Modelling sediment and phosphorous transport in a … · Department of Bioscience Faculty of...

Department of Bioscience

Faculty of Science and Technology

AARHUS UNIVERSITY

Shenglan Lu

[email protected]

Modelling sediment and phosphorous

transport in a lowland agriculture catchment

1. Department of Bioscience, Aarhus University, Vejlsøvej 25, 8600 Silkeborg, Denmark

2. Department of Hydrology and Hydraulic Engineering, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussel, Belgium

Shenglan Lu1 [email protected]

Joachim Audet1

Hans Thodsen1

Hans Estrup Andersen1

Brian Kronvang1

Ann van Griensven2

with knowledge gained with

field measurements

Department of Bioscience Faculty of Science and Technology AARHUS UNIVERSITY

Shenglan Lu

[email protected]

2/15

Diffuse P loss in Denmark

Lowland catchments

› Soil erosion & Surface

runoff < 10%

› Surface erosion deposit

in field and buffer zone

Important other source

› Bank erosion

› Tile drains

› Ground water

Phosphorus loss

kgP/ha

National scale Severe field scale

Catchment loss

Leaching

Tile drain

Shallow ground water Shallow ground water

Deep ground water

Tile drain

Leaching

Bank erosion

Soil erosion &

surface runoff

Nielsen, K.S., Krongvang, B., Dalsgaard, K., Bay, K. 2004. Fosfer i landbrugsjord og

drænvand. Vand & Jord. 11:3.115-118.


Shenglan Lu

[email protected]

3/15

P loss from bank erosion in Odense › Erosion pin plots: 36 streams

› Erosion & Deposition reading

› Extrapolate plots to all streams

› Calculated bank TP = 25%

Catchment TP

› Sediment TP content

› Bank Sediment: 715 ± 311 mgP/kg

› SS:

› Similar P form -> from bank

sediment

› Higher TP content: fine

particle

R² = 0.1625

0

200

400

600

800

1000

1200

1400

1600

0% 20% 40% 60% 80%

TP c

on

ten

t m

gP/k

g

Coarse sand > 250µm content


Shenglan Lu

[email protected]

4/15

Sediment routing in SWAT: Original (EQN-0) VS Physically based (EQN-1)

› EQN-1: Bank & bed erosion

SS only silt & clay

› TP from Stream

› EQN-0: TP Content * Erosion

› EQN-1: TP Content * Bank Erosion


Shenglan Lu

[email protected]

5/15

Hypothesis

EQN-1 simulate SS and TP in lowland catchments better

than EQN-0

› Daily flow and mineral P (Same EQN-0 & EQN-1)

› Sediment for EQN-0 & EQN-1

› TP for EQN-0 & EQN-1


Shenglan Lu

[email protected]

6/15

Catchment Description

Area 486 km2

Elevation 11 – 124 m

Slope 0.01 – 7.29 m/km

Land use Agriculture: 71%, Forest:15%

Soil Type Sandy Loam: 40%, Sandy Clay: 36%

Climate 1999 - 2010

Precipitation: 850 mm Temperature: 28°C in Aug. -10°C in Jan.

Monitoring Kratholm: Daily flow, time proportion SS, PO4 & TP

!

!

!!

!!!!

!

!

!

!

!!

!

!

!

!

!

!

!

!

#0ST 22.35 Kratholm

0 105 km

#0 kratholm

! banklocation

reach

Land Use

AGRL

PAST

FRST

WETN

WATR

URBN


Shenglan Lu

[email protected]

7/15

Model set up and calibration

› SWAT model

› 29 sub-basin, 429 Hrus, no stream water quality

› Seven 5-year crop rotation, customized crop & manure, tile drainage, point sources, buffer zones, initial P in soil, low MUSLE erosion

› EQN-0 VS EQN-1: same catchment, different stream › EQN-1: measured bulk density, D50, TP content

› Calibration

› Daily flow and annual solute P › Same for EQN-0 & EQN-1

› Daily SS

› Annual particulate P (PP)

Warm up Calibration Validation

Daily Flow 1989-1998 1999-2003 2004-2010

Solute P

Daily SS

PP

1989-1998 1999-2004 2005-2010


Shenglan Lu

[email protected]

8/15

Flow

0

5

10

15

20

25

30

35

40

45

50

Dai

ly s

tre

am f

low

m3/s

Model

Observe

Validation Calibration

Base flow 45% Tile

drains 37%

Surface runoff 15%

Lateral flow 3%

NSE 0.82

PBIAS -0.5%

NSE 0.79

PBIAS 5%

0

50

100

150

200

250

300

350

400

450

500

1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010

Wa

ter

Yie

ld m

m/y

r

Observe

Model


Shenglan Lu

[email protected]

9/15

PO4

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010

PO

4 k

gP

/ha

Estimate

Model

0

100

200

300

400

500

PO

4 k

g/d

ay

Model

Observe


NSE -0.11

PBIAS 47%

NSE -0.26

PBIAS 43%

Surface runoff 63%

Base flow 27%

Point source 10%

Base flow 45% Tile

drains 37%

Surface runoff 15%

PO4 Flow


Shenglan Lu

[email protected]

10/15

SS: EQN-0 VS EQN-1

0

20

40

60

80

100

120

140

SS m

g/l

EQN-1EQN-0Observe


EQN-0 EQN-1

NSE 0.21 0.23

PBIAS 15% 10%

EQN-0 EQN-1

NSE 0.13 0.14

PBIAS 29% 27%

0

500

1000

1500

2000

2500

3000

3500

4000

4500

1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010

SS

lo

ad

to

n/y

r

Estimate

EQN-0

EQN-1

-500

0

500

1000

1500

2000

2500

EQN-0 EQN-1

Ave

rag

e a

nn

ua

l S

S lo

ad

to

n/y

r

Surface Erosion

Bed erosion

Bank erosion

Deposision


Shenglan Lu

[email protected]

11/15

!.

!.

!.

!.

!.

!.

!.

!.

!.

!.

!.

!.

!.

!.

!.!.

!.

!.

!.

!.

!.

!.

!.

!.

!.

!.

!.

!.

!.

!.

!.!.

!.

!.

!.

0 105 km

Bank Erosion

› SWAT: some

distribution

› Bank erosion:

site specific

Obs Erosion mm

!. -155.160920 - -87.962500

!. -87.962499 - -36.028986

!. -36.028985 - -14.888889

!. -14.888888 - 0.000000

!. 0.000001 - 11.839080

!. 11.839081 - 40.033333

!. 40.033334 - 97.786667

EQN-1 erosion ton

-1375.120000 - -1329.690000

-1329.689999 - -587.260000

-587.259999 - -164.100000

-164.099999 - 0.000000

0.000001 - 185.322100

185.322101 - 519.086000

519.086001 - 1504.887549


Shenglan Lu

[email protected]

12/15

PP: EQN-0 vs EQN-1

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

1999 200020012002 2003200420052006 200720082009 2010

PP

kg

P/h

a

Estimate

EQN-0

EQN-1

0

500

1000

1500

2000

2500

3000

3500

4000

4500

199920002001200220032004200520062007200820092010

SS

lo

ad

to

n/y

r

Estimate

EQN-0

EQN-1

-4000

-2000

0

2000

4000

6000

8000

10000

Bank erosion Deposision Sediment Out

Ave

rag

e a

nn

ua

l s

ed

ime

nt

bu

dg

et

ton

/yr

EQN-1 Silt&Clay (TSS)

EQN-1 Other particles

0.000

0.050

0.100

0.150

0.200

0.250

0.300

EQN-0 EQN-1

Ave

rag

e a

nn

ua

l P

P k

gP

/ha

Surface runoff

Point Source

Bank erosion


Shenglan Lu

[email protected]

13/15

TP: EQN-0 vs EQN-1

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010

TP

kg

P/h

a

Estimate

EQN-0

EQN-1

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

1999200020012002 200320042005 2006200720082009 2010

PP

kg

P/h

a

Estimate

EQN-0

EQN-1

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010

PO

4 k

gP

/ha

Estimate

Model

0.000

0.050

0.100

0.150

0.200

0.250

0.300

0.350

0.400

0.450

0.500

EQN-0 EQN-1 Estimate

Ave

rag

e a

nn

ua

l T

P k

gP

/ha

Bank erosionSurface runoffBase flowPoint source


Shenglan Lu

[email protected]

14/15

0

100

200

300

400

500

600

700

800

900

1000

Oct

-99

Dec

-99

Feb

-00

Ap

r-0

0

Jun

-00

Au

g-0

0

Oct

-00

Dec

-00

Feb

-01

Ap

r-0

1

Jun

-01

Au

g-0

1

Oct

-01

Dec

-01

Feb

-02

Ap

r-0

2

Jun

-02

Au

g-0

2

Oct

-02

Dec

-02

Feb

-03

Ap

r-0

3

Jun

-03

Au

g-0

3

Oct

-03

Dec

-03

Feb

-04

Ap

r-0

4

Jun

-04

Au

g-0

4

TP k

gP/d

ay

EQN-1

EQN-0

Observe

Daily TP: EQN-0 VS EQN-1

EQN-1:

› Higher peaks

› Follow recession

EQN-0 EQN-1

NSE 0.15 0.63

PBIAS 61.9% 25.3%


Shenglan Lu

[email protected]

15/15

CONCLUSION

› Daily flow: very good in lowland catchment

› PO4 load: lack input from tile drains

› TSS: EQN-1 higher peaks & lower low concentrations

than EQN-0

› TP: EQN-1 better than EQN-0 in lowland catchments

Thanks for your attention!

Questions?


Shenglan Lu

[email protected]

16/15

Daily SS: EQN-0 VS EQN-1

0

10

20

30

40

50

60

70

80

Oct

-01

Dec

-01

Feb

-02

Ap

r-0

2

Jun

-02

Au

g-0

2

Oct

-02

Dec

-02

Feb

-03

Ap

r-0

3

Jun

-03

Au

g-0

3

Oct

-03

Dec

-03

Feb

-04

Ap

r-0

4

Jun

-04

Au

g-0

4

SS m

g/l

EQN-0EQN-1Observe

0

20

40

60

80

100

120

140

Oct

-06

Dec

-06

Feb

-07

Ap

r-0

7

Jun

-07

Au

g-0

7

Oct

-07

Dec

-07

Feb

-08

Ap

r-0

8

Jun

-08

Au

g-0

8

Oct

-08

Dec

-08

Feb

-09

Ap

r-0

9

Jun

-09

Au

g-0

9

SS m

g/l

EQN-0EQN-1Observe

Equally bad

EQN-1:

› Higher peaks

› Lower low

concentration

EQN-0 EQN-1

NSE 0.21 0.23

PBIAS 15% 10%

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Modelling sediment and phosphorous transport in a … · Department of Bioscience Faculty of...

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