Advanced

Observing solute transport in the capillary fringe using image analysis and electrical resistivity tomography in laboratory experiments

Persson, Magnus LU ; Dahlin, Torleif LU and Günther, Thomas (2015) In Vadose Zone Journal 14(5).
Abstract
Five laboratory experiments were conducted to study solute transport in the capillary fringe in a sand filled glass tank containing an artificial groundwater zone, an unsaturated zone, and a capillary fringe in between. Dye stained water, applied at the soil surface, moved downwards through the unsaturated zone and then horizontally in the capillary fringe. The horizontal velocity of the dye plume front was calculated using optical image analysis and Electrical Resistivity Tomography (ERT) measurements. Both methods gave similar velocities if an appropriate value of the threshold ratio describing the dye front was used. The hydraulic model HYDRUS-2D was used to simulate dye movement in the glass tank. After calibrating the dispersivity... (More)
Five laboratory experiments were conducted to study solute transport in the capillary fringe in a sand filled glass tank containing an artificial groundwater zone, an unsaturated zone, and a capillary fringe in between. Dye stained water, applied at the soil surface, moved downwards through the unsaturated zone and then horizontally in the capillary fringe. The horizontal velocity of the dye plume front was calculated using optical image analysis and Electrical Resistivity Tomography (ERT) measurements. Both methods gave similar velocities if an appropriate value of the threshold ratio describing the dye front was used. The hydraulic model HYDRUS-2D was used to simulate dye movement in the glass tank. After calibrating the dispersivity value in the hydraulic model the horizontal velocity was found to be in the range -10 to +17 % compared to the values measured using image analysis and -12 to +24 % compared to the values measured by ERT, the differences could probably be attributed to uncertainties in the hydraulic parameters and soil heterogeneities. Both experimental and numerical results showed that the horizontal velocity of the capillary fringe is more or less identical to the one in the saturated zone. Thus, from a water transport perspective, the results suggest that the capillary fringe should be treated as a part of the saturated zone in hydrological modelling. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Vadose Zone Journal
volume
14
issue
5
publisher
Soil Science Society of America
external identifiers
  • wos:000362064600004
  • scopus:84929353470
ISSN
1539-1663
DOI
10.2136/vzj2014.07.0085
language
English
LU publication?
yes
id
ece49e41-708f-45f1-809e-1bd770aecf20 (old id 4935057)
date added to LUP
2015-07-20 10:23:04
date last changed
2017-03-05 03:44:03
@article{ece49e41-708f-45f1-809e-1bd770aecf20,
  abstract     = {Five laboratory experiments were conducted to study solute transport in the capillary fringe in a sand filled glass tank containing an artificial groundwater zone, an unsaturated zone, and a capillary fringe in between. Dye stained water, applied at the soil surface, moved downwards through the unsaturated zone and then horizontally in the capillary fringe. The horizontal velocity of the dye plume front was calculated using optical image analysis and Electrical Resistivity Tomography (ERT) measurements. Both methods gave similar velocities if an appropriate value of the threshold ratio describing the dye front was used. The hydraulic model HYDRUS-2D was used to simulate dye movement in the glass tank. After calibrating the dispersivity value in the hydraulic model the horizontal velocity was found to be in the range -10 to +17 % compared to the values measured using image analysis and -12 to +24 % compared to the values measured by ERT, the differences could probably be attributed to uncertainties in the hydraulic parameters and soil heterogeneities. Both experimental and numerical results showed that the horizontal velocity of the capillary fringe is more or less identical to the one in the saturated zone. Thus, from a water transport perspective, the results suggest that the capillary fringe should be treated as a part of the saturated zone in hydrological modelling.},
  author       = {Persson, Magnus and Dahlin, Torleif and Günther, Thomas},
  issn         = {1539-1663},
  language     = {eng},
  number       = {5},
  publisher    = {Soil Science Society of America},
  series       = {Vadose Zone Journal},
  title        = {Observing solute transport in the capillary fringe using image analysis and electrical resistivity tomography in laboratory experiments},
  url          = {http://dx.doi.org/10.2136/vzj2014.07.0085},
  volume       = {14},
  year         = {2015},
}