sparrow modeling case study
DESCRIPTION
SPARROW Modeling Case Study. By Jahangir Alam and Jonathan Goodall Dept of Civil Engineering University of South Carolina. Research Question: What is the impact of land use change in the U.S. from 1992 to 2001 on nitrogen delivery?. Observations Database: 400 sites. - PowerPoint PPT PresentationTRANSCRIPT
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SPARROW Modeling Case Study
Research Question: What is the impact of land use change in the U.S. from 1992 to 2001 on nitrogen delivery?
By Jahangir Alam and Jonathan GoodallDept of Civil EngineeringUniversity of South Carolina
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Observations Database: 400 sites
For each NAWQA site where flow and concentration are available for time period of interest, relate spatially-referenced watershed characteristics to observed in-stream load.
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SPARROW Equations
TNi = observed nitrogen loading at station iSn,j = nitrogen source n for reach jZj = watershed attributes for reach jTi,j = travel time from reach j to station iβn , α, and k = calibration parameters
Smith, R.A., Schwarz, G.E., and Alexander, R.B., 1997, Regional interpretation of water-quality monitoring data, Water Resources Research, 33, 12, 2781-2798.
http://water.usgs.gov/nawqa/sparrow
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SPARROWSPARROW considers tobasic processes innitrogen transport:
(1.) Overland transport (2.) In-stream transport
(both are assumed tofollow 1st order decay)
Overland Transport
In-stream Transport
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Eno River Basin
Little Creek
SPARROW Calibration
Nitrogen Observation Site
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Example of Previous SPARROW Application: Nitrogen Transport to the Gulf
Agriculture Atmosphere
Point Sources
Alexander, R.B., Smith, R.A., and Schwarz, G.E., 2000, Effect of stream channel size on the delivery of nitrogen to the Gulf of Mexico, Nature, 403, 758-761.
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Procedure
1. Prepare land cover data2. Prepare loading data3. Update “baseline” SPARROW inputs with
1992 and 2001 specific data
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Procedure
1. Prepare land cover data2. Prepare loading data3. Update “baseline” SPARROW inputs with
1992 and 2001 specific data
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National Land Cover Dataset (NLCD)
• Products include classifications for 1992, 2001, and 2006 (in development), and change product (1992 to 2001)• 30m resolution; 25 classes • http://www.epa.gov/mrlc
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Urbanization in Columbia, SCChange Product (1992 to 2001)
map of NLCD 2001
Colored Pixels are 2001 NLCDBlack Pixels Change to Urban from 1992 to 2001
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Urbanization in Charlotte, NCChange Product (1992 to 2001)
map of NLCD 2001
Colored Pixels are 2001 NLCDBlack Pixels Change to Urban from 1992 to 2001
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Land Cover Change in the South East U.S.
* all areas reported in units of km2
from
to Open Water Urban Barren Forest Grassland/Shrub Agriculture Wetlands Ice/Snow sum
Open Water - 82 26 194 13 190 244 0 749
Urban 33 - 2 2,563 185 720 591 0 4,094
Barren 46 7 - 350 23 71 75 0 572
Forest 30 127 7 - 4,032 5,111 401 0 9,707
Grassland/Shrub 118 55 7 13,961 - 481 782 0 15,404
Agriculture 72 171 4 6,606 701 - 820 0 8,373
Wetlands 477 92 11 1,879 411 996 - 0 3,866
Ice/Snow 0 0 0 0 0 0 0 - 0
sum 775 451 31 25,359 5,352 7,379 2,668 0
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Land Cover Change in South East U.S.(1992 to 2001)
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Summarizing Land Cover
1992
2001
WatershedID Urban
1 534322
2 453221
… …
Modeling Units
WatershedID Urban
1 534322
2 453221
… …
1992 2001
61,215 Watersheds
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Procedure
1. Prepare land cover data2. Prepare loading data3. Update “baseline” SPARROW inputs with
1992 and 2001 specific data
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Data Preparation Workflow
Time Series Data
Identify time series of interest
Create sites.csv file
Run FetchWaterML.exe
tool to create WaterML Cache
Reformat files from WaterML to LOADEST inputs
Runkel, R.L., Crawford, C.G., and Cohn, T.A., 2004, Load Estimator (LOADEST): A FORTRAN Program for Estimating Constituent Loads in Streams and Rivers: U.S. Geological Survey Techniques and Methods Book 4, Chapter A5, 69 p.
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Creating a Cache of HIS DataSites.csv
c:> FetchWaterML.exe sites.csv ./daily-discharge-2/
output directoryinput sites file
Downloaded WaterML Files (one for each time series requested)
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Estimating Load from Flow and Concentration
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TN Loading Data
1988-1996
< 5.0x106
5.0x106 - 10.0x106
10.0x106 - 20.0x106
20.0x106 - 50.0x106
> 50.0x106
Average Loading (kg/yr)
1997-2005
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Difference, ‘92 and ‘01 Loadings
> - 5.0x106
-5.0x106 - 00 - 5x106 > 5.0x106
Loading Difference (kg/yr)
+ (orange/red) increase in loading from 92 to 01- (blue) decrease in loading
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Procedure
1. Prepare land cover data2. Prepare loading data3. Update “baseline” SPARROW inputs with
1992 and 2001 specific data
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Results
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Results
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Conclusions • Our model suggests that nitrogen loadings to streams have
decreased from the 1990s to the 2000s by on average 1 kg/ha/yr (or roughly 10%). It also shows a shift in the relative contribution of nitrogen sources with a greater contribution from urban land use areas in the 2000s compared to the 1990s. That said, the current model assumes fertilizer application rates, point sources loadings, and animal populations are constant over time because it is difficult to obtain differences between these numbers of the two time periods of analysis.