Dissertation & Thesis Defenses

Lidia Roy
MS - Thesis Defense
Thursday, October 29, 2026
11:00 AM in person and Zoom
ELA 344

Advisor
Dr. Su Han

Committee Members:
Dr. Ben Zhan
Dr. Nate Currit

Abstract:
The extent to which at-risk individuals can obtain pre-exposure prophylaxis (PrEP) depends heavily on its availability, particularly the balance between service supply and population demand among vulnerable populations in U.S. metropolitan areas. Conventional accessibility measures based on general population demand may overlook differences in access for specific populations, including men who have sex with men (MSM). This study examines spatial inequalities in PrEP accessibility across metropolitan Atlanta, Georgia, and evaluates how population demand definitions influence accessibility estimates in relation to HIV prevalence and socioeconomic conditions.

Using PrEP provider locations, road-network driving times, and population estimates for residents aged 16 years and older, the study applies a Gaussian Enhanced Two-Step Floating Catchment Area (E2SFCA) model to measure potential geographic accessibility. At the ZIP Code Tabulation Area (ZCTA) level, county-level MSM population estimates were spatially allocated to ZCTAs to provide an alternative population demand measure for the accessibility model. Sensitivity analyses examined the effects of different distance-decay parameters, while global and bivariate spatial autocorrelation analyses evaluated geographic clustering and spatial relationships among HIV prevalence, poverty, and modeled PrEP accessibility.

Results reveal spatial inequalities in PrEP accessibility across the Atlanta metropolitan area. HIV prevalence, poverty, and general-population-based PrEP accessibility each exhibited significant spatial clustering. HIV prevalence showed a positive spatial association with neighboring PrEP accessibility (bivariate Moran's I = 0.581, p = 0.001), indicating that higher HIV prevalence did not consistently coincide with lower modeled accessibility. Estimated MSM rates were positively correlated with HIV prevalence (Pearson's r = 0.694, p < 0.001, n = 183). However, general-population-based and MSM-based accessibility rankings showed no statistically significant correlation among ZCTAs with valid observations for both measures (Spearman's ρ = −0.051, p = 0.644, n = 84), suggesting that population demand definitions can produce substantially different representations of potential access.

These findings demonstrate that spatial inequalities in PrEP accessibility are shaped by geographic variation in service supply and population demand, while their relationships with HIV prevalence and socioeconomic conditions are more complex than a simple pattern of higher need and lower access. Incorporating estimated MSM population provides a population-specific perspective on potential accessibility, although incomplete geographic coverage limits broader generalization. The study highlights the importance of considering population demand, HIV burden, and socioeconomic context together when evaluating geographic accessibility to PrEP services and offers insights for geographically informed HIV prevention planning in metropolitan Atlanta.

Wesley Kimeli
MS - Thesis Defense
Thursday, November 5, 2026
2:00 PM in person and Zoom
ELA 344

Advisor
Dr. Samantha Krause

Committee Members:
Dr. Nathan Currit
Dr. Nandy Li

Abstract:
This study examines wetland change trajectories (1985-2025) and their correlation with land surface temperature (LST) in Nandi County, Kenya. Wetlands cover about 10% of Africa, but food production and economic pressures have driven wetland encroachment and forest loss. Despite their conservation importance, comprehensive maps of small wetlands, distribution, size, and changing status remain scarce across Africa. Landsat data were analyzed in Google Earth Engine (GEE) using a Random Forest algorithm to assess land use/land cover change (LULC). Wetland trajectory exhibited notable temporal fluctuations over the study period. Wetland area expanded by 50.3% between 1985 and 1995, then decreased by 39.3% by 2002 and by an additional 11.9% by 2015. Wetland extent subsequently recovered, increasing by 34.8% by 2025. Correspondingly, LST varied across the study years, suggesting a potential correlation between wetland cover and changes in surface temperature.  Further, statistical analyses were used to assess the relationships among these factors in the study area. This study adds to the growing literature on wetland dynamics and land use/land cover (LULC) in Kenya, particularly the use of remote sensing for environmental monitoring. It establishes that wetland degradation in Nandi County has not followed a linear trajectory. Because wetlands are declining worldwide, studies like this provide valuable local analyses of a global problem, and these findings may help raise awareness of the need for wetland conservation.

Greg Turner
Dissertation Defense
Friday, November 6, 2026
9:30 AM in person and Zoom
ELA 344

Advisor
Dr. Eric Sarmiento

Committee Members:
Dr. Ronald Hagelman
Dr. Colleen Myles
Dr. Antonio Petrov, Architecture and Planning, UTSA

Abstract:
This dissertation traces the evolution of the Christian church bell tower through modern Texas history, presenting it as an artifact whose functionality and presence has been threatened by industrialization and urbanization.  In response, the bell tower’s former material and semiotic unity has dissolved, to be replaced by an array of devices that target messages of sacred Christian place to the variety of peoples, both immigrant and native, who populate Texas.  These messages, now conveyed not only in the iconic tower form but by a wide variety of other object types, have facilitated the transport of people and Christian ideas across and within the state since independence in 1836.  Moreover, their physical aggregation in space, their capacity to induce human movement, and their messaging apparatuses all cohere to transform bell towers into something that transcends their individual materiality and meaning—an infrastructure.

Considering bell towers within DeLanda’s conception of assemblage, I draw from an array of literature and from analysis of photographs of over five thousand Texas churches to propose a conceptual framework of ideological eras.  This notion emerged through a methodological process called layered analysis that took the quantifiable data represented in the photographs and mined them qualitatively to discern contextual meanings.  The framework synthesizes physical attributes such as age, placement, monumentality, and verticality with religious belief and practice and connects these with expressions of faith and culture.  This assemblage of material and message endows bell towers with their infrastructural capacity.

Mason Miller
MS - Thesis Defense
Monday, November 9, 2026
12:00 PM
ELA 344 & Zoom

Advisor
Dr. Samantha Krause

Committee Members:
Dr. Nathan Currit
Dr. Edwin Chow

Abstract:
Acequias are New Mexico’s community-based water sharing systems whose physical form is determined by cyclical adaptation. These landscape modifications are rooted in both the Indigenous practices and perspectives as well as Iberian-colonial legal practices. This study compares traditionally maintained earthen channels in the Española Valley and concrete-lined systems in the Mesilla Valley by asking whether acequia alignments can be separated from natural streams using DEM-derived terrain and hydrographic surfaces, how terrain and climate relate to ecological functionality as measured by enhanced vegetation index, and whether acequias leave measurable microclimate signatures.

Logistic regression models were able to separate acequia channel segments form natural streams with high discrimination (cross-validated AUC of 0.895 in the Española Valley and 0.980 in the Mesilla Valley). Thirty-year trend analysis of monthly watershed precipitation and mean air temperature indicate warming of nearly 1°C in both regions as well as statistically significant decline of growing-season precipitation in the Española Valley. Microclimate trends of land surface temperature, enhanced vegetation index, and actual evapotranspiration identified that acequias within the Española Valley display patterns like riparian buffers while those in the Mesilla Valley resemble urban heat islands. Generalized additive models of 2000 to 2020 enhanced vegetation index identified that land surface temperature was the strongest predictor, with minor effects of slope in the Española Valley where vegetative health declined rapidly above 9 percent. These findings indicate construction material and the structural geometry of acequias shape their terrain and ecological signatures. Further, the terrain-based GIS processes utilized could support state and federal managers and policymakers in mapping and prioritizing channel segments for maintenance and preservation.

Josh Knolla
PhD - Dissertation Defense
Tuesday, November 10, 2026
10:00 AM in person and Zoom
ELA 344

Advisor
Dr. Denise Blanchard

Committee Members:
Dr. Nate Currit
Dr. Edwin Chow
Dr. Todd Moore, Department of Geosciences, Middle Tennesseet

Abstract:
Drought and flood are two of the most widely observed hazards to humans and the environment. Although they sit at opposite ends of the precipitation spectrum, deficit and excess, they are rarely examined as one compound hazard. This hazard type, Drought–Flood Abrupt Alternation (DFAA), has drawn growing interest in hazards literature as the climate becomes more variable, but research remains geographically limited. This research identifies DFAA and explores its possible drivers in the flash-flood-prone Guadalupe River Basin, Texas, from 1981 to 2025. Three questions guide the work: How does dataset selection impact DFAA identification? What are the temporal and spatial characteristics of DFAA events in the Guadalupe River Basin? What large-scale mechanisms influence the variance of DFAA in this region? Events were identified from daily 800 m PRISM precipitation with a standardized weighted precipitation index and grouped into storm-scale episodes, with Daymet and 15 in-basin gauges as corroboration. Analyses then measured the variance, frequency, intensity, and size of activity from year to year and season to season. Finally, activity was classified as dormant, normal, or active to test the influence of teleconnection states. Drought-to-flood transitions outnumbered flood-to-drought transitions three to one, and activity rose in every dataset, although the size of the increase differs, largely because PRISM added radar in 2002. In contrast, the datasets agree closely on which years are active. DFAA activity is best characterized by its year-to-year variance, far beyond chance in every dataset, and by an absence of memory between years. No strong teleconnection effects were detected, though the design could detect only strong effects; results instead point to storm-scale controls. Future work should ask whether this volatility belongs to the hazard or to the basin, and test what smaller-scale atmospheric conditions predict activity levels. DFAA is a real, recurring hazard in this basin that should be planned for and managed.

Emily Rhodes
Dissertation Defense
Wednesday, November 11, 2026
12:30 AM - 3:00 PM
ELA 344

Advisor
Dr. Eric Sarmiento

Committee Members:
Dr. Ronald Hagelman
Dr. Jennifer Devine
Dr. Monica White, Department of Community & Environmental Sociology
Dr. Rosie Ray, Urban Policy & Planning

Abstract:
This project examines how residents of the Eastside, a constellation of predominantly Black neighborhoods in Oklahoma City and beyond, have employed practices of collective agency and community resilience and self-reliance to create and maintain plots, sites of embodied sovereignty, from pre-statehood to today. Oklahoma City’s history – from one of the last frontiers in the United States, to segregation and Jim Crow, to Urban Renewal, and most recently cosmopolitan ‘creative’ redevelopment – has provided Black residents opportunities for autonomy and self-reliance in the face of systemic marginalization. The research traces how Black in-migration from the time of the Oklahoma frontier brought rural practices of growing and sharing food that have sustained the community for over a century, including when the community faced the closure of the only full-service grocery store on the Eastside in 2019. The story of Oklahoma City’s Eastside is one of persistent struggle and resilient worldmaking, centered on the politics of food. From the aspirations of Black settlers seeking refuge and self-determination in the Land Runs to the efforts of urban farmers, the cultivation of land has served as a radical act of worldmaking. Food insecurity on the Eastside, I further demonstrate, was produced through the municipal government’s and developers’ long-standing practices of segregation, disinvestment, urban renewal, and uneven development. Each of these moments carried its own vocabulary, yet each located the problem in Black neighborhoods and their residents. In 2021, through public-private partnerships, the Eastside welcomed two new grocery stores and the first new development in the community in over twenty years. How this development came about and its possible impacts, particularly concerns over gentrification, are interrogated. A GIS-based analysis shows that gentrification has occurred in many diverse areas of Oklahoma City, including parts of the Eastside. Given that Oklahoma City now brands itself as the Modern Frontier, diverse and inclusive, these discourses and their impacts must be understood. The Modern Frontier brand relies on the restaurants that have emerged as evidence of a renaissance, with Black restaurants coded as heritage, innovation, or both, and with Black history rendered in the past tense. Finally, how the frontier has held different meanings for different groups over time is also investigated. Today, the frontier enables cosmopolitanism and diversity where it can be marketed. Yet the plots and practices of collective agency and community resilience created and maintained by Eastsiders through the long history of racialized planning are the grounds on which residents now contest erasure or commodification through growing and sharing food and asserting belonging.

Mogahid Hussein
Monday, October 5, 2026
12 PM, Zoom

Advisor
Dr. Ronald Hagelman

Committee Members:
Dr. Alberto Giordano
Dr. Edwin Chow
Dr. Brendan Lavy, Environmental Sciences, TCU
Dr. Brendan Lavy, Environmental Sciences, TCU

Abstract:
Social vulnerability to hazards is unevenly distributed across space and changes over time, but most studies capture it at a single moment. That approach makes it hard to tell which places are experiencing lasting disadvantage and which are only temporarily strained. It also leaves open the question of whether the places that federal agencies flag as high-risk are the same places where socially vulnerable populations actually live. This dissertation addresses both gaps in the Austin–San Antonio metropolitan corridor, a 13-county region containing 807 census tracts and more than 5.2 million residents.

Using American Community Survey 5-year estimates from 2009, 2014, 2019, and 2024 harmonized to 2010 tract boundaries, the study builds a custom Social Vulnerability Index (SVI) from 12 indicators. Vulnerability scores are standardized across all 3,228 tract-year observations at once, so a score in 2009 is directly comparable to a score in 2024. Three questions guide the analysis: how vulnerability was distributed across the corridor over the 15-year period, how stable high-vulnerability clusters were across the four time points, and whether high-vulnerability tracts overlap with tracts of elevated FEMA-modeled Expected Annual Loss.

Corridor-wide vulnerability leveled out slightly over time, but the two metropolitan areas diverged sharply. San Antonio contains 90 of the 98 tracts that remained highly vulnerable across the full study period, concentrated on the West, South, and inner-East Sides of Bexar County. Austin contains 78 of the 92 tracts that remained persistently low in vulnerability and shows inner-city vulnerability declining while outer counties rose, a pattern consistent with displacement. Of 188 SVI hot spot tracts identified through Getis-Ord Gi* analysis, only 2 also register as Expected Annual Loss hot spots. Federal hazard-loss modeling is dominated by property values, which are systematically higher in less vulnerable places.

Findings show that federal hazard-loss modeling and persistent social vulnerability occupy different geographies at the tract scale, with implications for how equity-informed mitigation planning uses these tools.

Dustin Sanchez
Friday, September 18, 2026
9:30 AM

Abstract:
Global wine production is on the verge of calamitous disruption caused by global warming-induced climate change. In many regions, the interlocking forces of political and military conflict further intensify the effects of climate hazards by disrupting established systems and deepening vulnerabilities. The purpose of this study is to investigate the structural violence, the systemic, avoidable harm caused by political, economic, or social structures that restrict access to resources or power, and territorial transformation driven by conflict and vulnerability for viticulturalists within the fragile-state dynamics in the Dukagjin (Metohija) wine region of Kosovo. This project explores how historical marginalization of Albanian identity, in particular within late Yugoslavia, structured conditions that produced socio-ecological vulnerability with a cross-case study mixed-methods approach. By examining Kosovo viticulture, a climate-vulnerable agricultural industry within a geopolitically fragile region, this study explores how structural violence during territorial transformation influences hazard vulnerability. When power is consolidated into a functional political state where outcomes appear linear, it can be understood as enhancing vulnerability. When power becomes asymmetrical, and exists in parallels, it can actively produce vulnerability through structural violence. The viticulturalists of Kosovo are trapped in a Serbian geopolitical economic system blocked by profit-motivated capitalists employing historic structures to turn farmers into bounded serfs with a cartel-controlled oligopsony. These market conditions were originally part of a hybridized-war against Albanians beginning in the late 1980s, which devolved into a kinetic war of ethnic cleansing. While the ethnic cleansing was stopped by western intervention, the hybridized-war continues. This framework enables a future-oriented analysis of how history shapes present vulnerabilities and limits the potential for equitable adaptabilities.