linking field and watershed runoff and water quality

F. Ghidey, C. Baffaut, R. Lerch, and E. J. Sadler

Goodwater Creek Experimental Watershed (GCEW)

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Salt River Basin

GCEW

Weir 1

Field 2

Field 1

Goodwater Creek Experimental Watershed (GCEW)

GCEW is a 7263 ha (17946 ac) located in the claypan soil

region of north-central Missouri.

It’s mainly an agricultural area: 75% cropland, 14%

pasture, 7% forestland, 5% urban, and 1% water.

Major Soil type is Mexico Silt loam characterized by

naturally occurring argillic claypan horizon located 15 to

45 cm below the surface. The clay content of the argillic

horizon is > 50%.

Claypan soils are considered to be poorly drained.

Watershed Scale Data

Flow data from 1971 to present.

Water quality monitoring at GCEW started in 1992:

Dissolved nutrients

Herbicides

Suspended Sediment

Field Scale Data

Field 1 – (1993 – 2002) 34.4 ha (84.9 ac) area

Mulch tillage corn-soybean rotation. Herbicide and fertilizers surface applied and incorporated during the corn

years.

Flow, herbicides, dissolved nutrients, and suspended solids measured during the study period.

Field 2 (1997 -2001) 7.8 ha (19.2 ac) area.

No-till corn-soybean rotation Herbicide and P fertilizer surface applied and not incorporated.

N injected.

Flow, herbicides, dissolved nutrients, and suspended solids measured during the study period.

Objective

To analyze and link runoff and water quality measured from field and watershed scales located within the Goodwater Creek Experimental Watershed (GCEW).

How do we analyze and link measured field

and watershed data?

Percent of herbicide and fertilizer applied lost to runoff.

Flow and load duration curves.

Annual loads and Percent Losses

Runoff, herbicide and nutrient concentrations are

measured on a sub-daily basis.

Daily, monthly, and annual loads (g/ha) are computed

based on the measured runoff and corresponding herbicide

and nutrient concentrations.

Annual load data are analyzed to estimate losses as

percent of total fertilizer and herbicides applied during the

study period.

Average Annual Runoff (1997-2002)

Growing Season (GS, Apr-Oct) Non-Crop Crowing season (NCGS, Nov-Mar)

F1 Mulch F2 No-Till GCEW Surf GCEW Total

Ru

no

ff (

mm

)

0

50

100

150

200

250

300

• During the GS, average annual flow between the fields and GCEW was not significantly

different (p=0.1).

• During the NCGS, average annual flow between fields and GCEW was also not

significantly different, however, Baffaut et al. (JEQ, 2015) showed there was a significant

difference between runoff from the no-till field (F2) and tilled field (F1) at the event

scale. F2 flow was 20% less than F1 flow.

a aa

a

F1 Mulch F2 No-Till GCEW Surf GCEW TotalR

un

off

(m

m)

0

50

100

150

200

250

300

aa

aa

Applied Atrazine Lost to Runoff (1997 – 2001)

Growing Season (GS, Apr-Oct) Non-Crop Crowing season(NCGS, Nov-Mar)

F1 Mulch F2 No-Till GCEW

Atr

azin

e A

pp

lie

d L

os

t to

Ru

no

ff (

%)

0

1

2

3

4

5

6

7

F1 Mulch F2 No-Till GCEWA

tra

zin

e A

pp

lie

d L

os

t to

Ru

no

ff (

%)

0

1

2

3

4

5

6

7

• Atrazine loss from the no-till and GCEW was ~ 4 times greater than from the mulch tillage

system.

• This implies that, overall in the watershed, atrazine was broadcast and not

incorporated.

• Almost all atrazine losses occurred during the GS.

aa

b

Applied Nitrogen Lost to Runoff (1997 – 2001)

Growing Season (GS, Apr-Oct) Non-Crop Crowing season(NGS, Nov-Mar)


Nit

rog

en

Ap

plie

d L

os

t to

Ru

no

ff (

%)

0

2

4

6

8

10

12

14


Nit

rog

en

Ap

plie

d L

os

t to

Ru

no

ff (

%)

0

2

4

6

8

10

12

14

• Nitrogen –Dissolved N (88 - 94% NO3-N, 6 – 12% NH4-N).

• Most losses from the fields occurred during the GS.

• Average annual N loss from Mulch tillage (F1) and GCEW was 3 times greater

than from the No-till system (F2). N was injected at F2.

ab

c

a

bb

Applied Phosphorus Lost to Runoff (1997 – 2001)

Growing Season (GS, Apr-Oct) Non-Crop Crowing season(NCGS, Nov-Mar)


Ph

os

ph

oru

s A

pp

lie

d L

os

t to

Ru

no

ff (

%)

0

2

4

6

8

F1 Mulch F2 No-Till GCEWP

ho

sp

ho

rus

Ap

plie

d L

os

t to

Ru

no

ff (

%)

0

2

4

6

8

• Phosphorus was not applied at F1 (1997 – 2000) because soil P was high.

• During the NCGS, average annual dissolved-P loss from F2 was significantly

less (p=0.1) than from GCEW.

• At the watershed level, dissolved-P loss during the GS and NCGS was similar.

a

b

aa

Average Annual Sediment Yield (1997 – 2001)

Growing Season (GS, Apr-Oct) Non-Crop Crowing season (NCGS, Nov-Mar)


Se

dim

en

t L

oa

d (

T/h

a)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

F1 Mulch F2 No-Till GCEWS

ed

ime

nt

Lo

ad

(T

/ha

)0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

• Average annual sediment load from the tilled field was 3 times greater than form

the no-till field.

• Average annual sediment load from GCEW was also low compared to field 1

probably due to several processes that happen between the edge-of-field and the

watershed outlet: sediment deposition, stream bank erosion.

Load Duration Curves

Estimating percent of applied fertilizer lost to runoff does

not include the contribution of point sources in a

watershed.

Load duration curves can help identify possible point

source-contributions.

Load duration curves can also be used to separate surface

and subsurface herbicide and nutrient losses.

How do we develop load duration curves?

First we develop the flow duration curve.

Next we plot daily loads against daily flow duration.

Flow Duration Curve

Relates daily flow values to the frequency at which these values have been met or exceeded: Rank measured daily flow from highest to lowest

Compute frequency using the formula 𝑝 = ((𝑀 − 0.4)/(𝑁 − 0.2))*100

Where:

p: frequency at which a given flow will be equaled or exceeded

M: rank of the event

N: total number of events

Plot flow duration curve: daily discharge versus frequency of exceedance (flow duration interval).

Plot load duration curve: daily load versus frequency of the corresponding daily flow.

An Example of Flow duration curve for GCEW

Date Rank Frequency Runoff, mm Nitrate g/ha Dissolved_p

2/21/1997 1 0.016462 63.31199354 881.0208132 142.553319

5/24/1995 2 0.043898 59.65162086 220.1953212 70.25217957

9/23/1993 3 0.071335 59.44457893 51.7507174 89.85975796

5/18/1995 4 0.098771 54.82831095 446.8900301 63.98812325

4/11/1994 5 0.126207 51.84280873 644.8829597 91.32177026

8/24/2000 6 0.153644 46.7014137 178.7126397 65.23956295

6/6/2001 7 0.18108 42.08176259 576.2484652 54.49760983

. . . . .

. . . . .

. . . . .

12/13/2002 3641 99.884767 0 0 0

12/14/2002 3642 99.912204 0 0 0

12/15/2002 3643 99.93964 0 0 0

12/16/2002 3644 99.967076 0 0 0

12/17/2002 3645 99.994513 0 0 0

Flow duration curve for GCEW (1993-2002)

Flow Duration Interval (%)

0 10 20 30 40 50 60 70 80 90 100

Da

ily D

isc

ha

rge

(m

m)

0.0001

0.001

0.01

0.1

1

10

100

1000

High

Flow

Moist

Conditions Mid-range FlowsDry

Conditions Low Flows

Dissolved N load duration Curve for GCEW (1993-2002)


0 10 20 30 40 50 60 70 80 90 100

Da

ily N

itro

ge

n L

oa

d (

g/h

a)

0.0001

0.001

0.01

0.1

1

10

100

1000

10000Daily Load

Median

0.1X Median

10X Median

Point Source Contributions

Dilution Conditions

• Point Source Contributions:

• Flow duration interval > 30%

• Loads above 10X median band.

• Dilution Conditions:

• All daily loads that fall below the 0.1 X median band.

Field1 and GCEW flow duration curves (1993-2002)


0 10 20 30 40 50 60 70 80 90 100

Da

ily D

isc

ha

rge

(m

m)

0.0001

0.001

0.01

0.1

1

10

100

1000

Weir 1

Field 1

Surface Flow

Inter+BaseFlows

Base Flow

% of Total Flow

Flow Field 1 GCEW

Surface97 84

Inter +

Base3 11

Base 0.0 5

Total 100 100

Atrazine Frequency Curves

• The 10X median band did not apply to atrazine load frequency curve,

because almost all the atrazine loads above the 10X band are possibly non-

point source contributions.

• The median load values for F1 are smaller than those for GCEW.


0 10 20 30 40 50 60 70 80 90 100

Da

ily A

tra

zin

e L

oa

d (

g/h

a)

1e-6

1e-5

1e-4

1e-3

1e-2

1e-1

1e+0

1e+1

1e+2

1e+3

Daily Load

Median

0.1X Median

10X Median

Field1 median

GCEW(1993-2002) Field 2 (1997-2001)Field 1 (1993-2002)


0 10 20 30 40 50 60 70 80 90 100

Da

ily A

tra

zin

e L

oa

d (

g/h

a)

1e-6

1e-5

1e-4

1e-3

1e-2

1e-1

1e+0

1e+1

1e+2

1e+3

Daily Load

Median

0.1X Median

10X Median


0 10 20 30 40 50 60 70 80 90 100

Da

ily

Atr

azin

e L

oa

d (

g/h

a)

1e-6

1e-5

1e-4

1e-3

1e-2

1e-1

1e+0

1e+1

1e+2

1e+3

Daily Load

Median

0.1X median

10X Median

Dissolved N Frequency Curves

• The Median values for Field 1 were approx. 10 times lower than those for GCEW.

• Almost all the loads were contributed by non-point source.

GCEW (1993-2002) Field 2 (1997-2001)Field 1 (1993-2002)


0 10 20 30 40 50 60 70 80 90 100

Da

ily N

itro

ge

n L

oa

d (

g/h

a)

0.0001

0.001

0.01

0.1

1

10

100

1000

10000

Daily Load

Median

0.1X Median

10X Median

Field1 Median


0 10 20 30 40 50 60 70 80 90 100

Da

ily N

itro

ge

n L

oa

d (

g/h

a)

0.0001

0.001

0.01

0.1

1

10

100

1000

10000

Daily Load

Median

0.1X Median

10X Median


0 10 20 30 40 50 60 70 80 90 100

Da

ily

Nit

rog

en

Lo

ad

(g

/ha

)

0.0001

0.001

0.01

0.1

1

10

100

1000

10000

Daily Load

Median

0.1X median

10X Median

Dissolved-P Frequency Curves

• Only few loads were suspected to be contributed by point sources.

• Median load values for Field 1 were lower than GCEW.

GCEW (1993-2002) Field 1 (1993-2002) Field 2 (1997-2001)


0 10 20 30 40 50 60 70 80 90 100

Da

ily D

iss

olv

ed

-P L

oa

d (

g/h

a)

0.0001

0.001

0.01

0.1

1

10

100

1000

Daily Load

Median

0.1X Median

10X Median

Field1 Median


0 10 20 30 40 50 60 70 80 90 100

Da

ily D

iss

olv

ed

- P L

oa

d (

g/h

a)

0.0001

0.001

0.01

0.1

1

10

100

1000

Daily Load

Median

0.1X Median

10X Median


0 10 20 30 40 50 60 70 80 90 100

Da

ily D

iss

olv

ed

-P L

oa

d (

g/h

a)

0.0001

0.001

0.01

0.1

1

10

100

1000

Daily Load

Median

0.1X median

10X Median

Sediment Yield Frequency Curves

• Most low concentration events were not analyzed for sediment. In those

cases, a sediment concentration of 34 ppm was assumed.


0 10 20 30 40 50 60 70 80 90 100

Da

ily S

ed

ime

nt

Lo

ad

(g

/ha

)

0.0001

0.001

0.01

0.1

1

10

100

1000

10000

Daily Load

Median

0.1X Median

10X Median

Field 1 Median

GCEW (1993-2002) Field 2 (1997-2001Field 1 (1993-2002)


0 10 20 30 40 50 60 70 80 90 100

Da

ily S

ed

ime

nt

Lo

ad

(g

/ha

)0.0001

0.001

0.01

0.1

1

10

100

1000

10000

Daily Load

Median

0.1X Median

10X Median


0 10 20 30 40 50 60 70 80 90 100

Da

ily

Se

dim

en

t L

oa

d (

g/h

a)

0.001

0.01

0.1

1

10

100

1000

10000

Daily Load

Median

0.1X median

10X Median

Contributions of Surface and Base flows

Good water Creek Experimental Watershed (GCEW)

Flow % Atrazine % Nitrate % Dissolved-P % Sediment

Surface 84 84 87 93

Inter+Base 12 12 10 6

Base 4 4 3 1

Total 100 100 100 100

Field 1

Flow % Atrazine % Nitrate % Dissolved-P % Sediment

Surface 95 96 96 100

Inter 5 4 4 0

Base 0 0.0 0.0 0.0

Total 100 100 100 100

Field 2

Surface 92 96 96 100

Inter 8 4 4 0

Base 0 0 0 0

Total 100 100 100 100

Summary and Conclusion

Watershed and field flow duration curves were consistent Field scale

runoff can be scaled up to watershed scale in this watershed.

Field and watershed flow duration curves provided information to

divide flow into three categories: Surface flow, interflow, and base flow.

Stream constituent loads through these pathways were calculated.

Field scale load duration curves were not a good indicator of what

happened in the watershed:

Different soil vulnerabilities across the watershed.

A range of management in the watershed (planting times, fertilizer and

herbicides application dates).

Load duration curves can be useful to compare between fields.

The upper boundary that distinguishes between non-point and point

sources is likely to be different for different constituents.

Thank you!

linking field and watershed runoff and water quality

Environment