Predicting air permeability in undisturbed, subsurface sandy soils from air-filled porosity

Tjalfe G. Poulsen*, Per Moldrup, Anne Thorbjørn, Per Schjønning

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


A model for predicting air permeability (ka) as function of air-filled porosity (ε) in undisturbed subsurface sandy soils, relevant for vapor extraction system design and operation, was developed using data from eight undisturbed soils (approximately 240 samples). The model requires only one measurement of corresponding values of ka and ε as input to estimate ka at any desired value of ε. The soils used represent both urban, agricultural and forest locations. The model is based on the fact that the relationships between log (ka) and log(ε) in sandy soils are approximately linear and on average pass through a common interception point, although with very different slopes. An expression for predicting ka at -100 cm H2 O soil water potential (ka100) from ε at the same potential (ε100) for sandy soils was also developed. Using this expression together with the new ka (ε) predictive model enables prediction of the entire ka (ε) relation without any ka measurements using only a measurement of ε100. This approach results in only a slightly higher prediction uncertainty. The model was tested against an independent set of data from five undisturbed sandy soils (22 samples) and close agreement between measured and predicted air permeability values was found.

Original languageEnglish
Pages (from-to)995-1001
Number of pages7
JournalJournal of Environmental Engineering, ASCE
Issue number10
StatePublished - 2007
Externally publishedYes


  • Permeability
  • Porosity
  • Predictions
  • Sand
  • Soil pollution


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