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

Abstract

Water 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.

Aquifer-Peatland Hydrological Connectivity and Controlling Factors in Boreal Peatlands

“…As expected, the observed decreasing K with depth and the range of values compared reasonably well with those of other studies (Beckwith et al, 2003;Surridge et al, 2005;Rosa and Larocque, 2008;Bourgault et al, 2018). The decreasing trends with depth are similar to those reported by Beckwith et al (2003) and Surridge et al (2005) for peatlands located in the United Kingdom.…”

Effects of water level alteration on carbon cycling in peatlands

“…Notably, peat subsidence and change in peat properties have been widely observed after drainage, which further accelerates microbial decomposition and C loss (Whittington and Price 2006) in boreal (Rothwell, Silins, and Hillman 1996;Minkkinen and Laine 1998;Olefeldt et al 2017;McPartland et al 2019), temperate (Price and Schlotzhauer 1999;Strack and Waddington 2007;Waddington et al 2010a;Hribljan 2012;Potvin et al 2015;Schulte et al 2019) and tropical peatlands (Khasanah and van Noordwijk 2019;Peacock et al 2019). Peat property changes include loss of soil C contents, increased bulk density and vertical hydraulic gradient, reduced porosity, decreased saturated hydraulic conductivity and a greater pore water residence time (Weiss et al 1998;Price 2003;Whittington and Price 2006;Berger et al 2018;Bourgault et al 2018). Meanwhile, these properties may not be regained after the restoration of natural hydrology, even for decades (Schimelpfenig, Cooper, and Chimner 2014;Lazcano et al 2018;Schulte et al 2019;Emsens et al 2020).…”

Saturated Hydraulic Conductivity in Northern Peats Inferred From Other Measurements

“…Fresh plant litter is commonly highly permeable but as it decomposes to form peat, pore spaces close and collapse and become increasingly disconnected. Strong vertical gradients are commonly observed in peat K sat , which can decline by several orders of magnitude across the uppermost few decimeters of a peat profile (e.g., Bourgault et al., 2018; Clymo, 1992; Holden & Burt, 2003; McCarter et al., 2020; Menberu et al., 2021; Ronkanen & Kløve, 2005). Peat hydraulic properties can be affected by both natural and anthropogenic disturbances.…”