Fate & Transport Modeling of the herbicides

M e ta za c h l o r & F l u fe n a c e t

using SWAT

A. Dietrich, N. Fohrer, F. Schulz 2011 International SWAT Conference Toledo --- June 15, 2011

Department of Hydrology and Water Resources Management - Fohrer et al. -2-

Project motivation

• Good ecological status as goal of EG-WFD (2000)

• pesticide emission from agricultural fields

• 3 year monitoring project to determine main entry pathways

Development of management options to reduce herbicide loads

(State Agency for Agriculture,

Environment and Rural Areas

(LLUR))

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Study Area – Rural lowland catchment Kielstau

Low hydraulic gradients, near-surface groundwater

• 2 % Slope on average

High potential for water retention

• Riparian wetlands and interaction between

groundwater & surface water

• Depression areas

• 1 Lake

Anthropogenic influences

• Fertilizer and pesticides application

• 5 sewage treatment plants

• River regulations

• Drainages

27-79 m ASL

56 % arable land 30 % grassland / fallow 9 % forest

50 % Stagnic Luvisols 38 % drained area (FOHRER ET AL. 2007)

Area: 50 km²

Mean T: 8.2 °C

PCP: 870 mm/a

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Setup of SWAT 2009

stream

gauge

Subbasins: 17 HRU: 938 Thresholds: (0% land use, 20 % soil, 20 % slope)

Topography (DEM 5x5 m)

Land use (mapping in 2008)

Soils (1:200.000)

Climate (1993 – 2009)

Precipitation, Wind, Humidity, Temperature

Calculating ALPHA_BF (Baseflow Program; ARNOLD ET AL. 1995)

Initial Setup

LVERMA (2005)

GOLON (2009)

BGR (1999)

DWD (2010)

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Input Input Drain

Input Depression

Drain input: - Artificial drained areas calculated after FOHRER ET AL. (2007) - Via soil properties (Ksat, AWC)

Initial Setup

KIESEL ET AL. (2010)

Depression input: - After the approach by KIESEL ET AL. (2010) - Input as Wetlands

Digitalised drained area

Simulated drained area (FOHRER ET AL. 2007)

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Other Rape

Winter cereals

Input Initial Setup

RAPE WWHT WBAR

Maize

RAPE WWHT WWHT

POTA WWHT WBAR

BARL Maize

Land use (mapping in 2008, GOLON 2009)

Input typical Crop Rotations Input Drain

Input Depression

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Input Initial Setup

Input typical Crop Rotations

Input Pesticides Input Drain

Input Depression

• Measurements at the outlet by ULRICH 2010, LLUR 2010

MET: 2008 (09/01-11/30/2008)

FLU: 2009 (09/24-12/05/2009)

• Farmer interviews

- application date

- application rate

- MET: 49 % of rape fields

- FLU: 44 % of winter cereal fields

1998 2003 2009 Discharge Metazachlor

Flufenacet

Warm-up Calibration period Validation period

2006

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Input Initial Setup

Input typical Crop Rotations

Input Pesticides Input Drain

Input Depression

Metazachlor in RAPE both not implemented in SWAT so far Flufenacet in WWHT, WBAR

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discharge simulations

C a l i b r a t i o n

V a l i d a t i o n M e t a z a c h l o r p e r i o d F l u f e n a c e t p e r i o d

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Simulation of Metazachlor concentrations (RAPE)

concentration

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Flufenacet , multiple application (WWHT,WBAR)

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Effect of application date

F l u f e n a c e t o n l y a p p l i e d o n W B A R

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Effect of Flufenacet properties KOC = Soil adsorbtion coefficient HLIFE_S = Half-life (soil)

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Interim conclusion – major obstacles: data

• Information deficits on

– crop rotation (which winter cereal?)

– application location within the catchment ?

• Multiple application periods

• Rel. short measurement periods

• High variation of properties of pesticides

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• Simulation results depend mainly

– on flow parameters

• dynamics of curve

• high accuracy necessary

– application date (initial peak)

– Pesticide properties

magnitude of conc.

but NOT shape of curve

Interim conclusion – simulation

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T h a n k y o u f o r y o u r a t t e n t i o n .

Kielstau (Springer, 2007)

MSc. Antje Dietrich adietrich@hydrology.uni-kiel.de