Hôtel Château LaurierAugust 25-28, 2013 / 25 au 28 août 2013

NACREWQuébec 2013

Impact of vertical variability of soil hydraulic properties on

drainage efficiency in cranberry production

Yann Périard, M. Sc.Silvio Gumiere, ing., Ph. D.

Alain N. Rousseau, ing., Ph. D.Jean Caron, agr., Ph. D.

Introduction

Need an optimal water management

Perched water table

Heterogeneity of soil profile Restrictive

hydraulic properties in a layer

Kummer 2004

Simulation of perched water table

Pressure head

Diagnosis of perched water table

Calculated with Tx3 (Hortau)

Measured with Water Level Logger

Soil Water Potential=Water Table Depth ? Formation of a

restrictive layer

Numerical simulation of perched water table

Simulation with finite element model Hydrus 2D/3D

Good prediction

Now we can do a numerical study 40 000

simulations

Methodology(Directional Sensitivity Analysis)

Boundary conditions

168 hours of simulation 1D domain with 100 cm 100 elements (101 nodes)

Conditions Hydraulic (p1..p625)

(n, α, Ks, θs ) 2 soil types

Physical 4 depths 4 thicknesses

Meteorological 4 rainfalls

Seepage face

Atmospheric conditions

hK K Ex

2

1

1

1 1

1

mnre

s r

ml m

e s e e

S h

K S K S S

nmn

(Mualem (1976) and van Genuchten’s model (1980)

Sensitivity analysis scheme

Model HYDRUS 1D

Output files

Numerical traitementSENSAN

Configuration Hydraulic parameters (n, α, Ks, θs )

Rain Depth Thicknessp1 20 10 5p2 40 20 10p3 60 40 20..p625 80 60 40

Parameter file

Model input file

Results

Sensitivity calculations

0 0, , , ,, ,

R D T R D TR D T

p p pS

0

00

0p

p pS p p

p p p

First-order sensitivity index

Gâteaux directional derivative (Gâteaux, R, (1910))

Gâteaux, R

Results

Matric potential at 48 h after the higher level of water table

Conditions 10 cm of depth 10 cm of thickness 40 mm of rain

With n and α high Drainage norm is not

respected matric potential

(cm)

Comfort Zone

Dry

Wet-30 cm

-70 cm

Matric potential at 48 h after the higher level of water table

n and α Control the curve

shape At − 30 cm of matric

potential Drainage rate, 3

orders less in the restrictive soil layer

-7

-6

-5

-4

-3

-2

-1

0

1

2

0 30 60 90 120

|h| [cm]

M1 M2

Hydraulic Properties: log K vs. h

First-order sensitivity index

(p1..p25) (n, α, Ks, θs )

n and α high effect on

matric potential at 48 h

Sensitive hydraulic parameters

Conclusions

Perched water table Diagnosis Measurement &

calculation

Numerical study Identified conditions

causing perched water table

n and α high effect on

drainage efficiency

Canneberges BielerNature Canneberge

Transport Gaston NadeauSalzwedel Cranberry

Ferme Onésime Pouliot

Thank you!

Questions ?

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