets most often were those that reduced P application significantly or completely
• Need a better understanding of soil phosphorus levels
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Extra Slides
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Methods: Model Development
• Model Inputs– 2006 NLCD land use– SSURGO soils– NED DEM– NASS CDL to determine crop rotations– Wetlands & reservoirs added based on NHD medium-
resolution waterbodies– Fertilizer, tillage, and manure applications based on
county level fertilizer sales, NASS animal numbers, and CTIC tillage surveys
– Tile drains on all poorly, very poorly, ands somewhat poorly drained croplands
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Methods: Selecting Years
1980 1985 1990 1995 2000 2005 20100
100
200
300
400
500
600Spring (Mar-July) Precipiation Averaged Across Maumee River Watershed
Year
Pre
cip
ita
tion
(m
m)
1985 1990 1995 2000 2005 20100
50
100
150
200
250
300
350Spring (Mar-July) Streamflow Averaged Across Maumee River Watershed
Year
Str
ea
mfl
ow
(cm
s)
1985 1990 1995 2000 2005 20100
0.5
1
1.5
2
2.5
3
3.5
4x 10
5Spring (Mar-July) DRP Loads @ Waterville
Year
DR
P (
kg
)
1985 1990 1995 2000 2005 20100
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
2.2x 10
6Spring (Mar-July) TP Loads @ Waterville
Year
TP
(kg)
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Methods: Selecting Years
1 2 3 4 5 6 7 8 9 10 11 120
50
100
150
200
250Average Monthly Precipitation in Maumee River Watershed
Month
Pre
cip
ita
tion
(m
m)
Average Year (2004)
1981-2010 data
Highest Spring Precip. (1981)
Dry Year (1988)
Highest Spring Flow (1982)
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Methods: Selecting Years
1 2 3 4 5 6 7 8 9 10 11 120
100
200
300
400
500
600
700
800
Str
ea
mfl
ow
(cm
s)
Average Monthly Streamflow in Maumee River Watershed
Month
Average Year (2004)
1981-2010 data
Highest Spring Precip. (1981)
Dry Year (1988)
Highest Spring Flow (1982)
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Methods: Selecting Years
1 2 3 4 5 6 7 8 9 10 11 120
2
4
6
8
10
12
14
16x 10
5Monthly TP Loads @ Waterville
Month
TP
(kg)
Average Year (2004)
1981-2010 data
Highest Spring Precip. (1981)
Dry Year (1988)
Highest Spring Flow (1982)
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Methods: Selecting Years
1 2 3 4 5 6 7 8 9 10 11 120
2
4
6
8
10
12
14
16x 10
4Monthly DRP Loads @ Waterville
Month
DR
P (
kg
)
Average Year (2004)
1981-2010 data
Highest Spring Precip. (1981)
Dry Year (1988)
Highest Spring Flow (1982)
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