Hôtel Château Laurier August 25-28, 2013 / 25 au 28 août 2013 NACREWNACREW Québec 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 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  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, K s )  (n, α, K s, θ s )  2 soil types  Physical  4 depths  4 thicknesses  Meteorological  4 rainfalls Seepage face Atmospheric conditions (Mualem (1976) and van Genuchten’s model (1980)

Sensitivity analysis scheme Model HYDRUS 1D Output files Numerical traitement SENSAN Configuration Hydraulic parameters (n, α, K s ) Hydraulic parameters (n, α, K s, θ s ) Rain Depth Thickness Rain Depth Thickness p p p p Parameter file Model input file Results

Sensitivity calculations  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

First-order sensitivity index  (p1..p25)  (n, α, K s )  (n, α, K s, θ s )  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 Bieler Nature Canneberge Transport Gaston Nadeau Salzwedel Cranberry Ferme Onésime Pouliot Thank you! Questions ?

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