SPARROW Modeling in the Mississippi and Atchafalaya River Basins (MARB) Dale Robertson, Richard Alexander, and David Saad U.S. Geological Survey USGS/USEPA.

SPARROW Modeling in the Mississippi and Atchafalaya River Basins (MARB)

Dale Robertson, Richard Alexander, and David Saad

U.S. Geological Survey

USGS/USEPAWEBEX Meeting

June 29, 2007

Outline• Overview of SPARROW

• Recent advances in SPARROW and applications to the Mississippi/Atchafalaya R. Basin

• Summary of nitrogen and phosphorus results for large regional basins

• Preliminary watershed rankings – nutrient delivery to the Gulf

• Future SPARROW modeling

SPARROW Water-Quality ModelSPAtially Referenced Regression on Watershed Attributes

http://water.usgs.gov/nawqa/sparrow; Smith et al. 1997

Hybrid statistical and mechanistic process structure; mass-balance constraints; data-driven, nonlinear estimation of parameters

Spatially explicit; separates land and water processes

Physically interpretable coefficients; model supports hypothesis testing and uncertainty estimation

Predictions of mean-annual flux reflect long-term, net effects of nutrient supply and loss processes in watersheds

Sources

Land-to-watertransport

SPARROW modeling approach:- Regress water-quality conditions (monitored load) on upstream sources and factors controlling transport- Incorporates instream decay of nutrients

Monitored load

Instreamtransport

Nonlinear Regression Model

SPARROWSPAtially Referenced Regressions On Watershed Attributes

For each watershed

Estimation of mean-annual nutrient load

at stream monitoring sites – Model Inputs

Log

Load

(k

g/da

y)

1992 Base YearActual LoadPredicted Load

Load Confidence Interval

1978

1982

1986 19

9019

9419

76 1980 19

8419

8819

92

Mean-annual TN load for 1992 base year (detrended; flow-adjusted 1975-2000)

SPARROW’s Reach-Scale Mass Balance

Reach network relates watershed datato monitored loads

Load leaving a reach =

Load generated within upstream reaches and

transported to the reach via the stream network

+

Load originating within the reach’s incremental watershed and delivered

to the reach segment

Earlier SPARROW ResultsEarlier SPARROW ResultsTotal Nitrogen Delivery to the Gulf of MexicoTotal Nitrogen Delivery to the Gulf of Mexico

1987 Base Year1987 Base YearAgriculture Municipal Wastewater

Atmosphere

Alexander et al. 2000, Nature

• Model structure: specification, flux-routing algorithms, stream monitoring loads, documentation

• Data infrastructure: climate, 1-km DEM, 30-m NLCD land use, cropping and drainage systems

• Result:• Added complexity• Model accuracy

improved by 20%

Recent Advances in SPARROW

ClimateWatersheds

Topography

Land Use

Water

Ice, snow

High intensity residential

Low intensity residential

Quarries, strip mines, gravel pits

Transitional

Bare rock, sand, clay

Commercial, industrial, transportation

Deciduous forest

Mixed forest

Evergreen forest Grasslands, herbaceous

Pasture, hay

Orchards, vineyards, other

Shrubland Row crops

Small grains

Urban, recreational grasses

Fallow

Emergent herbaceous wetlands

Woody wetlands

NLCD 1K

Artificial Drainage

SPARROW Sources andTransport Features

NUTRIENT SOURCES (1992)•Urban and population sources•Atmospheric N deposition•Farm fertilizer use allocated to

major crops:– County fertilizer sales and

expenditures; crop acreage– NLCD agricultural land use– State application rates (corn,

soybeans, cotton, wheat, other crops)

– Corn/soybean rotations•N2 fixation – cultivated lands•Animal manure:

– Non-recoverable on pasture/rangelands

– Recoverable on crops•Natural and residual sources

(lands in forest, barren, shrub)

AQUATIC ATTENUATION•Streams

– First-order decay ~ f(water travel time, flow and depth)

•Reservoirs– First-order decay ~ f(areal

hydraulic load—ratio of outflow to surface area)

LAND-TO-WATER DELIVERY•Climate (precipitation,

temperature)•Soils (permeability)•Topography/subsurface (slope,

specific catchment area)•Artificial drainage (tiles,

ditches)

SPARROW Delivery of Agricultural Nutrients to Streams

CROPNUTRIENTS

COMMERCIAL FERTILIZER

BIOLOGICALN2 FIXATION

ANIMAL MANURE(Non-recoverable)

UNCONFINED ANIMALS

RECOVERABLEMANURE

CONFINED ANIMALS

Model Source &Delivery Coefficients

Model Source &Delivery Coefficients

STREAMS & RESERVOIRS

N

P

Harvesting

The Improved SPARROW Nutrient Models

Observed vs. Predicted Yield

Stream and Reservoir Transport for 1992

SPARROW Rates of Aquatic Nutrient Loss

Nutrient removal rate declines in larger riversand more rapidly flushed reservoirs

Nitrogen literature rates from Howarth et al. 1996; Seitzinger et al. 2002; Bohlke et al. 2004; Mulholland et al. 2004)

STREAMS RESERVOIRS

Percentage of Stream Nutrients Delivered to the Gulf of Mexico

Total Nitrogen Total Phosphorus

Remove1 kg at Gulf outlet

Remove1.1 kg = 1/0.9

Remove4 kg = 1/0.25

Aquatic Removal of Nutrients in MARB Regional Watersheds - 1992

Regional Watersheds

Nutrient Source Contributions

to Stream Flux:Types and Regional

Geography

Sources Contributions to Stream Nutrient Flux - 1992

Mississippi River at St. Francisville, LA

Regional Contributions to the Stream Nutrient Flux to the Gulf of

Mexico - 1992Regional Watersheds

Changes in Stream Nutrient Flux, 1992 to

2002•Simulate changes in flow-adjusted stream nutrient flux

•Account for changes in population and agriculture (animal manure; crop fertilizer application, acreage, and production)

•Account for changes in harvested nutrients with changes in marginal rate of crop production

•Assume steady-state conditions with constant model coefficients over time

Simulated Changes in Flow-Adjusted Nutrient Flux, 1992 to

2002

•Changes in flux typically less than 5%

•Geography of 2002 source shares are generally unchanged from 1992

*statistically sig. (p<0.06)

MARB Watershed Rankings

Nutrient Delivery to the Gulf of Mexico for 1992

Preliminary watershed rankings based on nutrient delivery to the Gulf

Try to answer questions that have been popping up during past discussions.

Future SPARROW modeling- Additional Refinements to the SPARROW models

Definitions:Load – Total amount of a constituent transported – (kgs)

Incremental Yield – Amount of a constituent transported per unit area between two points – kg/km2

Delivered Incremental Yield – Amount of a constituent transported per unit area between two points that is delivered or transported to some specific point – kg/km2

Yield – Total amount of a constituent transported per unit area – kg/km2

Total Nitrogen Load – Compare with Monitoring Data

- Can be used to estimate instream concentrations

Top 4 %

1992 Nitrogen SPARROW Model Output

Total Nitrogen – Incremental Yield- Can be used to demonstrate the highest export areas


Total Nitrogen – Incremental YieldTop 10 %


Total Nitrogen – Delivered Incremental Yield to the Gulf


Total Nitrogen – Delivered Incremental Yield to the Gulf

Top 10 %


Total Nitrogen – Delivered Incremental Yield

HUC 8 Scale



Top 100

Top 100 represent 42% of the Total Load


Top 100


Ranked Top 100HUC 8’s

Total Nitrogen – Ranked based on total delivered incremental yield


Rank HUC HUC NAME STATES Area (km2)

Total Nitrogen Incremental Load (kgs)

Delivered Incremental Yield (kg/km2)

1 7120003 Chicago IL IN 1,256 6,561,711 5,224.32 5120205 Flatrock-Haw IN 1,101 3,162,907 2,872.83 8020201 New Madrid-St. Johns KY MO 1,340 3,828,405 2,857.04 5120113 Lower Wabash IL IN KY 3,303 9,075,317 2,747.65 5120107 Wildcat IN 1,898 5,088,816 2,681.16 5120206 Upper East Fork White IN 2,246 5,719,073 2,546.37 7120005 Upper Illinois IL 2,482 5,875,363 2,367.28 5140202 Highland-Pigeon IN KY 2,707 6,403,427 2,365.59 5120204 Driftwood IN 2,872 6,759,048 2,353.410 5120105 Middle Wabash-Deer IN 1,828 4,260,060 2,330.4


1,500 km2

HUC8 MRB3 National

Types of Basins

101

102

103

104

105

106A

rea

(km

2)

SPARROW Calibration Basins

160 km2207 km2

5th Percentile

3,200 km2

SPARROW Median Basin Size

86 km2

10% <12 km2

Best to predict for Basins > 200 km2

0

200,000,000

400,000,000

600,000,000

800,000,000

1,000,000,000

1,200,000,000

1,400,000,000

1,600,000,000

0 100 200 300 400 500 600 700 800

Ranked HUCs

To

tal N

itro

ge

n L

oa

din

g, k

gs

0%

20%

40%

60%

80%

100%

Incremental Load

Accumulated Nitrogen Loading


To Obtain a 30% Reduction in the Total Nitrogen Load

Number of Basins (HUC 8) Required to Aquire Specific Nitrogen Load Reductions to the Gulf

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0 100 200 300 400 500 600 700 800Number of Basins Required to Achieve Reduction

Pe

rce

nt

Re

du

cti

on

to

th

e G

ulf

0

200,000,000

400,000,000

600,000,000

800,000,000

1,000,000,000

1,200,000,000

1,400,000,000

1,600,000,000

To

tal P

os

sib

le L

oa

d R

ed

uc

tio

n,

Kg

s

100% Removal in HUC90%80%70%60%50%40%30%20%10%

With a 100% Removal in TN Load, it would require the top 68 HUCs

With a 50% Removal in TN Load, it would require the top 171 HUCs

Total Phosphorus Loading

Top 4 %

1992 Phosphorus SPARROW Model Output

Total Phosphorus – Delivered Incremental Yield

Top 10 %



HUC 8 Scale



HUC 8 ScaleTop 100

Top 100 > 42% of the Total Load


HUC 8 ScaleTop 100



Total Phosphorus – Ranked based on total delivered incremental yield

Rank HUC HUC NAME STATES Area (km2)

Total P Incremental Load (kgs)

Delivered Incremental Yield (kg/km2)

1 7120003 Chicago IL IN 1,256 633,967 504.7502 8020201 New Madrid-St. Johns KY MO 1,340 403,649 301.2303 5120101 Upper Wabash IN OH 4,606 1,226,551 266.2944 8020204 Little River Ditches AR KY MO 6,336 1,617,929 255.3555 8030207 Big Sunflower AR MS 6,956 1,687,703 242.6266 8030209 Deer-Steele AR LA MS 1,863 434,846 233.4127 5100102 South Fork Licking KY 2,391 540,428 226.0268 8070100 Lower Mississippi-Baton Rouge LA 2,292 464,357 202.5999 8090100 Lower Mississippi-New Orleans LA 1,583 311,200 196.58910 5120206 Upper East Fork White IN 2,246 441,432 196.541



0

20,000,000

40,000,000

60,000,000

80,000,000

100,000,000

120,000,000

140,000,000

0 100 200 300 400 500 600 700 800

Ranked HUCs

To

tal P

ho

sp

ho

rus

Lo

ad

ing

, kg

s

0%

20%

40%

60%

80%

100%

Incremental Load

Accumulated Phosphorus Loading


Number of Basins (HUC 8) Required to Aquire Specific Phosphorus Load Reductions to the Gulf

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

110%

0 100 200 300 400 500 600 700 800Number of Basins Required to Achieve Reduction

Pe

rce

nt

Re

du

cti

on

to

th

e G

ulf

0

20,000,000

40,000,000

60,000,000

80,000,000

100,000,000

120,000,000

140,000,000

To

tal P

os

sib

le L

oa

d R

ed

uc

tio

n,

Kg

s

100% Removal in HUC90%80%70%60%50%40%30%20%10%

To Obtain a 30% Reduction in the Total Phosphorus Load

With a 100% Removal in TP Load, it would require the top 70 HUCs

With a 50% Removal in TP Load, it would require the top 162 HUCs

U.S. Geological Survey SPARROW modelsNational Model – Richard Alexander, G. Schwarz, and R. Smith

1992 and 2002 Models

Dale Robertson, WI

Richard Rebich, MS

Lori Sprague, CO

Major River BasinLead MRB Scientists

Anne Hoos, TN

Richard Moore

Mississippi River SPARROW Model

Dale Robertson, WI

Richard Rebich, MS

Lori Sprague, CO

Mississippi River SPARROW Coordinator: Dale Robertson

Richard Alexander, VA

Future Improvements from Regional SPARROW Models

1. Better spatial resolution – More sites and especially more smaller sites, should lead to more accurate predictions at smaller scales.

2. Further reductions in biases.

3. Better definition of source terms – better point-source data, more sites in unique areas, possible better local GIS inputs.

4. Better able to address more regional and local questions.

Approximately 475-600 sites used in National SPARROW Models(Number of sites used in models varies by constituent)

~1000 Potential Load Sites for MRB3 SPARROW Model

WQ Data: -NWIS -STORET -States (IN,IL, WI)

Flow Data: -NWIS

Potential load site

EXPLANATION

Additional Sites to be Added for Model Calibration

~1000 Potential Load Sites for MRB3 SPARROW ModelPotential Sites in the Missouri River Basin

~350 sites~750-1000 sites in the Lower Mississippi River Basin

Standardized Residuals Map for Total Phosphorus Further Reduction in Spatial Biases

Standardized Residuals

Refinement of Source Contributions to Stream Nutrient Flux

Mississippi River at St. Francisville, LA

Better able to address more regional and local questions

SPARROW Modeling in the Mississippi and Great Lakes Basins

Captain Jack Sparrow

SPARROW Modeling in the Mississippi and Atchafalaya River Basins (MARB) Dale Robertson, Richard Alexander, and David Saad U.S. Geological Survey USGS/USEPA.

Documents

watershed slide

time slide

nature slide

streamsreservoirs slide

sparrow sources

load instream transport

regional geography slide

stream flux