Electronic Thesis and Dissertation Repository

Degree

Master of Engineering Science

Program

Civil and Environmental Engineering

Supervisor

Dr. Andrew Binns

2nd Supervisor

Dr. Timothy Newson

Joint Supervisor

Abstract

Severe weather events are occurring more frequently with extreme repercussions as our climate changes. Rainfall events of large magnitudes can lead to instability of river banks, riverbed erosion, and alterations in stream planform alignment. It is important to understand the hydraulic and geomorphic response of rivers and streams to storm events to predict long term morphological change, protect hydraulic structures, and manage aquatic ecosystems. The goal of this thesis is to examine the influence of precipitation events of varying magnitude on the morphodynamic processes of an urban creek. Four events are simulated: a constant averaged flow of 1.249 m3/s representative of the average flow in the creek over a 5-year period, a 5- year return period event, a 10-year return period event, and a 100-year return period event.

Channel modifications are made to four cross sections at the downstream end of Spencer Creek in order to investigate the effect of planform alignment and geometry on increased flood resiliency and channel stability. The first modification widened the channel at these sections, while the second modification lengthened the channel at these sections to be representative of increased meandering (and corresponding decrease in stream bed slope) of the creek. In general, the sediment concentration changed with each event, with the largest sediment concentration in the channel occurring for the 100-year return period event. The first modification to the channel demonstrated the largest reduction in velocity, sediment concentration, and shear stress at all cross sections for all events. The second modification demonstrated little to no change in velocity and shear stress for all events. The results from this thesis provide a framework for analyzing the morphodynamic response of urban streams to storm events of varying return periods and durations and will assist river engineers and hydrologists in managing and restoring urban creeks to mitigate flooding while balancing erosion and ecological processes.

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