[1091] - Horizontal soil water potential heterogeneity: simplifying approaches for crop water dynamics models

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Couvreur, V., Vanderborght, J., Beff, L., Javaux, M., 2014. Horizontal soil water potential heterogeneity: simplifying approaches for crop water dynamics models. Hydrology and Earth System Sciences, 18, 1723 - 1743. DOI: 10.5194/hess-18-1723-2014.
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Title(s):Main Title: Horizontal soil water potential heterogeneity: simplifying approaches for crop water dynamics models
Description(s):Abstract: Soil water potential (SWP) is known to affect plant water status, and even though observations demonstrate that SWP distribution around roots may limit plant water availability, its horizontal heterogeneity within the root zone is often neglected in hydrological models. As motive, using a horizontal discretisation significantly larger than one centimeter is often essential for computing time considerations, especially for large-scale hydrodynamics models. In this paper, we simulate soil and root system hydrodynamics at the centimeter scale and evaluate approaches to upscale variables and parameters related to root water uptake (RWU) for two crop systems: a densely seeded crop with an average uniform distribution of roots in the horizontal direction (winter wheat) and a wide-row crop with lateral variations in root density (maize). In a first approach, the upscaled water potential at soil–root interfaces was assumed to equal the bulk SWP of the upscaled soil element. Using this assumption, the 3-D high-resolution model could be accurately upscaled to a 2-D model for maize and a 1-D model for wheat. The accuracy of the upscaled models generally increased with soil hydraulic conductivity, lateral homogeneity of root distribution, and low transpiration rate. The link between horizontal upscaling and an implicit assumption on soil water redistribution was demonstrated in quantitative terms, and explained upscaling accuracy. In a second approach, the soil–root interface water potential was estimated by using a constant rate analytical solution of the axisymmetric soil water flow towards individual roots. In addition to the theoretical model properties, effective properties were tested in order to account for unfulfilled assumptions of the analytical solution: non-uniform lateral root distributions and transient RWU rates. Significant improvements were however only noticed for winter wheat, for which the first approach was already satisfying. This study confirms that the use of 1-D spatial discretisation to represent soil–plant water dynamics is a worthy choice for densely seeded crops. For wide-row crops, e.g. maize, further theoretical developments that better account for horizontal SWP heterogeneity might be needed in order to properly predict soil–plant hydrodynamics in 1-D.
Identifier(s):DOI: 10.5194/hess-18-1723-2014
Responsible Party
Creator(s):Author: Valentin Couvreur
Author: Jan Vanderborght
Author: Laure Beff
Author: Mathieu Javaux
Publisher:European Geosciences Union
TR32 Topic:Vegetation
Subject(s):CRC/TR32 Keywords: Soil Water, Crop/s, Spatial Discretization, RWU
File Details
File Name:Couvreur_hess_2014.pdf
Data Type:Text
Size(s):21 Pages
File Size:3919 kB (3.827 MB)
Date(s):Available: 2014-05-12
Mime Type:application/pdf
Data Format:PDF
Download Permission:OnlyTR32
General Access and Use Conditions:According to the TR32DB data policy agreement.
Access Limitations:According to the TR32DB data policy agreement.
Licence:TR32DB Data policy agreement
North:-no map data
Measurement Region:None
Measurement Location:--None--
Specific Informations - Publication
Article Type:Journal
Source:Hydrology and Earth System Sciences
Number Of Pages:21
Page Range:1723 - 1743
Metadata Details
Metadata Creator:Tanja Kramm
Metadata Created:2014-09-22
Metadata Last Updated:2014-09-22
Funding Phase:2
Metadata Language:English
Metadata Version:V40
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