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Topic

Classifying Flood Disruptions to Urban Transport: A Spatio-Temporal Lens Using Coupled Hydrodynamic–Traffic Models

Department of Mechanical Engineering

Date & location

• Wednesday, November 26, 2025

• 10:00 A.M.

• Virtual Defence

Reviewers

Supervisory Committee

• Dr. Caterina Valeo, Department of Mechanical Engineering, ӣ��Ӱ�� (Supervisor)

• Dr. Yang Shi, Department of Mechanical Engineering, UVic (Member)

• Dr. Jianxun He, Department of Mechanical Engineering, UVic (Member)

• Dr. Rishi Gupta, Department of Civil Engineering, UVic (Outside Member) 

External Examiner

• Dr. Zoe Li, Department of Civil Engineering, McMaster University 

Chair of Oral Examination

• Dr. Trevor Lantz, School of Environmental Studies, UVic

   

Abstract

The transportation sector is an essential pillar of both economic prosperity and social well-being, and its functionality and resilience are increasingly challenged by the impacts of climate change. Transportation systems are directly and indirectly affected by extreme climatic scenarios on a range of spatial and temporal scales, with floods and heavy rainfall being the most critical hazards. In recent decades, urban regions around the globe have experienced notable increases in flood intensity and frequency. Such extreme events can significantly strain transportation networks in the short term through congestion, delays, and trip cancellations, while also producing medium- and long-term impacts associated with infrastructure damage, system recovery, and cascading disruptions that reverberate across economic and social systems. 

The present research reviews and advances the understanding of how flooding affects transportation networks across different timescales. Flood effects are classified according to their connection to both the type of flooding and the nature of impact whether direct, indirect, or cascading on the transportation system. Existing literature demonstrates that most studies concentrate on assessing direct and tangible impacts, typically emphasizing short- and medium term resilience at smaller spatial scales. By contrast, there is relatively limited attention given to indirect or intangible consequences, or to longer-term temporal horizons where recovery, adaptation, and broader socio-economic feedback become more apparent. This imbalance highlights a gap in both methodological approaches and conceptual frameworks, particularly when considering how multiple stressors such as rainfall and flooding interact to magnify disruptions.

To address these gaps, this dissertation applies a combined hydraulic and traffic modeling frameworks to capture the compounded effects of rainfall and flooding on transportation. The 2013 flood in the City of Calgary is selected as the case study considering its severity, dual riverine sources (the Bow and Elbow Rivers), and its well-documented impacts on both urban systems and transportation infrastructure. A hydraulic model (HEC-RAS®) is used to simulate flood dynamics, while a traffic microsimulation model (SUMO®) is employed to replicate traffic conditions under four distinct scenarios: dry/no rainfall baseline, rainfall, flooding with and without rainfall, and post-flooding conditions. Both static and dynamic routing simulations are conducted to compare traveler responses and system performance under varying levels of disruption and adaptability. A new penalty model is proposed that deals with the limitations and enhances the realism of SUMO simulations leading to better quantification of indirect impacts. 

Results at the overall network level demonstrate clear degradation of performance across all flood related scenarios. Compared to the dry baseline, average delay increased by 15 - 40%, average distance traveled grew by 10 - 45%, and the proportion of lost or uninserted vehicles rose by 10 - 55%, while average speed decreased by 2 - 17%. The rainfall-only scenarios also contributed significantly to these degradations, further exacerbating network inefficiencies by 2 - 17% depending on the performance metric. These findings underscore the importance of considering not only floodwater but also antecedent rainfall conditions when evaluating transportation resilience, as rainfall effects can serve as both precursors to flooding and independent stressors on urban networks. It also demonstrates that indirect impacts can be quantified appropriately when using traffic micro-simulation models.

 Beyond aggregated network performance, localized spatial analyses provide further insights. Origin-based assessments reveal zones of vulnerability where the network is less capable of inserting and processing trips, thereby identifying spatial points of systemic weakness. Destination-based assessments, by contrast, highlight the consequences of flooding for accessibility, congestion, and serviceability, demonstrating how certain areas become isolated or disproportionately burdened by disrupted flows. Together, the origin- and destination-based perspectives capture the intertwined nature of vulnerability and congestion, and illustrate how direct, indirect, and cascading impacts manifest unevenly across space and time.

 Overall, this research contributes to a more comprehensive understanding of how flooding and rainfall affect transportation networks, not through the development of new methodologies, but by applying well-established modeling tools in an integrated manner to generate empirical evidence, comparative analyses, and interpretive insights. The dissertation advances knowledge by documenting how compound rainfall and flood hazards alter both network-level performance and localized spatial dynamics, highlighting the significance of direct, indirect, and cascading impacts, and offering evidence-based perspectives that can inform urban planning, disaster preparedness, and infrastructure adaptation under a changing climate.