Changes to the hydrology of a boreal fen following the placement of an access road and below ground pipeline

Abstract

Study region: A channel fen in the Athabasca Oil Sands Area, Alberta, Canada Study focus: We assessed the hydrological changes to the hydrology of a moderate-rich fen after the construction of a road (perpendicular to flow) in 2003 and a pipeline (obliquely to flow) in 2011. New hydrological insights for the region: Flow obstruction was most prominent where the fen intersected the road. Changes to hydrophysical properties from pipeline construction were most pronounced in the top 10 cm of peat, which demonstrated significantly higher bulk density (by 170% and 112%) and lower hydraulic conductivity (by 94% and 91%) above the buried pipeline and in adjacent cleared locations, respectively, relative to areas not cleared or directly disturbed during pipeline development. Changes to water table levels from the pipeline were more pronounced farther down-gradient as the pipeline cut through the fen obliquely to direction of flow, and water tables became more variable on the side where the flow face had decreased in length. If built through peatlands, pipelines should be oriented parallel to flow direction and located along the central axis of the fen. Additional culverts should be considered in the event of building a pipeline through an already existing road to facilitate flow on either side.

Keywords

• Athabasca oil sands area
• Wetlands
• Fen
• Hydrological alteration
• Linear disturbances