©2003 institute of water research, all rights reserved water quality modeling for ecological...

©2003 Institute of Water Research, all rights reserved

Water Quality Modelingfor Ecological Services under

Cropping and Grazing Systems

Da OuyangJon Bartholic

Institute of Water ResearchMichigan State University


Water Quality Modeling

Surface Water Quality- Soil Erosion- Sediment Delivery- Nutrient Loading (P, N)

Groundwater Quality- Pesticide / Nutrient Leaching


Water Quality Modeling

Surface Water Quality Modeling- RUSLE- SEDMOD- AGNPS / SWAT- MARI & Nutrient Loading Coefficients

Groundwater Quality Modeling- WIN-PST (Pesticide Screening Tool)


RUSLE

Revised Universal Soil Loss Equation


RUSLE

A = R K LS C P

A = Soil loss in tons per acre per yearR = Rainfall-runoff erosivity factorK = Soil erodibility factorS = Slop steepness factorL = Slope length factorC = Cover-management factorP = Support practice factor


SEDMOD

Spatially Explicit Sediment Delivery Model


Spatially Explicit Sediment Delivery Model (SEDMOD)

SDR = 39 A –1/8 + DP

Where SDR = sediment delivery ratio

A = watershed area in square km

DP = difference between the composite delivery

potential and its mean value


SEDMOD

Delivery Potential composite layer in GRID

DP = (SG)r(SG)w + (SS)r(SS)w + (SR)r(SR)w +

(SP)r(SP)w + (ST)r(ST)w + (OF)r(OF)w

Where SG = slope gradient

SS = slope shape

SR = surface roughness

SP = stream proximity

ST = soil texture

OF = overland flow index

r = parameter rating (1-100)

w = weighting factor (0-1)


Sediment Yield

SY = A * SDR

Where SY = Sediment Yield A = Gross Soil Loss SDR = Sediment Delivery Ratio


WIN-PST

Window-Based Pesticide Screening Tool


WIN-PST(Window-Based Pesticide Screening Tool)

Assess relative likelihood of pesticide loss from - field boundaries via runoff - below the root zone via percolation

Overall risk ratings are based on a matrix of- Pesticide (toxicity, application method and rate)- Soil (Soil texture, hydrologic group, slope, water table)


MARI

Manure Application Risk Index


MARI(Manure Application Risk Index)

Identify areas where winter-time spreading of manure may cause potential risk for runoff losses of N or P

12 Field parameters: Soils; Slope; Soil Test P;

Concentration Water Flow; Residue/Cover;

Surface Water Setback; Vegetative Buffer Width;

Manure P / N Application Rate; Manure Application Method;

Others.


Data

• DEM (Digital Elevation Model, 30-meter)• SSURGO Soil Data (Soil Survey Geographic Database)• Landuse / Land cover data• Crop Residue Management Data (CTIC)• Other - EPA BASINS

Data and Tools for Water Quality Modeling

Previous Studies

Stony Creek Study

Corn-Corn Corn-Soybean Soybean-Wheat

Erosion 182,000 154,000 67,000

Sediment 61,000 52,000 28,000

Phosphorus 129 112 59

Estimated soil loss, sediment and phosphorus inStony Creek Watershed (tons / year)

y = 2.1343x

R2 = 0.9943

0

5

10

15

20

25

30

0 5 10 15

Suspended Solids (ton)

To

tal P

ho

sp

ho

rus (

kg

)

Measured Phosphorus and Suspended SolidsIn Sycamore Creek Watershed, MI

Findings from other study (Randall et al. 1997)

NO3 – losses from row crops (corn, soybean) were 30-50 times greater than losses from perennial crops such as Alfalfa

Atrazine Leaching Risk Mapping

Great Lakes Basin


Estimated Potential Sediment LoadingContributed from Cropland (tons/yr.)

Questions & Discussion

(C = Cover-management factor)

©2003 institute of water research, all rights reserved water quality modeling for ecological...

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