Surface water diffuse pollution by PPP: focus on runoff & erosion

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Surface water diffuse pollution by

PPP: focus on runoff & erosion

B. Bah, L. Vandendael, R. Oger, A. Degré TOPP

S-PRO W AD IS St ak eh o ld er w o rk sh o p 1 04/04/2012

Runoff and erosion risks

Erosion

Potential effect on river quality and damages to settelment

Runoff erosion splash

(2)

Some illustrations

of the problems

3

The causes : rain, soil, slope, slope lenght, landuse

(soil cover and watershed organisation)

Modèle EPICgrid : Evolution des précipitations annuelles (1971-2005) dans le sous-bassin hydrographique de la Senne

y = 4.2373x - 7594.2 400 500 600 700 800 900 1000 1100 1200 1300 19711972197319741975197619771978197919801981198219831984198519861987198819891990199119921993199419951996199719981999200020012002200320042005 P ré c ipita tions a nnuel le s (mm/ a n)

Précipitations annuelles (mm/an) Linéaire (Précipitations annuelles (mm/an))

Source : IRM et SETHY

An n u al r ai n fal l ( mm/ an ) 4

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The solutions : in-field AND watershed management

Better transfer

Outlet management Less runoff /soil detachment

 Toolbox of mitigation measures 5

Mitigation measures

Watershed management Vegetative buffers Grass strips Edge of field Soil tillage

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Mitigation measures (2)

7 Vegetated filter strip

Vegetated waterways

Soil cover

In field retention

Mid- and downhill protection

8 Temporary dam

Dike and temporary retention zone

Channel restriction and temporary retention zone

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Which measure ??

Where??

When??

9 TOPP S-PRO W AD IS St ak eh o ld er w o rk sh o p 04/04/2012

The « ERRUISSOL » Project

• A focus on the very beginning of runoff and

erosion phenomenon for risk mapping

• ERosion

• Diffuse erosion risk mapping

• Slope, Rain erosivity, Soil erodibility mapping

• Actual land use mapping

• « RUISsellement »  Runoff

• Runoff production mapping

• Runoff concentration mapping

• « SOL »  Soil

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Diffuse erosion risk map

Calculated for each 10 x10m pixel

A = R.K.C.LS.P

Soil losses

[t/ha.an]

Fixed at a reference level admitted : 10 t/ha.an

Rain erosivity

On the basis of 30 years of daily observation and previous research aiming at R factor adaptation to the Walloon

context

Soil erodibility

Systematic use of Wishmeier abacus and statistical analysis

Crop factor

Fixed for 3 land uses : - Row crop - Other crops

- Grassland

Slope and slope length

Slope mapping on the basis of DTM. Mapping of slope length, all other parameters known

Practices to limit erosion

Fixed to 1

11

Diffuse erosion risk map

Rainfall erosivity

Soil erodibility

Slopes

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Runoff production risk map

Calculated for each 10 x 10 m pixel

• Which part of rain will infiltrate?

• Thus, which part will stream??

• Soil Hydraulic groups mapping (on the basis of limit infiltration rate)

• Land use map and slope map

•  estimation of CN (SCS abstraction method USDA)

13

Runoff concentration risk map

• Risk definition (given for each pixel

by its catchment area)

< 1 ha : insignificant risk

1< area < 9 ha : low risk

9 < area < 18 ha : intermediate risk

> 18 ha : high risk

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http://cartographie.wallonie.be/NewPortailCarto/index.jsp?page=subMenuERRUISSOL&node=32&snode=321 ₁₅

In the field, let’s act!

Agronomical reality Technical constraints Economical objectives 16 « cover crops, vegetated strips, waterways, retention zones,… »

Avoid soil detachment and movment

To slow down and diffuse water Drive and stock water to improve its quality and protect outlets

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Exemple : proposal for in field and watershed management to be discussed with the

municipality and the farmers 17

- the right measures at the right places - at field and watershed levels

PESTICIDES TRANSFERTS BY DIFFUSE

RUNOFF & EROSION

TOPP S-PRO W AD IS St ak eh o ld er w o rk sh o p 04/04/2012

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Surface water transfert model

19 TOPP S-PRO W AD IS St ak eh o ld er w o rk sh o p 04/04/2012 Pesticide module PRZM PPP Properties

Pluviometric data Pedologic & hydrodynamic

parameters

Diffuse runoff simulation SCS method (ERRUISSOL)

Diffuse erosion simulation (MUSLE)

Quantity of PPP transfered to surface water

Kd/Koc/Kom <<  by Runoff Kd/Koc/Kom >>  by Erosion

• Jr,i : pesticide runoff loss from compartment i [mg m-2]

• DRIi : fraction dissolved-phase chemical present in

compartment i available for runoff [-]

• Cw i : concentration of dissolved pesticide in the water phase

[mg dm-3_]

• Q : amont of surface runoff [cm]

• 10 : unit correction factor (dm3_{to m}3_{& cm to m)}

PRZM : Pesticide runoff loss

Carsel & al (2003) – PPP runoff loss estimation:

10 .

.

_, ,

DRI

C

Q

J

_r_i _i _w_i ERRUISSOL

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PRZM : Pesticide runoff loss

Concentration of dissolved PPP in the topsoil water phase (Cwi)

• Retention phenomena (Freundlich adsorption & desorption isotherm) 21 TOPP S-PRO W AD IS St ak eh o ld er w o rk sh o p 04/04/2012 10 . . . _, , DRI C Q J_r_i _i _w_i

Cw

Cs

K

_d n f

Cw

K

Cs

.

K

_d

K

_oc

.

OC

• Cs : concentration of adsorbed PPP in the solid phase [mg kg-1_]

• Cw : concentration of dissolved PPP in the water phase [mg dm-3_]

• Kf / Kd : Freundlich coef./soil-water adsorption coef. [dm3_kg-1_]

• n : Freundlich exponent – affinity index of the PPP to the soil [-]

• Degradation phenomena (temporal first-order kinetics)

PRZM : Pesticide runoff loss

TOPP S-PRO W AD IS St ak eh o ld er w o rk sh o p 04/04/2012 10 . . . , , DRI C Q Jri i wi C DT C t C 50 2 ln . ) 50 2 ln exp( ) 0 ( ) exp( ) 0 ( ) ( t DT C t µ C t

C_tot _tot _tot

0 0.2 0.4 0.6 0.8 1 1.2 0 50 100 150 e-µt t (j)

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• Degradation phenomena (integration of the temporal first-order kinetics)

PRZM : Pesticide runoff loss

23 TOPP S-PRO W AD IS St ak eh o ld er w o rk sh o p 04/04/2012 10 . . . _, , DRI C Q J_r_i _i _w_i ) 50 2 ln exp( ) 0 ( ) exp( ) 0 ( ) ( t DT C t µ C t

C_tot _tot _tot

) . 50 2 ln exp( ). 0 ( . 2 ln 50 ) . 50 2 ln exp( ). 0 ( ) ( t DT C DT dt t DT C t

Ctot tot tot

t : [0 – 365 j]

.365) 1 50 2 ln exp( ). 0 ( . 2 ln 50 . 365 1 DT C DT

Ctot mean tot

• Ctot-mean : Average predicted total concentration in the soil layer

before the rainfall event

PRZM : Pesticide runoff loss

24 TOPP S-PRO W AD IS St ak eh o ld er w o rk sh o p 04/04/2012 10 . . . , , DRI C Q Jri i wi

.

,i i i tot

Cw

Cs

C

_tot_,_i

Cw

_i

.

Cw

_i

.

K

_d

.

, d i tot i

K

C

Cw

• Ctot,i : total concentration of PPP in the

soil layer i [mg dm-3_]

• θ : volumetric soil moisture at field capacity [dm3_dm-3_] • ρ : bulk density [kg dm-3_]

Cw

Kd

Cs

.

OC

K

_d _oc

.

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PRZM : Diffuse erosion

Carsel & al (2003) – PPP erosion loss estimation:

A

C

r

X

J

_e e om si

.

10 .

.

_,

• Je : Pesticide erosion loss [mg m-2]

• Xe : Event soil loss [t]

• A : Field size [ha]

• Csi : Concentration of adsorbed PPP in the solid phase in the top soil layer i [mg kg-1_]

• rom : Enrichment ratio for organic matter of sediments eroded from the topsoil surface [-]

• 10 : Unit correction factor (t to kg & ha to m2₎

MUSLE

PRZM : Diffuse erosion

TOPP S-PRO W AD IS St ak eh o ld er w o rk sh o p 04/04/2012

Xe : Event soil loss (MUSLE ; Williams, 1975):

P

C

LS

K

q

Q

X

_e

11 ,

8 .(

.

_p

)

0,56

.

• Xe : Event soil loss [t]

• Q : Volume of event runoff

• qp : peak storm runoff rate

• K : Soil erodibility

• C : Soil cover factor / crop management factor

• LS : Length-slope factor

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Total Pesticide loss by diffuse

runoff & erosion

Example for Isoproturon (DT50 : 23 d ; Koc : 36 dm³ kg-1₎

Rainfall of 34 mm

Total Pesticide loss by diffuse

runoff & erosion

Example for Mancozeb (DT50 : 5 d ; Koc : 174 dm³ kg-1₎

Rainfall of 34 mm

Agricultural plot at Baisy-Thy

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Laurent Vandendael Walloon Agricultural Research Center

Agriculture and Natural Environment

Soil Fertility & Water Protection PESTEAUX project [email protected]

http://www.cra.wallonie.be

Aurore Degré Ulg Gembloux Agro-Bio Tech

Soil – Water Systems ERRUISSOL project GISER project (www.giser.be)

[email protected] http://www.gembloux.ulg.ac.be/ha publications : http://orbi.ulg.ac.be ₂₉ TOPP S-PRO W AD IS St ak eh o ld er w o rk sh o p 04/04/2012