Skip to Main content Skip to Navigation
Journal articles

Soil Water Retention : II. Derivation and Application of Shape Index

Feike J. Leij 1 Randel Haverkamp 2 Carlos Fuentes 3 Felipe Zatarain 3 P.J. Ross 4
1 Department of Civil Engineering [Long Beach]
2 LTHE - Laboratoire d'étude des transferts en hydrologie et environnement
3 IMTA - Instituto Mexicano de Tecnología del Agua
4 CSIRO - Commonwealth Scientific and Industrial Research Organisation [Canberra]
Abstract : The concept of a shape index was introduced in Part I to characterize the water retention curve. A potential problem with the parameterization of retention data is the interdependency of parameter values and their conversion to other parametric models. In this Part II the shape index is used to derive formulae for the conversion between: (i) hydraulic parameters of the Brooks-Corey (BC) and van Genuchten (vG) equations, (ii) parameter sets with and without the constraint that the residual water content r = 0, and (iii) vG-shape parameters with different constraints. The dependency of hydraulic parameters on the optimization strategy and the applicability of conversion equations were investigated with 660 retention curves from the GRIZZLY database. The BC-shape parameter and the vG-shape factor mn are poorly correlated for larger and mn (overall r2 = 0.96 for r = 0). Instead of the commonly used equality = mn, conversion based on the shape indices PBC and PvG is more accurate (r2 = 0.99). The shape index is also convenient to accurately predict shape parameters for different constraining scenarios involving r and m = 1 – k/n. The values for r and the shape parameters and mn are not unique. They are positively correlated to maintain the same soil water capacity for a particular soil. For the optimization of parameters, we recommend constraining r. Accurate optimization of retention data, in particular the shape parameters, is possible by constraining r to a non-zero value inferred from the shape index.
Document type :
Journal articles
Complete list of metadata
https://hal-insu.archives-ouvertes.fr/insu-00382124
Contributor : Thierry Pellarin Connect in order to contact the contributor
Submitted on : Thursday, May 7, 2009 - 1:34:14 PM
Last modification on : Tuesday, October 19, 2021 - 6:58:04 PM

Identifiers

Collections

INSU | CNRS | IRSTEA | UNIV-SAVOIE | INRAE | UGA

Citation

Feike J. Leij, Randel Haverkamp, Carlos Fuentes, Felipe Zatarain, P.J. Ross. Soil Water Retention : II. Derivation and Application of Shape Index. Soil Science Society of America Journal, Soil Science Society of America, 2005, 69, pp.1891 à 1901. ⟨10.2136/sssaj2004.0226⟩. ⟨insu-00382124⟩

Export

BibTeX TEI DC DCterms EndNote Datacite

Share

Metrics

Record views

110