visualizing alternative pathways for reducing phosphorus
TRANSCRIPT
Visualizing alternative pathways for reducing phosphorus loads
into Lake Erie
Rebecca Logsdon Muenich, Margaret Kalcic, Don Scavia
1
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
2
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
3
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
4
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
5
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
6
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
7
Results – Stopping Fertilizers Applications
8
Year from start of simulation Year from start of simulation
Results – Stopping Fertilizers Applications
9
Results – Stopping Fertilizers Applications
10
Results – Stopping Fertilizers Applications
11
Results – Application Reduction
12
Results – Filter Strips & Cover CropsFilter Strips
Cover Crops
13
Results – Alternative Row Crops
Hig
h P
ho
s.
Med
ium
Ph
os.
Low
Ph
os.
14
DRP TP
Results – Perennial Biofuel Crops
15
Results - Comparison
DRP
TP
16
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
17
Extra Slides
18
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
19
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)
21
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)
22
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)
23
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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