Understanding sediment dynamics using geological and engineering approaches: A case study of the buffalo river area of concern, Buffalo, New York

A combination of geological and engineering approaches was applied to better understand sediment movement along a contaminated river bed and provide support for remediation decision making. The geological approach, using sediment trend analysis (STA) and side‐scan sonar mapping, helps interpret sedimentary processes acting over longer terms, while the engineering approach, based on a three‐dimensional sediment transport model, illustrates sediment movement over shorter times, such as might be driven by storm events. The study site was the lower portions of the Buffalo River (Buffalo, NY), which is a tributary to Lake Erie and is an Area of Concern (AoC), as identified by the International Joint Commission due to beneficial use impairments primarily associated with contaminated sediment. Results from STA indicate two distinct flow regimes: a downstream regime dominated by fluvial processes and an upstream regime driven by changes in the level of Lake Erie. Where the two flow regimes intersect, sediment furrows are found. These features have been observed in this portion of the river over the past fifteen years and show characteristic ‘tuning forks’ opening in both upstream and downstream directions, indicating a bidirectional flow regime. Upstream movement of sediment also was found with the sediment transport model, which links hydrodynamic and particle tracking components to calculate transport pathways. Such movement is apparently generated by high amplitude seiches common to Lake Erie. Upstream sediment transport was not expected, but is consistent with the interpretation of results from each of the three different approaches. This combination of techniques has provided insights about short‐term and longer‐term sedimentation processes, which is helpful in choosing among management and remediation options for river restoration.