Hydrological hotspots in blanket peatlands: Spatial variation in peat permeability around a natural soil pipe

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Abstract

[1] Measurements were made of the hydraulic conductivity (K) of peat around a natural soil pipe in a blanket bog. This is the first investigation of decimeter-scale variability in both vertical K and horizontal K in blanket peats, which were found to be higher than indicated by previous research. This information suggests that it may be appropriate to reconsider (I) the spatial sampling strategies employed to investigate subsurface flow in blanket peatlands, and (II) how field data are used to parameterize flow models. Critically, there was spatial structure in the heterogeneity, with a wedge of high-K peat directly above the pipe forming a hydrological conduit between near-surface peat and the perennially flowing pipe. There was also significantly greater horizontal K parallel to the pipe's orientation compared with horizontal K perpendicular to the pipe. Determinations of the triaxial anisotropy of K, undertaken for the first time in peat soils, revealed substantial directional variations in K. The K around the pipe-peat interface was investigated; however, sample length dependency of K for peat samples precluded the investigation of a hypothesized low-K skin around the pipe.

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