Brian Kronvang EEA Workshop 11-12 September 2008 U N I V E R S I T Y O F A A R H U S Danish...

U N I V E R S I T Y O F A A R H U S

Danish Environmental Research InstituteDepartment of Freshwater Ecology

Brian KronvangEEA Workshop 11-12 September

2008

Brian KronvangNational Environmental Research Institute, Dept. Freshwater Ecology, University of Aarhus, Silkeborg, [email protected]

(WP5)NutrientRetention

in Catchments&

Applicability ofQuatification

Tools onEuropean

Catchments

Ensemble modelling of diffuse nutrient loads and sources in EUROHARP catchments:Uncertainty in applying different models and the problem with retention




2008

No ‘European best model’ was nominated by the EUROHARP project (2001-2006) but we learned a lot about models and the EUROHARP Toolbox is a potential ‘money saver tool’ for catchment managers




2008

Conclusions and recommendations regarding nutrient emissions Net nutrient loads should always be quantified using

monitoring/modelled results – the net load is the most accurate estimate as shown in EH.

Gross nutrient emissions from background or non-anthropogenic sources should be quantified independently using monitoring data or models.

Nutrient retention in surface waters should be quantified independently using model estimates at water body or river basin scale (EUROHARP NUTRET tool).

EUROHARP has shown that ensemble modelling is a possible way forward to ensure that an estimate of the uncertainty involved in especially nutrient load partitioning can be given.

Application of more than one model will be useful in the future emission reportings as e.g. one simple pan-European method (statistical model), one load apportionment method and one country specific method (source oriented).




2008

Continued Agricultural emissions should always be reported using three

indicators:1. Nutrient surplus2. Leaching from root zone (1 m) (gross emission to groundwater

and surface water).3. Gross emission to surface water – edge of surface waters HYDROLOGICAL DATA IS CRUCIAL BEFORE EVERYTHING ELSE. OSPAR HARP-NUT has developed several guidelines concerning

nutrient losses also an updated guideline 6 on diffuse nutrient losses and guideline 9 on nutrient retention both based on EUROHARP results is to be prepared by Denmark.

EUROHARP has created a tool box to assist catchment managers in chosing the best model(s) for a given river basin.




2008

Nutrients Point

Sources

Nutrient Retention

NutrientsDiffuse Sources

Ecology of water body types

Nutrients ReferenceConditions

WFD sets new standards and requirements for calculation of nutrient sources, emissions and retention in catchments with the purpose of achieving a concentration in surface waters below the level required for obtaining a good ecological quality




2008

Background concentrations of nitrate-N in Danish surface waters – large regional differences




2008

Nutrient losses from fields to surface waters – the problem of retention

Surplus

Leaching

Root

Zone

Surface runoff

Subsurface emission

subsurface retention (b)

surface water retention

(c)

Point sources, background, atm. deposition

wetland retention (d)

Catchment export

Total retention = a+b+c+d+e

root zone retention (a)

buffer zone retention (e)




2008

Estimated Nitrogen retention in groundwater and surface waters for different Danish catchments used for WFD River Basin

Management plans




2008

Daily simulations of flow

and solute concentrations

Annual predictions based on

export coefficient approach

Process oriented(deterministic)

Data oriented

(empirical)

High

Low

Level of complexity

Model typeMethods differ profoundly in their complexity, level of process representation and data requirements

SA NOPOLU REALTA

NL-CAT SWAT

NLES-CAT MONERIS EVENFLOWTRK

EUROHARP model tools




2008

Nutrient emissions – the EUROHARP definitions




2008

Location of the EUROHARP river catchments and diffuse gross N-losses to surface waters




2008

Large differences in the bias involved when modelling net N export from European catchments




2008

• The mean deviation between the P-loads calculated by linear interpolation or by the OSPAR method is ~22%.

0.0001

0.0010

0.0100

0.1000

1.0000

10.0000

0.0001 0.0010 0.0100 0.1000 1.0000 10.0000

specific P load linear interpolation (kg/(ha·a))

spe

cific

P lo

ad

OS

PA

R (

kg/(

ha

·a))

• More than 1/3 of the deviation between the model results for P-loads are due the uncer-tainty of the “observed” P-load

0.0001

0.0010

0.0100

0.1000

1.0000

10.0000

0.0001 0.0010 0.0100 0.1000 1.0000 10.0000

specific P load linear interpolation (kg/(ha·a))

spe

cific

P lo

ad

OS

PA

R (

kg/(

ha

·a))

• Higher deviations occur also for Southern European catchments.

• Precision of loads depends on substance, observation frequency and catchment size.




2008




2008

Mean deviation when modelling nitrogen (N=66) and phosphorus (N=50) in 17 EUROHARP catchments

Mean deviation N P

Net load (export from catchment): 27% 41%

Gross loss from agricultural land: 37% 67%

Gross loss from other diffuse sources:67% 75%




2008

Nutrient retention in surface waters was the factor experiencing the largest variation between models.




2008

EUROHARP Nutrient Retention Software - NUTRET

Offer nutrient retention calculations in different Tiers

Tier 1: Simple - Tier 5: Advanced




2008

In future more emphasis has to be drawn on delivering nutrient modelling results from modellers to managers with some measure of the uncertainty involved

0

20

40

60

80

100

Catchments

Spe

cific

N lo

ss fr

om

agric

ultu

ral l

and

(kg

N/h

a)




2008

General information about the EUROHARP project, partners and modelled European catchments

Tools and models used in project, search in model capabilities, add new tools

Educational pages related to diffuse pollution from European catchments, guidelines

Policy instruments; European and international, relating to diffuse pollution

Water Framework

Directive

Brian Kronvang EEA Workshop 11-12 September 2008 U N I V E R S I T Y O F A A R H U S Danish...

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