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Hôtel Château Laurier August 25-28, 2013 / 25 au 28 août 2013 NACREWNACREW Québec 2013

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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.

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Introduction Need an optimal water management Perched water table Heterogeneity of soil profile Restrictive hydraulic properties in a layer Kummer 2004 Pressure head

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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

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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

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Methodology (Directional Sensitivity Analysis)

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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)

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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 p1 20 10 5 p2 40 20 10 p3 60 40 20..p625 80 60 40 Parameter file Model input file Results

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Sensitivity calculations First-order sensitivity index Gâteaux directional derivative ( Gâteaux, R, (1910) ) Gâteaux, R

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Results

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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

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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

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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

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Conclusions Perched water table Diagnosis Measurement & calculation Numerical study Identified conditions causing perched water table n and α high effect on drainage efficiency

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Canneberges Bieler Nature Canneberge Transport Gaston Nadeau Salzwedel Cranberry Ferme Onésime Pouliot Thank you! Questions ?

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Thank you ! Special thanks to our sponsors Un merci spécial à nos commanditaires

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