On the Structure and Flow Processes in the Capillary Fringe of Phreatic Aquifers

Daniel Ronen, Harvey Scher, Martin Blunt

Research output: Contribution to journalArticlepeer-review

42 Scopus citations


The water distribution in the capillary fringe (CF) reflects the interaction of a strongly wetting fluid in a heterogeneous porous medium. Field profiles of gravimetric water content of the CF for a 30 m deep, sandy, phreatic aquifer in Israel are critically analyzed in the context of the possible wetting and drainage processes in these sediments. A highly plausible explanation of the profiles is based on the spatial configuration of the CF surface determined from a model of the movement of water within the porous medium. The structural types of CF that can arise from a number of competing pore-scale displacement mechanisms, in the presence of gravity, are characterized by the model. We differentiate between two generic types of CF structures: a tenuous invasion-percolation type and a compact type. Flow, in response to a horizontal pressure gradient, associated with each structure is analyzed. Our interpretation of the field data supports the compact structure with a spatial variation in the height of the CF surface, above the water table, on the order of 1 m. In this compact structure horizontal flow is characterized by stagnant regions in the CF above a critical height hc and flow only for regions below hc. The field water content (at hc) may be used to predict the onset of lateral water flow in the CF.

Original languageEnglish
Pages (from-to)159-180
Number of pages22
JournalTransport in Porous Media
Issue number2
StatePublished - 1 Jan 1997
Externally publishedYes


  • Capillary fringe
  • Multiphase flow
  • Network modeling
  • Saturated-unsaturated interface

ASJC Scopus subject areas

  • Catalysis
  • Chemical Engineering (all)


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