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Pluvial Flood Risk Modeling, Assessment, and Management under Evolving Urban Climates and Land Cover

Description

Pluvial flooding is a costly, injurious, and even deadly phenomenon with which cities will always contend. However, cities may reduce their risk of flood exposure by changing historically dominant patterns of development that have removed natural landscape features and reduce the damages that flooding causes by identifying and supporting vulnerable populations. Accomplishing either goal requires the development and application of appropriate frameworks for modeling or recording flood exposure. In this dissertation, I used modeling and surveying methods for assessing pluvial flood exposure in two cities, first in Valdivia, Chile, and then in Hermosillo, México. I open with a summary on pluvial flood risk in the present day and the threat it may pose under changing climates. In the second chapter, I explored how a form of urban ecological infrastructure (UEI), the wetland, is being wielded in Valdivia toward pluvial flood mitigation, and found that wetland daily, seasonal, and interannual changes in wetland surface and soil water storage alter pluvial flood risk in the city. In the third chapter, I used a mixed methodology, including projections of future land cover generated by cellular automata models with inputs from visioning workshops conducted by the Urban Resilience to Extremes Sustainability Research Network (UREx SRN), and found that wetland loss in future land configurations may lead to increased pluvial flood risk. In the fourth chapter, I combined these land cover models from the third chapter with downscaled climate data on precipitation, also generated by the UREx SRN, and found that wetland conservation can help to mitigate the pluvial flood risk posed by changing patterns of rainfall. In the fifth chapter, I applied the Arc-Malstrøm method for pluvial flood assessment in Hermosillo, México, and compared it with the more traditional rational method for flood assessment, and through accompanying surveys found that perception of flood risk is significantly affected by flood dimensions and impacts. This dissertation concludes with a synthesis of pluvial flood risk assessment, suggestions for improvements to modeling, as well as suggestions for future research on pluvial flood risk assessment in cities. This dissertation advances the understanding of the utility of inland wetland UEI in cities under present and future land cover and climate conditions. It also qualifies the utility of common and new pluvial flood risk assessments and offers research directions for future pluvial flood assessments.

ContributorsSauer, Jason R (Author) / Grimm, Nancy B (Thesis advisor) / Chester, Mikhail V (Committee member) / Cook, Elizabeth M (Committee member) / Childers, Daniel L (Committee member) / Eakin, Hallie (Committee member) / Arizona State University (Publisher)

Created2022

Transitioning into Complexity-Driven Resilience Assessments for Urban Systems

Description

Extreme weather events, such as hurricanes, continue to disrupt critical infrastructure like energy grids that provide lifeline services for urban systems, thus making resilience imperative for stakeholders, infrastructure managers, and community leaders to strategize in the face of 21st-century challenges. In Puerto Rico after Hurricane Maria, for example, the energy system took over nine months to recover in parts of the island, thousands of lives were lost, and livelihoods were severely impacted. Urban systems consist of interconnected human networks and physical infrastructure, and the subsequent complexity that is increasingly difficult to make sense of toward resilience enhancing efforts. While the resilience paradigm has continued to progress among and between several disciplinary fields, such as social science and engineering, an ongoing challenge is integrating social and technical approaches for resilience research. Misaligned or siloed perspectives can lead to misinformative and inadequate strategies that undercut inherent capacities or ultimately result in maladaptive infrastructure, social hardship, and sunken investments. This dissertation contributes toward integrating the social and technical resilience domains and transitioning established disaster resilience assessments into complexity perspectives by asking the overarching question: How can a multiplicity of resilience assessments be integrated by geographic and network mapping approaches to better capture the complexity of urban systems, using Hurricane Maria in Puerto Rico as a case study? The first chapter demonstrates how social metrics can be used in a socio-technical network modeling framework for a large-scale electrical system, presents a novel framing of social hardship due to disasters, and proposes a method for developing a social hardship metric using a treatment-effect approach. A second chapter presents a conceptual analysis of disaster resilience indicators from a complexity perspective and links socio-ecological systems resilience principles to tenets of complexity. A third chapter presents a novel methodology for integrating social complexity with performance-based metrics by leveraging distributed ethnographies and a thick mapping approach. Lastly, a concluding chapter synthesizes the previous chapters to discuss a broad framing for socio-technical resilience assessments, the role of space and place as anchors for multiple framings of a complex system, caveats given ongoing developments in Puerto Rico, and implications for collaborative resilience research.

ContributorsCarvalhaes, Thomaz (Author) / Chester, Mikhail V (Thesis advisor) / Reddy, Agami T (Thesis advisor) / Allenby, Braden R (Committee member) / Arizona State University (Publisher)

Created2021

Urban Heat and Transportation: Human Exposure and Infrastructure

Description

Environmental heat is a growing concern in cities as a consequence of rapid urbanization and climate change, threatening human health and urban vitality. The transportation system is naturally embedded in the issue of urban heat and human heat exposure. Research has established how heat poses a threat to urban inhabitants and how urban infrastructure design can lead to increased urban heat. Yet there are gaps in understanding how urban communities accumulate heat exposure, and how significantly the urban transportation system influences or exacerbates the many issues of urban heat. This dissertation focuses on advancing the understanding of how modern urban transportation influences urban heat and human heat exposure through three research objectives: 1) Investigate how human activity results in different outdoor heat exposure; 2) Quantify the growth and extent of urban parking infrastructure; and 3) Model and analyze how pavements and vehicles contribute to urban heat.

In the urban US, traveling outdoors (e.g. biking or walking) is the most frequent activity to cause heat exposure during hot periods. However, outdoor travel durations are often very short, and other longer activities such as outdoor housework and recreation contribute more to cumulative urban heat exposure. In Phoenix, parking and roadway pavement infrastructure contributes significantly to the urban heat balance, especially during summer afternoons, and vehicles only contribute significantly in local areas with high density rush hour vehicle travel. Future development of urban areas (especially those with concerns of extreme heat) should focus on ensuring access and mobility for its inhabitants without sacrificing thermal comfort. This may require urban redesign of transportation systems to be less auto-centric, but without clear pathways to mitigating impacts of urban heat, it may be difficult to promote transitions to travel modes that inherently necessitate heat exposure. Transportation planners and engineers need to be cognizant of the pathways to increased urban heat and human heat exposure when planning and designing urban transportation systems.

ContributorsHoehne, Christopher Glenn (Author) / Chester, Mikhail V (Thesis advisor) / Hondula, David M. (Committee member) / Sailor, David (Committee member) / Pendyala, Ram M. (Committee member) / Arizona State University (Publisher)

Created2019