Western University Scholarship@Western Electronic Thesis and Dissertation Repository 7-27-2017 12:00 AM Morphodynamic Response of Spencer Creek to Large Precipitation Events and Channel Modifications: A Case Study Emily Mae Martin The University of Western Ontario Supervisor Dr. Andrew Binns The University of Western Ontario Joint Supervisor Dr. Timothy Newson The University of Western Ontario Graduate Program in Civil and Environmental Engineering A thesis submitted in partial fulfillment of the equirr ements for the degree in Master of Engineering Science © Emily Mae Martin 2017 Follow this and additional works at: https://ir.lib.uwo.ca/etd Part of the Environmental Engineering Commons Recommended Citation Martin, Emily Mae, "Morphodynamic Response of Spencer Creek to Large Precipitation Events and Channel Modifications: A Case Study" (2017). Electronic Thesis and Dissertation Repository. 4870. https://ir.lib.uwo.ca/etd/4870 This Dissertation/Thesis is brought to you for free and open access by Scholarship@Western. It has been accepted for inclusion in Electronic Thesis and Dissertation Repository by an authorized administrator of Scholarship@Western. For more information, please contact [email protected]. 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. Keywords Mathematical modeling, sediment transport, channel modification, rivers and streams, hydraulic modeling i Acknowledgments I would like to express my extreme gratitude towards my supervisors Dr. Andrew D. Binns and Dr. Tim Newson for providing me with this opportunity. Thank you for your guidance, support, encouragement, advice, and financial support throughout my degree. Thank you to my research group, the Binns Group, for their support and assistance throughout my degree. I would like specifically to thank Etta Gunsolus for motivating and inspiring me when times were tough. Her ability to find the silver lining in any situation helped me when life didn’t go as planned. This thesis would not have been possible without the love and support of my family and friends. Thank you to my parents, Lori and Terry, for always pushing me to do my best and for helping me look on the bright side of every situation. Thank you to my future mother- and father-in-law, Becky and Baba, for their support and care packages. I would also like to thank my girlfriends: Robyn, Julia, Amy, Michelle, and Katie for inspiring me every day. I would especially like to thank my partner, Sam, for standing by me throughout my academic studies. His encouragement to apply to the program, his constant love and support throughout my degree, and his strong work ethic pushed me to complete this thesis. I am excited to see what the future holds for us. Finally, a special thank you to my late grandmother, Phyllis Chapman, for her support and her contagious positivity throughout my academic studies until her final days. She was my biggest cheerleader, and I would not have reached this point without her. ii Table of Contents Abstract ................................................................................................................................ i Acknowledgments............................................................................................................... ii Table of Contents ............................................................................................................... iii List of Tables ..................................................................................................................... vi List of Figures .................................................................................................................. viii List of Appendices ........................................................................................................... xiii List of Symbols ................................................................................................................ xiv Chapter 1 ............................................................................................................................. 1 1 Introduction .................................................................................................................... 1 1.1 General .................................................................................................................... 1 1.2 Goal and Objectives ................................................................................................ 3 1.3 Structure of Thesis .................................................................................................. 4 Chapter 2 ............................................................................................................................. 6 2 Fundamentals of the Present Work ................................................................................ 6 2.1 Fundamental Equations ........................................................................................... 6 2.1.1 Fundamental Equations of Flow ................................................................. 7 2.1.2 Fundamental Equations of Sediment Motion ............................................. 9 2.1.3 Fundamental Equations of Shear Stress .................................................... 12 2.1.4 Fundamental Equations of Bank Erosion ................................................. 13 2.2 Mathematical Modeling ........................................................................................ 17 2.2.1 HEC-RAS ................................................................................................. 17 Chapter 3 ........................................................................................................................... 20 3 Literature Review ......................................................................................................... 20 3.1 Stream Restoration and Channel Design .............................................................. 20 iii 3.2 Mathematical Modeling ........................................................................................ 23 3.3 Summary ............................................................................................................... 26 Chapter 4 ........................................................................................................................... 28 4 Study Area and Methodology ...................................................................................... 28 4.1 Flooding in Southwestern Ontario ........................................................................ 28 4.2 Study Area ............................................................................................................ 30 4.2.1 Previous Alterations to Spencer Creek ..................................................... 34 4.3 Methodology ......................................................................................................... 36 4.3.1 Hydrographs .............................................................................................. 37 4.3.2 Channel Modifications .............................................................................. 39 4.3.3 Simulations ............................................................................................... 40 4.3.4 Model Set-up ............................................................................................. 42 Chapter 5 ........................................................................................................................... 44 5 Results .........................................................................................................................