Date of Award
Master of Science
Geography and Environmental Resources
Levee safety inspections performed in the U.S. under Public-Law 84-99 administered by the U.S. Army Corps of Engineers (USACE) have found ~36% of the participating levee systems have an unacceptable safety rating. This suggests a substantial number of levee systems are not able to keep up with their maintenance. This study seeks to explore if there are differing socioeconomic characteristics between levee systems with acceptable verses unacceptable levee safety ratings to try and assess what characteristics make a system more likely to be sustainable (i.e., possessing an acceptable levee safety rating). In this study, a methodology has been developed using national to regional level socioeconomic data, levee characteristics, and geospatial and statistical analyses to determine if there are differences in socioeconomic factors between levee systems with acceptable verses unacceptable safety ratings. We used this methodology to evaluate 29 levee systems (20 with at least minimally acceptable and 9 with an unacceptable levee safety rating) within the lower Illinois River (LIR) valley. GIS was used to dysameterically map U.S. census and census based block-level socioeconomic data within each of the LIR levee systems. A Principal Components Analysis (PCA) was used to assess which of the socioeconomic variables explained most of the variance between the LIR levee systems. The Mann-Whitney-Wilcoxon U-Test was used to determine if there were statistically significant differences in these socioeconomic variables between levees systems with at least minimally acceptable and an unacceptable levee safety rating. The PCA analysis revealed five components consisting of 19 variables explained 85% of the variance between levee systems. The five components identified were exposure, population, wealth, development, and levee protection characteristics which explained 26.3%, 24.2%, 18.2%, 8.9% and 7.2% of the variance, respectively. The 19 variables which comprised these five components were as follows: levee-protected area, population, percentage non-white, average residential building value, number of residential homes, exposure, percentage of the population between 16 and 64, percentage of the population younger than 16 and older than 64, percentage male, percentage female, percentage white, percentage of the population making more than $40,000, agricultural profit, agricultural profit per acre, average residential building value, percentage of the population making less than $40,000, average per-capita income, and levee-protection level. The Mann-Whitney-Wilcoxon U-Test revealed differences in total population within a levee system, race, average per-capita income, average residential building value, and total population between levee systems with an acceptable verses and unacceptable rating were significant at the α = 0.2 confidence interval. The average per-capita income, percentage of population which is white, average residential building value were all higher on average within levee systems with an unacceptable rating. This seems to suggest populations who inhabit levees with unacceptable safety ratings are white and more wealthy than the communities located within levee systems with at least minimally acceptable ratings. This finding is counter to a large body of research which has shown more vulnerable populations (the poor and poorer minorities) are generally found within areas with higher risk of flooding and other natural hazards. These findings may suggest wealthier floodplain property owners within unacceptable levee systems are foregoing necessary levee maintenance and instead relying on crop insurance and other government programs to pay for future flood damages.
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