Quantifying peat hydrodynamic properties and their influence on water table depths in peatlands of southern Quebec (Canada)

Abstract

AbstractWater table depth in peatlands is strongly linked to physical properties of the peat, such as density (ρdry), peat composition and humification, hydraulic conductivity (K), and specific yield (Sy). Dry bulk density and peat depth are commonly used as indicators of K in ecohydrological models. However, no mathematical relationship exists to quantify Sy based on K and ρdry. As a result, ecohydrological models cannot explicitly reproduce the strong buffering capacity of peatlands. The objectives of this study were to analyse the literature‐reported mathematical link between all the physical properties to develop new mathematical relationships between these parameters and to evaluate whether variations in the physical properties of the peat control water table depth in peatlands. Seven peatlands located in the St. Lawrence Lowlands (Québec, Canada) were sampled, and 1 m long peat cores were collected from up‐gradient, mid‐gradient, and down‐gradient zones. All cores were used to measure ρdry, K, Sy, and to estimate peat composition and humification. Statistically significant correlations were found between (a) K and Sy (log–log model), (b) K and depth (log–log model), (c) Sy and depth (log–log model), (d) ρdry and Sy (log model), and (e) ρdry and K (log model). No significant difference was found in either K or Sy between sites. However, significant differences were found in water table depths. Because they provide a fuller description of the peat properties that control water table depths, these newly developed functions have the potential to improve the capacity of ecohydrological models to simulate time‐varying hydrological conditions.