The effect of water content on solute transport in unsaturated porous media

Ingrid Y. Padilla, Tian-Chyi J Yeh, Martha H. Conklin

Research output: Contribution to journalArticle

119 Citations (Scopus)

Abstract

The effect of water content on NaCl transport in unsaturated porous media was investigated under steady state flow conditions for water contents ranging between full saturation and 15% by volume. The experiments were conducted in a 25 cm column packed with homogeneous sand. Results of the experiments indicate that solute transport in unsaturated porous media is subject to greater velocity variations and slower solute mixing than one in saturated media. As a result, NaCl breakthrough curves (BTCs) show earlier initial arrival and greater tailing and variance as the average water content decreases. These results suggest that transport processes in our experiments have not fully developed to the Fickian regime at lower water contents. Because the classical convection-dispersion equation does not adequately describe the movement of solutes under the pre-Fickian regime, a mobile-immobile model was employed to reproduce the BTCs obtained under unsaturated conditions. In general, the results indicate that at lower water contents the medium has a greater fraction of immobile water, higher dispersion, and slower mass transfer between the mobile and immobile regions. A power law relationship between dispersion and water content-normalized velocities was found to exist for our experiments and other experiments reported in the literature using different porous media. Thus we suggest dispersivity is not only a function of properties of the media but also of water content.

Original languageEnglish (US)
Pages (from-to)3303-3313
Number of pages11
JournalWater Resources Research
Volume35
Issue number11
DOIs
StatePublished - 1999

Fingerprint

Solute transport
soil transport processes
porous media
solute transport
Water content
Porous materials
porous medium
water content
breakthrough curve
experiment
Experiments
solute
unsaturated conditions
saturated medium
dispersivity
Tailings
effect
mass transfer
transport process
tailings

ASJC Scopus subject areas

  • Aquatic Science
  • Environmental Science(all)
  • Environmental Chemistry
  • Water Science and Technology

Cite this

The effect of water content on solute transport in unsaturated porous media. / Padilla, Ingrid Y.; Yeh, Tian-Chyi J; Conklin, Martha H.

In: Water Resources Research, Vol. 35, No. 11, 1999, p. 3303-3313.

Research output: Contribution to journalArticle

Padilla, Ingrid Y. ; Yeh, Tian-Chyi J ; Conklin, Martha H. / The effect of water content on solute transport in unsaturated porous media. In: Water Resources Research. 1999 ; Vol. 35, No. 11. pp. 3303-3313.
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