NACREW
Québec 2013
Hôtel
Château Laurier
August 25-28, 2013 / 25 au 28 août 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
Kummer 2004
 Perched water table
 Heterogeneity of soil
profile
 Restrictive
hydraulic properties
in a layer
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
Atmospheric
conditions
 168 hours of simulation
 1D domain with 100 cm
 100 elements (101 nodes)
K
Se 
 Conditions
 Hydraulic (p1..p625)
 (n, α, Ks, θs )
 2 soil types
 Physical
 4 depths
 4 thicknesses
 Meteorological
 4 rainfalls
  r 
n m
 1    h  

s  r 
m
1 



l 
m 
K  Se   K s Se 1  1  Se  
 
 
n 1
m
n
2
(Mualem (1976) and van
Genuchten’s model (1980)
Seepage
face
h
K  E
x
Sensitivity analysis scheme
Model input file
Model HYDRUS 1D
Parameter
file
Numerical
traitement
SENSAN
Results
Configuration
Hydraulic parameters (n, α, Ks, θs )
Rain
p1
20
p2
40
p3
60
..p625
80
Output files
Depth
10
20
40
60
Thickness
5
10
20
40
Sensitivity calculations
 First-order sensitivity
index

S  p  p0  
p
 Gâteaux directional
derivative (Gâteaux, R, (1910))
SR, D,T 
Gâteaux, R

  p    p0 
 p  p0 
p0
  p0   p R, D,T   p0 R, D,T

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
-30 cm
Wet
Comfort
Zone
-70 cm
Dry
matric potential
(cm)
Matric potential at 48 h after the higher level
of water table
Hydraulic Properties: log K vs. h
 n and α
 Control the curve
shape
 At − 30 cm of matric
potential
 Drainage rate, 3 orders
less in the restrictive
soil layer
2
M1
M2
1
0
-1
-2
-3
-4
-5
-6
-7
0
30
60
|h| [cm]
90
120
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
Thank you!
Questions ?
Canneberges Bieler
Nature Canneberge
Transport Gaston Nadeau
Salzwedel Cranberry
Ferme Onésime Pouliot
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