Author(s): Gregory Courtice, Bahman Naser, Deborah Roberts, Bernard Bauer

Linked Author(s):

Keywords: In-stream construction; Suspended sediment; Riverine ecosystems; Sediment transport; River engineering;

Abstract: The City of Calgary (Alberta, Canada) proposes to conduct a gravel relocation project within the Bow River that is deemed of environmental importance. Unfortunately, under the traditional management framework based on fixed suspended sediment concentration limits, the project cannot be implemented. It is argued that concentration-based criteria do not reflect environmentally acceptable thresholds. A theoretical in-stream construction-induced suspended sediment (ICISS) exposure risk model was used to compare ecosystem stress predictions for varying rates of gravel placement activities. The model combines suspended sediment dosage-effect relationships from the literature and a sediment transport model that predicts plume dispersion in the downstream of the construction activities. An optimum construction approach and ICISS management strategy were devised based on environmental and economic considerations. Results indicate that a duration-based management framework provides greater flexibility and effectiveness, which will enable the project to proceed. The approach will assist in the management of future projects anticipated to create dynamic ICISS releases by providing a framework that supports consistent and effective management strategies for highly variable and complex river construction projects.

DOI: https://doi.org/10.3850/38WC092019-1342

Year: 2019