Graduation Year

2023

Document Type

Dissertation

Degree

Ph.D.

Degree Name

Doctor of Philosophy (Ph.D.)

Degree Granting Department

Geography, Environment and Planning

Major Professor

Kamal Alsharif, Ph.D.

Co-Major Professor

Shawn Landry, Ph.D.

Committee Member

Fenda Akiwumi, Ph.D.

Committee Member

James Mihelcic, Ph.D.

Committee Member

Robin Ersing, Ph.D.

Keywords

Spatial Inequities, Temporal Inequities, Hazard Mitigation Policy, GIS, Dasymetric Mapping (Binary Mapping)

Abstract

Floods are recognized as one of the most common and widespread natural hazards in the United States (US). They are responsible for uncompensated losses and damages. Furthermore, evidence suggests flooding inflicts more harm among socially vulnerable groups, incapable of withstanding hazard events, raising environmental equity (EE) and justice (EJ) concerns. Regrettably, with continuing climate change and urbanization, flooding will not subside in the future; instead, the flooding frequency and intensity will increase in many parts of the US, and the trend of disproportionate impacts will continue to rise.

Since Hurricane Katrina, a considerable amount of research has been conducted on examining disparities associated with flood hazards during post-flood situations (i.e., exploring flood experiences across social groups) in the US. However, much less is known about the spatial and temporal inequities during pre-flood situations (i.e., who are at high risk of flooding and whose flood risk changes over time). Hence, this research aimed to add to the growing body of literature by exploring the relationships among floodplains, social vulnerability, and flood risk under the environmental equity framework. The research was carried out in three distinct phases to achieve the goal. These phases were as follows: i) assessing spatial and social inequities in the distribution of flood risks in Federal Emergency Management Agency (FEMA)-designated flood zones of two US coastal cities, Tampa, FL and Houston, TX; ii) exploring whether the proportion of lower-income, minorities, and other socially vulnerable groups living in FEMA designated flood zones had changed over time and how the changes influenced the overall environmental equity situation; and iii) evaluating how local governments addressed flood hazards and related environmental equity concerns in its land use and hazard mitigation planning documents.

To address the first and second phases, both Geographical Information System (GIS) (i.e., dasymetric binary mapping approach) and statistical analyses (i.e., Pearson's correlations coefficients and logistic regression modeling) were performed. In the first phase, spatial and social inequities were examined in the FEMA-designated 100-year or high-risk flood zone of Tampa, FL and Houston, TX - two coastal cities in the US that are highly prone to hurricanes and flooding. This study allowed us to identify the city with the strongest evidence of inequities and explore the other two phases in one city context (i.e., Tampa). A combined approach of quantitative and qualitative analysis was considered to address the third phase of the research.

Three main objectives were accomplished in this research through these three distinctive phases. First, it provided empirical evidence of the disproportionate distribution of socially vulnerable groups in the high-risk flood zone across cities. The findings stressed the importance of adding a diverse range of socially vulnerable indicators to explore the environmental equity implications of flood hazards. Second, change analysis in sociodemographic distribution within the high-risk flood zone enhanced understanding of whose flood risk had changed over time, the degree to which they were vulnerable, and their influence on the overall environmental equity situation. Findings indicated an increase in the proportion of young children and Hispanics in Tampa’s high-risk flood zone. The needs of these vulnerable social groups are often unrecognized in hazard-related policy discourses (i.e., preparedness, response, and recovery). Hence, the implications of these research findings might significantly impact environmental equity research relating to flood hazards and related policy formulations.

Finally, the review and evaluation of selected planning documents, developed by the local government of Tampa, in the third phase yielded essential knowledge regarding the strengths of each planning document in addressing flood hazards and related equity concerns and areas that required improvements. It is expected that the findings of this study will positively influence future planning efforts, resulting in more effective plans, reducing future losses and damages, and helping ensure equitable outcomes.

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