usda, nrcs, watershed science institute watershed ecosystem nutrient dynamics (wend) modeling...

USDA, NRCS, Watershed Science Institute

WATERSHED ECOSYSTEM WATERSHED ECOSYSTEM NUTRIENT DYNAMICS NUTRIENT DYNAMICS

(WEND)(WEND)

Modeling Phosphorus (P) Modeling Phosphorus (P) at a Watershed Scale: at a Watershed Scale:

A Mass Balance ApproachA Mass Balance Approach


WENDWENDA New Tool for Phosphorus (P) A New Tool for Phosphorus (P)

Management Using Off-the-Shelf Management Using Off-the-Shelf SoftwareSoftware

Used to Balance the Input and Used to Balance the Input and Output of P into, out of, and within Output of P into, out of, and within a Watersheda Watershed


Basic Watershed ConceptsBasic Watershed Concepts

Watersheds Store and Cycle P Watersheds Store and Cycle P based on: based on: biological, physical, chemical mechanismsbiological, physical, chemical mechanisms managementmanagement land use development.land use development.

Phosphorus is stored in soils, sediments, Phosphorus is stored in soils, sediments, biomass and wastes.biomass and wastes.


Basic Watershed ConceptsBasic Watershed Concepts

Phosphorus cycles and changes form Phosphorus cycles and changes form due to biological, physical and chemical due to biological, physical and chemical mechanisms.mechanisms.

Phosphorus cycles and changes Phosphorus cycles and changes location within and among land uses location within and among land uses (sectors) within a watershed.(sectors) within a watershed.


Sectors that Process Sectors that Process PhosphorusPhosphorus

AgriculturalAgricultural CroplandCropland PasturePasture Animal OperationsAnimal Operations

Urban and IndustrialUrban and IndustrialWoodlandWoodland


P movement into, out of and P movement into, out of and within these sectors can be within these sectors can be modeled using mass balance modeled using mass balance and dynamic simulation and dynamic simulation techniques.techniques.


Conceptual Conceptual ModelModel


Minnesota

Vermont

Delaware

Oklahoma/Arkansas(cross border)

Four Watersheds Modeled to DateFour Watersheds Modeled to Date


Models Developed for Different Models Developed for Different Land Uses and Animal OperationsLand Uses and Animal Operations

1. The WEND-1 models the 275,000 ha 1. The WEND-1 models the 275,000 ha (679,000 ac) Winooski River Watershed (679,000 ac) Winooski River Watershed in Vermont, USAin Vermont, USA

•DairyDairy

•Silage Corn, Silage Corn, Hay, PastureHay, Pasture



2. The WEND-IBW models the 77,000 ha 2. The WEND-IBW models the 77,000 ha (190,000 ac) Inland Bays Watershed in (190,000 ac) Inland Bays Watershed in Delaware, USA Delaware, USA

•Poultry Poultry

•Corn-Wheat- Corn-Wheat- Soybean Soybean RotationRotation



3. The WEND-LCW models the 23,800 ha 3. The WEND-LCW models the 23,800 ha (58,700 ac) Little Cobb River Watershed (58,700 ac) Little Cobb River Watershed in Minnesota, USAin Minnesota, USA

•Swine Swine

•Oats, Soybeans, Oats, Soybeans, & Corn & Corn



4.The WEND-Eucha models the 93800 ha 4.The WEND-Eucha models the 93800 ha (231,700 ac) Lake Eucha Watershed in (231,700 ac) Lake Eucha Watershed in Arkansas and Oklahoma, USA Arkansas and Oklahoma, USA

•Poultry Poultry

•PasturePasture


Characteristics of Watersheds Characteristics of Watersheds ModeledModeled

Characteristic Winooski Inland Bays Little Cobb Eucha

Land Area (ha) 275,000 77,000 24,000 94,000

% Urban 8 12 2 < 1

% Agriculture 13 36 93 43

% Forested 74 24 3 55

% Water, Other 5 28 2 2

Overall Terrain Hilly,Mountains

Flat, HighlyDrained

Gently RollingDrained

Hilly


Characteristics of Watersheds Characteristics of Watersheds ModeledModeled

Characteristic Winooski Inland Bays Little Cobb Eucha

ResidentPopulation(No.)

153,000(Est. 1995)

36,000(Est. 1998)

1,500(est. 2000)

2,500 (est. 2001)

Tourism(visitor-days/year)

300,000(est. 1995)

5,200,000(est. 1998)

N/A N/A

DominantAnimal

Cattle (dairy) Poultry(broilers)

Swine Poultry(broilers)

Animal Units(No.)

76,000 130,000 127,000 180,000

DominantAgriculturalLand

Silage Corn,Hay, Pasture

Corn-Wheat-SoybeanRotation

Oats-Soybeans-

Corn

Pasture


PRESENT CONDITIONS

0

20,000

40,000

60,000

80,000

100,000

120,000

140,000

160,000

180,000

0 5 10 15 20 25 30 35

Years

Kg

P t

o D

rain

ag

e N

et

Winooski PresentConditions

Inland Bays PresentConditions

Little Cobb RiverPresent Conditions

Eucha PresentConditions


Monitored Data vs. Modeled Monitored Data vs. Modeled EstimatesEstimates

Watershed P to DrainageNet Monitored

(kg/ha)

P to Drainage Netfrom WEND Model

(kg/ha)

Winooski .56 .54

Inland Bays N/A .75

Little CobbRiver

.44 .47

Eucha .51 .51


Management AlternativesManagement AlternativesSimulated with WENDSimulated with WEND

Erosion Control Erosion Control

Manure Export Manure Export


Management AlternativesManagement AlternativesSimulated with WENDSimulated with WEND

Increased Treatment of Point Increased Treatment of Point SourcesSources

Animal ReductionAnimal Reduction


AG EROSION REDUCTION SCENARIOS

0

20,000

40,000

60,000

80,000

100,000

120,000

140,000

160,000

180,000

0 5 10 15 20 25 30 35

Years

Kg

P t

o D

rain

age

Net


Winooski 15%Reduction


Inland Bays 15%Reduction


Little Cobb River 15%Reduction


Eucha 15% Reduction


MANURE EXPORT SCENARIOS

0.00

20,000.00

40,000.00

60,000.00

80,000.00

100,000.00

120,000.00

140,000.00

160,000.00

180,000.00

0 5 10 15 20 25 30 35

Years

Kg

P t

o D

rain

age

Net


Winooski Export 50%


Inland Bays Export50%


Little Cobb RiverExport 50%


Eucha Export 50%


INCREASED LEVELS of DOMESTIC WASTEWATER TREATMENT SCENARIOS

0.00

20,000.00

40,000.00

60,000.00

80,000.00

100,000.00

120,000.00

140,000.00

160,000.00

180,000.00

Years

Kg

P t

o D

rain

ag

e N

et


Winooski P Increase DomWaste Treat by 50%


Inland Bays IncreaseDom Waste Treat by 50%

Little Cobb PresentConditions

Little Cobb Increase DomWaste Treat by 50%


Eucha Increase DomWaste Treatment by 50%


REDUCE ANIMAL POPULATION to ZERO

0.00

20,000.00

40,000.00

60,000.00

80,000.00

100,000.00

120,000.00

140,000.00

160,000.00

180,000.00

0 5 10 15 20 25 30 35

Years

Kg

P t

o D

rain

age

Net


Winooski RemoveAnimals


Inland Bays RemoveAnimals


Little Cobb RiverRemove Animals


Eucha RemoveAnimals


ConclusionsConclusions

WEND Models Are Valid For WEND Models Are Valid For Evaluating P Management Evaluating P Management Scenarios For WatershedsScenarios For Watersheds

P Management Strategies Must Be P Management Strategies Must Be Tailored To Fit Conditions in a Tailored To Fit Conditions in a Individual WatershedIndividual Watershed


ConclusionsConclusions

P Sources Change Over TimeP Sources Change Over Time

A Reduction in Non-Point Source P A Reduction in Non-Point Source P Export to a Drainage Net May Take Export to a Drainage Net May Take YearsYears


For Additional InformationFor Additional Information

David Anderson

NRCS Watershed Science Institute

402-437-5178x46

[email protected]

usda, nrcs, watershed science institute watershed ecosystem nutrient dynamics (wend) modeling...

Documents

individual watershed

watershed scale

corn slide

date slide

ac winooski river watershed

ac lake eucha watershed

soybean rotation slide

ac inland bays watershed