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On infiltration and infiltration characteristic times
  • +14
  • Mehdi Rahmati,
  • Borja Latorre Garcés,
  • David Moret-Fernandez,
  • Laurent Lassabatère,
  • Nima Talebian,
  • Dane Gerard Miller,
  • Renato Morbidelli,
  • Massimo Iovino,
  • Vincenzo Bagarello,
  • Mohammad Reza Neyshabouri,
  • Ying Zhao,
  • Jan Vanderborght,
  • Lutz Weihermüller,
  • Rafael Angulo-Jaramillo,
  • Dani Or,
  • Rien van Genuchten,
  • Harry Vereecken
Mehdi Rahmati
Forschungszentrum Jülich GmbH

Corresponding Author:[email protected]

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Borja Latorre Garcés
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David Moret-Fernandez
Estación Experimental de Aula Dei (CSIC)
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Laurent Lassabatère
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Nima Talebian
Bond University
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Dane Gerard Miller
Bond University
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Renato Morbidelli
University of Perugia
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Massimo Iovino
University of Palermo
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Vincenzo Bagarello
Universita degli Studi
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Mohammad Reza Neyshabouri
University of Tabriz
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Ying Zhao
Ludong University
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Jan Vanderborght
Forschungszentrum Juelich
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Lutz Weihermüller
Forschungszentrum Jülich GmbH
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Rafael Angulo-Jaramillo
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Dani Or
ETH Zurich
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Rien van Genuchten
Federal University of Rio de Janeiro, UFRJ
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Harry Vereecken
Forschungszentrum Jülich GmbH
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In his seminal paper on solution of the infiltration equation, Philip (1957) proposed a gravity time, tgrav, to estimate practical convergence time of his infinite time series expansion, TSE. The parameter tgrav refers to a point in time where infiltration is dominated equally by capillarity and gravity derived from the first two (dominant) terms of the TSE expansion. Evidence that higher order TSE terms describe the infiltration process better for longer times. Since the conceptual definition of tgrav is valid regardless of the infiltration model used, we opted to reformulate tgrav using the analytic approximation proposed by Parlange et al. (1982) valid for all times. In addition to the roles of soil sorptivity (S) and saturated (Ks) and initial (Ki) hydraulic conductivities, we explored effects of a soil specific shape parameter β on the behavior of tgrav. We show that the reformulated tgrav (notably tgrav= F(β) S^2/(Ks - Ki)^2 where F(β) is a β-dependent function) is about 3 times larger than the classical tgrav given by tgrav, Philip= S^2/(Ks - Ki)^2. The differences between original tgrav, Philip and the revised tgrav increase for fine textured soils. Results show that the proposed tgrav is a better indicator for convergence time than tgrav, Philip. For attainment of the steady-state infiltration, both time parameters are suitable for coarse-textured soils, but not for fine-textured soils for which tgrav is too conservative and tgrav, Philip too short. Using tgrav will improve predictions of the soil hydraulic parameters (particularly Ks) from infiltration data as compared to tgrav, Philip.