Peat deformation and biogenic gas bubbles control seasonal variations in peat hydraulic conductivity

Nicholas Kettridge*, Erik Kellner, Jon Price, James Michael Waddington

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)


The hydraulic conductivity (K) of peat beneath the water table varies over short (annual) periods. Biogenic gas bubbles block pores and reduce K, and seasonal changes in the water table position cause peat deformation, altering peat pore size distribution. Although it has been hypothesized that both processes reduce K during warm dry summer conditions, temporal variations in K under field conditions have been explained previously by peat volume changes (strain) alone. We determine the effect of both controls on K by monitoring changes in gas content (Δγ), strain and K within a poor fen. Over the growing season, K decreased by an order of magnitude. In the near-surface peat (0.3-0.7m), this reduction is more strongly correlated with Δγ, providing the first field-based evidence that biogenic gas bubbles reduce K. In the deeper peat (0.7-1.3m), K is correlated principally with strain. However, causality is uncertain because of multicollinearity between strain and Δγ. To mitigate for multicollinearity, we took advantage of a peatland drainage experiment where the water table was artificially dropped at the beginning of the growing season, reducing correlations between strain and Δγ. Δγ remained the primary cause of K variations just beneath the water table at a depth of 0.5-0.7m, although further down through the peat profile (0.7-1.2m) changes in K were controlled by strain. We suggest that the larger pore structure of the poorly decomposed peat just below the water table is impacted less by volume changes than that of the more decomposed peat at depth. However, within this poorly decomposed peat, K is reduced by the high gas contents that result from higher rates of methane production.

Original languageEnglish
Pages (from-to)3208-3216
Number of pages9
JournalHydrological Processes
Issue number22
Early online date6 Jul 2012
Publication statusPublished - 30 Oct 2013


  • Deformation
  • Gas bubbles
  • Hydraulic conductivity
  • Methane
  • Peat

ASJC Scopus subject areas

  • Water Science and Technology


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