Assessing the Short-term Impacts on Sediment Production following Rapid Harvest and Stream Crossing Decommissioning in Rocky Mountain Headwaters

• Author / Creator

  Corrigan, Amelia

• While rapid road and road-stream crossing decommissioning after forestry operations may serve to limit broader impacts of sedimentation in high value headwater streams, few studies have evaluated the combined effects of accelerated harvest operations and rapid retirement of roads on stream sediment. The objectives of this study were to evaluate the initial impacts of these management strategies on sediment production and fate during a short duration (10-month) harvesting operation in three headwater sub-catchments in the southwestern Rocky Mountains of Alberta, Canada. A multi-pronged sampling approach (automated ISCO samplers, event focused grab sampling, continuous wash load sampling, and sediment ingress measurements) was used to measure suspended sediment production and ingress in streambeds. Sediment inputs from forestry roads was generally much lower than has previously been reported with little, if any, consistent pattern of elevated sediment production during the snowmelt freshet or periodic summer rainstorms. The impact of the combined disturbance of rapid harvest (2015) and subsequent road decommissioning (2016) on total suspended solids (p = 0.52), wash load concentrations (p = 0.61), and sediment ingress (p = 0.33) was largely negligible. In fact, turbidity was often higher (p < 0.001) at the upstream sample location across both years. Minimal in-stream impacts on sediment from forest harvest and road-stream crossings was likely a reflection of combined factors including a) employment of secondary erosion control Best Management Practices to roads and bridge crossings, b) rapid decommissioning of roads and crossings to limit exposure of linear land disturbance features, and c) drier El Niño climatic conditions during the study.

• Subjects / Keywords

  • Best Management Practices
  • Sediment production
  • Logging roads

• Graduation date

  Fall 2017

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R33F4M25J

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.