Comment on 'Modified expression for unsaturated hydraulic conductivity according to Mualem–van Genuchten to allow proper computations at low pressure heads' by M. Heinen

Autor: Marcia S. Batalha, Camila R. Bezerra‐Coelho, Elizabeth M. Pontedeiro, Martinus Th vanGenuchten, Jian Su
Jazyk: angličtina
Rok vydání: 2024
Předmět:
Zdroj: Vadose Zone Journal, Vol 23, Iss 4, Pp n/a-n/a (2024)
Druh dokumentu: article
ISSN: 1539-1663
DOI: 10.1002/vzj2.20332
Popis: Abstract This comment concerns evaluation of the Mualem–van Genuchten (MvG) unsaturated soil hydraulic functions at very low (negative) pressure heads as described recently in an important study by Heinen. He showed that below some critical pressure head, the unsaturated hydraulic conductivity should be approximated by a power function, even when evaluated using double precision computations. We show that a more precise approximation is possible when the approximation is formulated in terms of effective fluid saturation (Se) rather than the pressure head, h. More general constraints are also provided when the approximated hydraulic conductivity equation should be used. The alternative formulation and constraints were implemented earlier in the SOHYP and RETC software packages.
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