UFZ UMWELTFORSCHUNGSZENTRUM LEIPZIG-HALLE GmbH 18 - 22 October 2004 in Leipzig, Germany at the UFZ...

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18 - 22 October 2004 in Leipzig, Germanyat the UFZ Centre for Environmental Research

11th Magdeburg Seminar on Waters in Central and Eastern Europe

Uncertainties in the mesoscale modelling of water and nitrogen fluxes

The project: “Water and nutrient fluxes in the loess region in the Elbe catchment as a basis for sustainable land use”

German Ministry of Education and Research:

“Ecological research in the riverine landscape of the River Elbe”(No. 0339586)

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Study area:

- 2700 km²

- loess region

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Problem

0

1

2

3

4

5

6

7

8

1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000

mg/l

0

20

40

60

80

100

120m3/s

total N

flow m3/s

Environmental quality target

flow rate (m³/s)

Bad Düben river gauge

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Aim

• To find a way of quantifying nitrogen inputs

- via their discharge pathways

- 2700 km² mesoscale investigation

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receiving water

grou

ndw

ater

flow

tile

drai

nage

dire

ctru

noff

grasslandarable land unsealedurban areas woodland water

point sourcesdiffuse sources

atmospheric depositionsurplus on agriculturalnitrogen balance domestic/industrial waste water

calc

ulat

ion

of d

isch

arge

estim

atio

nof

dis

char

ge

sew

age

syst

em

dire

ctin

dust

riald

isch

arge

rs

dire

ctin

put

grou

ndw

ater

flow

(diff

use)

sew

age

plan

ts

receiving water

grou

ndw

ater

flow

tile

drai

nage

dire

ctru

noff

grasslandarable land unsealedurban areas woodland water

point sourcesdiffuse sources

atmospheric depositionsurplus on agriculturalnitrogen balance domestic/industrial waste water

calc

ulat

ion

of d

isch

arge

estim

atio

nof

dis

char

ge

sew

age

syst

em

dire

ctin

dust

riald

isch

arge

rs

dire

ctin

put

grou

ndw

ater

flow

(diff

use)

sew

age

plan

ts

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Aims

• To find a way of quantifying nitrogen inputs

- via their discharge pathways

- mesoscale investigation

• To quantify the error rate of the results (input data)

sensitivity analyses:

- total runoff

- nitrogen losses

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ABIMOClimate values

precipitation

Po = 1.09 * P1 max. evapo-transpiration acc. to TURC [36] ET1.1*TURC

Land use

Agriculture Forestry Non-vegetated land Sealed area

Soil type (effective field capacity)

Sand Silt Loam Clay Peat

Groundwater level

Irrigation

Mean effective root depth TW

Rise elevation TA = TG - TW

Capillary rise rate CR

TG B

Establishment of efficiency parameters xP KR BETo

TURC

11. *

n = 0.11 nB = 1.5 * n

BAGROV relation

y = ETa / ET1.1*TURC

Actual evaporation ETa = y * ET1.1*TURC

Total flow R and groundwater recharge rate GWR R = Po - ETa

Po ET1.1*TURC

nETpETa

dPdETa

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Sensitive analysis 17% reduction in mean annual precipitation values(error calculated by Wendland 1999)

Derivation of the effective field capacity via Method B(derivation through soil profiles)

precipitation –7%

precipitation +7%

Sensitive analysis 2




(error calculated by Wendland 1999)7% increase in mean annual precipitation values

Derivation of the effective field capacity via Method B

Derivation of the effective field capacity via Method B

Sensitivity analyses

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Alternative calculations Derivation via Method A

(substrate)Derivation via Method B

(soil profiles)effective field capacity (mm)

–

–

–

–

–

–

–

–

Non-agriculturalareasNatural regions

Rivers

loess lessivé

loess pseudogley

mountainous soils

glacial sand

sandy loess

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Vergleich der Grundwasserneubildung nach unterschiedlicher Herleitung der nFk-Werte

0

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200

300

400

500

600

700

0 100 200 300 400 500 600 700

Methode A (nach Bodenformen)

Met

hode

B (n

ach

Subs

trat

)

Methode B (nach Bodenformen)Methode A (nach Substrat)

Method B

Method A

mmmm

mm


Total runoff

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Max Min Range

Reference calculation 224 707 -98 805 126


181 648 -141 789 124

Variante 2(precipitation +7%) 269 767 -56 823 129

Variante 3

effective field capacity acc. to Method B 230 707 -98 805 127

Variante 4effective field capacity acc. to Method Bprecipitation +7%)

187 648 -141 789 125Variante 5

effective field capacity acc. to Method Bprecipitation –7%)

274 767 -56 823 130





Mean Standard deviation

(precipitation –7%)

Max Min Range

Reference calculation 224 707 -98 805 126


181 648 -141 789 124

Variante 2(precipitation +7%) 269 767 -56 823 129

Variante 3

effective field capacity acc. to Method B 230 707 -98 805 127

Variante 4effective field capacity acc. to Method Bprecipitation +7%)

187 648 -141 789 125Variante 5

effective field capacity acc. to Method Bprecipitation –7%)

274 767 -56 823 130





Mean Standard deviation

(precipitation –7%)

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Conclusion

• Changing effective field capacity raised total runoff values by 5%

• The changes in annual precipitation caused a nearly 19% decrease and a 20% increase in total runoff values

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Calculation of N losses

Nl = (NBAL – NDEN) * EF

Nl = Potential annual N load (kg N /ha) NBAL = Agricultural nitrogen balance (kg N/ha) NDEN = Denitrification (kg N/ha) EF = Exchange factor

Ex = (GWR / FCrs) * 100

Ex = Exchange frequency of soil water (%) GWR = Groundwater recharge rate (mm) FCrs = Field capacity in rooted soil (mm)

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Sensitive analysis 2 7% reduction in mean annual precipitation values(error calculated by Wendland 1999)


Sensitive analysis 4 Increase in the agricultural nitrogen balance of 30 kg/ha*a,consideration of the atmospheric deposition, derivation of effective field capacity acc. to Method A


Derivation of field capacity acc. to Method B

(error calculated by Wendland 1999) 7% increase in mean annual precipitation values

Increase in the agricultural nitrogen balance of 30 kg/ha*a,consideration of the atmospheric deposition, derivation of effective field capacity acc. to Method B

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Sensitive analysis 4 Increase in the agricultural nitrogen balance of 30 kg/ha*a,consideration of the atmogen deposition, derivation of effective field capacity acc. to Method A




Increase in the agricultural nitrogen balance of 30 kg/ha*a,consideration of the atmogen deposition, derivation of effective field capacity acc. to Method B

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gaseous deposition: e.g. NH3, NO, NO2, HNO3

total N-deposition

dry deposition

wet depositiongaseous

deposition

soilvegetation bulk-deposition

soliddeposition

Calculation of the total N deposition

Mehlert 1996

Integral total nitrogen method (Weigel et al. 2001)

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Sensitive analysis 4 Increase in the agricultural nitrogen balance of 30 kg/ha*a,consideration of the atmogen deposition, derivation of effective field capacity acc. to Method A




Increase in the agricultural nitrogen balance of 30 kg/ha*a,consideration of the atmogen deposition, derivation of effective field capacity acc. to Method B

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Langweiler einfügen

Saldo + 30 / nFK M2SSaldo +30/FK MBSaldo + 30 / nFK M1Saldo +30/FK MANiederschlag + 7Niederschlag -7Niederschlag - 7Niederschlag -70

2000

4000

6000

8000

10000

12000

14000

16000

nFK M1 nFK M2

t/a

FK MA FK MBAC1 AC2 AC3 AC4 AC5 reference calculation

4000

2000

14000

16000

12000

10000

8000

6000

0

M g

SA 1 SA 2 SA 3 SA 4 SA 5

Mg

FRACHT_T90FK MA

0

1000

2000

3000

4000

5000

6000

7000

8000

FRACHT_F90 Summe von T90 - 7_HA Summe von T90+7_HAT90_p30_ha

Summe von FRACHTF90_p30_haFK MB Niederschlag -7 Niederschlag +7 Saldo +30/FK MA Saldo +30/FK MB

t/a

AC1 AC2 AC3 AC4 AC5 reference calculation

8000

7000

6000

5000

4000

3000

2000

1000

0

Mg

SA1 SA2 SA3 SA4 SA5 calculationreference

Mg


1986–89 1997–99

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ConclusionsCalculation of total runoff:

Changing effective field capacity causes a 5% change in the results, ann. precipitation approx. 20%.

Calculation of N losses: Changing soil and climate parameters change the

results by up to 10%. The main uncertainty: considering total atmogen

deposition. - high uncertainty of the input data - high sensitivity for the results Further investigations of the total atmogen deposition in different crops and different natural regions are necessary to improve the uncertainties of the calculation of N losses.

UFZ UMWELTFORSCHUNGSZENTRUM LEIPZIG-HALLE GmbH 18 - 22 October 2004 in Leipzig, Germany at the UFZ...

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Transcript of UFZ UMWELTFORSCHUNGSZENTRUM LEIPZIG-HALLE GmbH 18 - 22 October 2004 in Leipzig, Germany at the UFZ...