Aquanty Staff Research Highlight – Saturated hydraulic conductivity in northern peats inferred from other measurements
We are back with another exciting Aquanty staff research highlight! This time we’re highlighting a recently published article co-authored by Eric Kessel, a talented hydrogeologist and one of our newest team members. Congratulations Eric and the full team of researchers who contributed to this paper!
Morris et al. 2022 is a meta-analysis of 2507 peatland soil samples across Northern Canada and parts of Europe, which relates saturated hydraulic conductivity to depth and more commonly measured parameters like bulk density or the Van Post Humification Scale. Eric participated in the collection and laboratory or in-situ measurements of the peat samples surrounding the Fort McMurray Area (Alberta, Canada) during his graduate studies (MSc) in the Department of Geography and Environmental Management at the University of Waterloo. This is a helpful study, since the direct measurement of saturated hydraulic conductivity of peat (or any material) is quite an onerous task! The analysis "yielded highly skillful predictive equations" for Ksat, potentially providing a cheaper and simpler method of estimating this parameter critical to peatland hydrology.
Saturated hydraulic conductivity in northern peats inferred from other measurements
Morris, P.J., Davies, M.L., Baird, A.J., Balliston, N., Bourgault, M.-A., Clymo, R.S., et al. (2022). Saturated hydraulic conductivity in northern peats inferred from other measurements. In Water Resources Research. American Geophysical Union (AGU). https://doi.org/10.1029/2022wr033181
Abstract:
In northern peatlands, near-saturated surface conditions promote valuable ecosystem services such as carbon storage and drinking water provision. Peat saturated hydraulic conductivity (Ksat) plays an important role in maintaining wet surface conditions by moderating drainage and evapotranspiration. Peat Ksat can exhibit intense spatial variability in three dimensions, and can change rapidly in response to disturbance. The development of skilful predictive equations for peat Ksat and other hydraulic properties, akin to mineral soil pedotransfer functions, remains a subject of ongoing research. We report a meta-analysis of 2,507 northern peat samples, from which we developed linear models that predict peat Ksat from other variables, including depth, dry bulk density, von Post score (degree of humification), and categorical information such as surface microform type and peatland trophic type (e.g., bog, fen). Peat Ksat decreases strongly with increasing depth, dry bulk density and humification; and increases along the trophic gradient from bog to fen peat. Dry bulk density and humification are particularly important predictors, and increase model skill greatly; our best model, which includes these variables, has a cross-validated r2 of 0.75, and little bias. A second model that includes humification but omits dry bulk density, intended for rapid field estimations of Ksat, also performs well (cross-validated r2 = 0.64). Two additional models that omit several predictors perform less well (cross-validated r2 ∼ 0.5), and exhibit greater bias, but allow Ksat to be estimated from less comprehensive data. Our models allow improved estimation of peat Ksat from simpler, cheaper measurements.