Download Modeling the effects of precipitation events on nutrient loading in

Modeling the effects of precipitation
events on nutrient loading in Munroe
Brook, Shelburne, VT
VT EPSCoR Streams Project
April 2009
Nichole Bushey & Meredith Simard
Modeling vs. Monitoring
• Crucial to address issues of water quality from a
watershed perspective
• Monitoring
▫ Provides information about the current state of
the watershed
▫ Costly and time-consuming
• Modeling
▫ Predicts changes resulting from future conditions
▫ Tests future alternative scenarios
Watershed Details
• Drains into Shelburne Bay
• Watershed area: 1435.46 ha
(3547.01 acres)
• 85 ha high density urban
• 121ha low density urban
• 281 ha agriculture
• Total stream length: 28.6 km (17.8
miles)
Sampling Details
• 12 sample sites named by tributary
• T1
• T2
• M
• Focus at M1
AVGWLF & PRedICT
• ArcView Generalized Watershed Loading
Function
▫ Monthly outputs of sediment and nutrient loads
based on daily discharge
▫ Advantages:
 “Mid-Level” model
 Ease of use
 Less complex input datasets
• Pollution Reduction Impact Comparison Tool
▫ Evaluates implementation of urban and rural
pollution reduction strategies at watershed level
Modeling Process
• Locate and create input data
• Simulate discharge and nutrient loads and
compare with sample data from 2006 and 2007
sampling seasons
▫ Calibration
• Scenarios
▫ Current status
▫ Future precipitation and temperature associated
with climate change
▫ Future land management
Calibrating the Model:
Discharge
Discharge (cms)
Average Daily Discharge per Month
2006
0.6
Stream Gauge
0.4
Original Model Output
0.2
Calibrated Model Output
0
1
2
3
4
5
6
Month (June- Novem ber)
Discharge
(cms)
Changed 630 ha
of Row Crops to
Golf Course to
better match
watershed
landuse.
Average Daily Discharge per Month
2007
0.6
Stream Guage
0.4
Original Model Output
0.2
Calibrated Model Output
0
1
2
3
4
Month (June- Novem ber)
5
6
Calibrating the Model:
Nutrients
2007 Total Nitrogen: Modeled v. Actual Data
TN Load (g/sec)
1
0.8
Actual Data
0.6
Original Model Output
0.4
Calibrated Model Output
0.2
0
1
2
3
4
5
Month (June-November)
2007 Total Phosphorus: Modeled vs. Actual Data
TP Load (g/sec)
0.025
0.02
Actual Data
0.015
Original Model Output
0.01
Calibrated Model Output
0.005
0
1
2
3
4
Month (June-November)
5
6
6
Climate Change Scenarios:
Parameters
• Lower Emissions Scenario for
2069
▫ Average annual temperature
increase of 3.7°F
▫ 11% increase in winter
precipitation
• Higher Emissions Scenario for
2069
▫ Average annual temperature
increase of 5.8°F
▫ 16% increase in winter
precipitation
• Increase in frequency of droughts
• Increase in likelihood and severity of heavy rainfall events
• Increase in winter precipitation falling as rain and 25-50% decrease
in snowfall by the end of the century
• Increasing period of low streamflow due to higher temperature and
increased evapotranspiration.
Climate Change Scenarios:
Hydrological Results
Evapotranspiration predictions for 2069
12
ET (cm)
10
8
Current emissions
6
Low emissions
4
High emission
2
0
1
2
3
4
5
6
7
8
9
10 11 12
Month (January-December)
Effects of climate change on discharge
Discharge (cms)
0.7
0.6
0.5
Current emissions
0.4
Low emissions
0.3
High emissions
0.2
0.1
0
1
2
3
4
5
6
7
8
9
10
Month (January-December)
11
12
Total Phosphorus (g/sec)
Climate Change Scenario:
Nutrient Results
Total Phosphorus Loading
0.09
0.08
0.07
0.06
0.05
0.04
0.03
0.02
0.01
0
Low Emission
Scenario
High Emission
Scenario
Current Emissions
1
2
3
4
5
6
7
8
9 10 11 12
Month (January - December)
Total Nitrogen Loading
Total Nitrogen (g/sec)
1
0.8
Low Emission
Scenario
0.6
High Emission
Scenario
0.4
Current Emissions
0.2
0
1
2
3
4
5
6
7
8
9
10 11 12
Month (January-December)
Watershed Improvements
Stream Bank Fencing
Vegetated Buffers
Rain Garden
Vegetated Buffers
940m of stream length
1190m of stream length
Rain Garden Installation
0.6 ha of rain gardens will drain just over 5 ha of impervious surface
Stream Bank Fencing
• Cows negatively impact:
• water quality
• streambank stability
• Goal: Protect 300m of stream
bank from livestock
Improving our Study
• Improve accuracy of landuse layer
• Additional Input data
▫ Septic systems
• Compare tributaries to whole watershed
• Alternative and more comprehensive scenarios
▫ Climate change predictions based on multi-year
averages
▫ Urban watershed management practices
▫ Further utilization of PRedICT software
Acknowledgements
•
•
•
•
Maeve McBride
KathiJo Jankowski
Meredith Curling (UVM)
Bill Hoadley (LaPlatte Watershed Partnership)