COMPARISONS OF TWO MODELS FOR PREDICTING THE RELATIVE HYDRAULIC CONDUCTIVITY OF SALT-AFFECTED SWELLING SOILS

Macroscopic swelling (MS) of samples from two montmorillonitic soils of the Sudan increased as the exchangeable sodium percentage (ESP) increased and as the electrolyte concentration (C) of mixed-salt solutions decreased. Threshold ESP values existed with significant swelling occurring beyond such threshold levels. Macroscopic swelling accounted for 86 and 71 percent of the variability of the relative hydraulic conductivity (RHC) of the two soils, respectively. Macroscopic swelling data qualitatively fitted McNeal's (1968) demixed-ion model, especially beyond the treshold ESP values. The fit was essentially quantitative for soils of ESP is less than 50. Generally, deviations of theoretical interlayer swelling values from experimental MS values increased with ESP, with maximum theoretical values being 3 to 15 times experimental values. Interlayer swelling values were found to account for about 98 percent of the variability in MS values for the two soils, and accountef for 87 and 75 percent of the variability in RHC of the two soils, respectively. The agreement between predicted and experimental RHC was fairly good for solutions of SAR greater than or equal to 50 but poorer for lower SAR values. The Lagerwerff et al. (1969) mixed-ion model failed to predict MS both qualitatively and quantitatively. However, agreement between calculated and experimental RHC was found to be fairly good, even for this model. /Author/

  • Corporate Authors:

    Lippincott Williams & Wilkins

    428 East Preston Street
    Baltimore, MD  USA  21202
  • Authors:
    • Mustata, M A
    • Hamid, K S
  • Publication Date: 1977-3

Media Info

  • Pagination: p. 149
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00156068
  • Record Type: Publication
  • Source Agency: Soil Science
  • Files: TRIS
  • Created Date: Aug 4 1977 12:00AM