Impact of current conservation practices on sediment load reduction in the Danube River Basin Olga Vigiak, Anna Malagó, Fayçal Bouraoui, Marco Pastori, Pasquale Borrelli, Alberto Pistocchi www.jrc.ec.europa.eu

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Context of the research •

Water Framework Directive (WFD) requires freshwater bodies achieving good ecological status by 2015

•

Conservation practices (Best Management Practices – BMPs) are at the core of strategies to achieve the WFD targets

•

But what has been the impact of BMPs on pollution (e.g. sediments) so far?

•

Objective of the study was to assess the impact of conservation practices already implemented on sediment reduction in a large European

river basin (the Danube)

Workflow BMPs estimation

SWAT

BMP effectiveness

1 July 2015

• Spatial distribution • SWAT implementation • Model calibration • Current BMPs, 1995-2004 • SWAT run without each BMPS • Ratio of sediment loads per regions

Best Management Practices HRU

• Cover crops, • Residue management, • Conservation tillage, • Terracing/contouring

HRU border

• Riparian land (filter strips)

Instream

1 July 2015

• Streambank protection • Reservoirs/locks

SWAT2015 Conference, Pula, 24-26 Jun 2015

The Danube Basin ~2700 km, 834000 km2 area, 19 Countries (4663 subbasins of 172 km2 average)

Farming system BMPs Eurostat 2010 data (Nuts2)

Cover crops: 15013 km2 (4%) of arable land Conservation (minimum or no till) tillage: 77469 km2 (20%) of arable land Residue management: 18400 km2 (5%) of arable land Terracing: fraction of holdings with stonewalls ~ proxy for terrace density; ranged 0-25% (weighted mean 1.3%) 1 July 2015

SWAT2015 Conference, Pula, 24-26 Jun 2015

SWAT implementation BMP

Approach

Applied to

Cover Crop

One year rotation (Arabi et al. 2008)

Annual crops

Conservation tillage

Minimum tillage (adapted from Ullrich and Volk 2009, Lam et al., 2011)

Annual crops

Residue Management

Change Harvest&Kill into Kill

Summer cereals

Terracing

Manual USLE P/slope look-up * changes in LS factor * fraction of terraced land

pastures and permanent crops, Slopes 5-60%

1 July 2015

SWAT2015 Conference, Pula, 24-26 Jun 2015

Overview of farming system BMPs Current farming system BMPs cover

471 Hrus - 23% of arable HRUs; 28% of arable land area Terracing USLE P correction ranged 0.77- 0.99 However, USLE P < 0.97 only in 10% of these HRUs

1 July 2015

SWAT2015 Conference, Pula, 24-26 Jun 2015

Riparian land map Pan-European map of riparian vegetation types at 25m resolution (Clerici et al. 2013; Weissteiner et al. 2013) + CORINE wetlands

Modelled as filter strips VSFRATIO ~ area of subbasin/area of riparian zone in the subbasin (limited in the range 10-200) No data area: attributed characteristics of neighboring regions Applied to pastures or cropland hrus

SWAT implementation (ops table) 600 0 200

original = from Clerici et al. map (2152 hrus)

Frequency

original

0

50

100

150

200

150

200

VFS ratio in riparian map

600 0 200

final = including the nodata region (2815 hrus, 54%)

Frequency

final

0

50

100 VFS ratio in the Danube

Operation

Parameters

SWAT2012 (filter.f)

FILTER_I (VSFI)=

FILTER_RATIO (VSFRATIO) =

FILTER_CON (VSFCON):

FILTER_CH (VFSCH):

MNG_OP=4

1

10-200

0.25

0.10

Riparian land in the Danube (cropland and pastures)

In-stream (streambank & reservoirs/locks) Clerici et al. 2013 riparian map (25m) used for estimating vegetation along the main stream (CH_COV; note: CH_EQN=3)

No data: values assigned depending on land use, slope and drainage area Major reservoirs and hydropower plant locks (114) included 1 July 2015

SWAT2015 Conference, Pula, 24-26 Jun 2015

30 25 20

Predicted

0

5

10

15

20 15 0

5

10

TSS (mg/L)

25

30

SWAT sediments (uncalibrated)

35

60000662 TSS (mg/L)

35

Morava - Devin

1996

1998

2000

2002

2004

0

5

10

15

Year

Danube - DELTA

30

35

30 Predicted

2000

40

1998

2002

2004

0

Year

10

20

30

40

observed

0

20

40

1996

20

20 0

0

10

TSS (mg/L)

10

20

120 100 80 60

60

Predicted

80

100

120

30

140

140

40

60000212 TSS (mg/L)

0

TSS (mg/L)

25

60000122 TSS (mg/L)

40

Inn - Passau Ingling

20

observed

1996

1998

2000 Year

1 July 2015

2002

2004

0

20

40

60

80

100

120

140

observed

SWAT2015 Conference, Pula, 24-26 Jun 2015

SWAT sediments (uncalibrated)

Predicted

1998

2000

2002

2004

0

10

20

30

40

10

observed

0

10

20 0

0

10

TSS (mg/L)

20 10

40 20

Predicted

30

40 30 20

1996

Year

0

TSS (mg/L)

30

60000777 TSS (mg/L) 30

Donau - Esztergom

40

60000122 TSS (mg/L)

40

Danube - DELTA

1996

1998

2000 Year

1 July 2015

2002

2004

0

10

20

30

40

observed

SWAT2015 Conference, Pula, 24-26 Jun 2015

Tisa - Titel

60000073 TSS (mg/L)

40 30 20

Predicted

0

10

20 0

10

TSS (mg/L)

30

40

SWAT sediments (uncalibrated)

2001

2002

2003

2004

2005

0

10

Year Danube - DELTA

40 30 Predicted

0

10

20

30 20

40

TSS (mg/L)

30

0

1998

2000

2002

2004

0

10

20

30

40

observed

0

10

Year

10

40

20

Predicted

10

40 30 20

1996

0

TSS (mg/L)

30

observed 60000122 TSS (mg/L)

60000122 TSS (mg/L)

40

Danube - DELTA

20

1996

1998

2000 Year

1 July 2015

2002

2004

0

10

20

30

40

observed

SWAT2015 Conference, Pula, 24-26 Jun 2015

Results example: (i) impact of riparian land at HRU scale HRU SY (t/ha)

100 0

0.0

0.2

50

0.4

Current

0.6

0.8

150

1.0

Riparian efficiency - HRU SY

0

50

100

150

200

250

no riparian land

1 July 2015

SWAT2015 Conference, Pula, 24-26 Jun 2015

(ii) impact at reach scale 1.0 0.5 0.0 -0.5 -1.0 -1.5 -2.0

Efficiency riparian land

-1.5 -2.0

-1.0

-0.5

0.0

0.5

1.0

Efficiency of Riparian land in all reaches

0.00

0.02

0.04

0.06

0.08

0.10

Riparial land fraction

1 July 2015

SWAT2015 Conference, Pula, 24-26 Jun 2015

(iii) Impact at regional scale 250.00

No Riparian land

Current

Efficiency of Riparian land in Danube regions

0.2

150.00

100.00

0.1

50.00

0.0

Efficiency SSY

0.3

0.4

Specific Sedimen Yield (t/km2)

200.00

0.00

1 July 2015

SWAT2015 Conference, Pula, 24-26 Jun 2015

Discussion -

Potential errors in spatial attributions of BMPs

-

Literature reports different implementation of BMPs in SWAT (e.g. conservation tillage) -> impact on BMPs ‘effectiveness’

-

Wetlands: currently SWAT only consider impact on the subbasin, cannot consider upstream reaches load (longitudinal connectivity)

-

Careful calibration (water and sediments) is needed to achieve correct representation of sediment generated in land vs stream phase processes

1 July 2015

SWAT2015 Conference, Pula, 24-26 Jun 2015

Conclusions & outlook Good general performance of SWAT for suspended sediment modelling

even in uncalibrated conditions (but careful set-up) This study will help revealing the real impact of BMPs on sediment (and in

the future, on nutrients) at several scales (from local to regional) The BMPs rules & calibrated SWAT model can be used for scenario analysis Further contact: [email protected]

Selected references Arabi M, Frankenberger JR, Engel BA, Arnold JG. 2008. Representation of agricultural conservation practices with SWAT. Hydrological Processes 22, 3042-3055. Doi: 10.1002/hyp.6890 Clerici N Weissteiner CJ, Paracchini ML, Strobl P 2011. Riparian zones: where green and blue networks meet. Pan-European zonation modleling based on remote sensing and GIS. JRC Scientific and technical reports EUR24774EN, Joint Research Centre – Institute for Environment and Sustainability, Luxenburg, 60pp doi: 10.2788/80271 ISBN 978-92-79-19799-4. Clerici N, Weissteiner C J, Paracchini ML, Boschetti L, Baraldi A, Storbl P. 2013. Pan-European distribution modleling of stream riparian zones based on multi-source Erath Observation data. Ecological Indicators 24, 211-223 Hatterman FF, Krysanova V, Habeck A, Bronstert A. 2006. Integrating wetlands and riparian zones in river basin modelling. Ecological Modelling 199, 379-392. Lam QD, Schmalz B, Fohrer N. 2011. The impact of agricultural Best Management Practices on water quality in a North German lowland catchment. Environmental Monitoring Assessment 183, 351-379. Doi: 10.1007/s10661-011-1926-9. Ullrich A, Volk M. 2009. Application of the Soil and Water Assessment Tool (SWAT) to predict the impact of alternative management practices on water quality and quantity. Agricultural Water Management 96, 1207-1217. Weissteiner CJ, Bouraoui F, Aloe A. 2013. reduction of nitrogen and phosphorus loads to European rivers by riparian buffer zones. Knowledge and management of aquatic ecosystems 408: 8