Recently, the abstract for a paper that I wrote with a fellow PhD student, Jordan Branham, was accepted as a semi-finalist for the ASFPM Foundation’s 9th Annual Collegiate Student Paper Competition. We will be editing the paper for submission in April, and presenting on the topic in May; after which the first, second, and third place entries will be selected. The abstract is included below:
The effects of sea level rise and an increased propensity for major precipitation events caused by global climate change are expected to drive a dramatic reduction in the availability of habitable coastal land and induce population migrations away from particularly vulnerable areas (Allen et al. 2018; R. A. McLeman 2011). However, there is little understanding of how changing risk exposure influences individual decisions to relocate or the thresholds at which these decisions are made (Black, Adger, and Arnell 2013; Bardsley and Hugo 2010). In this paper, we seek to understand how the interaction of different scales of hazard events impact population change over time. To do this, we focus on exposure and vulnerability to flooding events. These events can range from repetitive ‘nuisance’ flooding caused by light weather to storm surges and severe rainfall precipitated by major hurricanes.
We address this research question by examining how minor and major floods between 1990 and 2016 impacted population movements during the same time period in North Carolina. Our study area is home to both coastal and riverine flood hazard areas, affording us the opportunity to tease out the marginal effects of flood vulnerability, exposure to disaster in the form of hurricanes, and the combination of these two factors on population change. Specifically, we use disaster declarations to quantify exposure to major disasters and define a census tract’s vulnerability based on the proportion of buildings within floodplains. Our analysis employs multiple regression with an interaction term in order to assess how our key explanatory variables individually and collectively influence population growth, while controlling for a number of mediating factors such as demographics, economic indicators, geography, and population trajectories.
Our findings suggest that populations have differential responses to environmental risks based on geography, particularly when compounded by joint exposure to both major and repetitive events. More specifically, while coastal communities have experienced significant population growth despite high levels of flood vulnerability, those subareas that are exposed to multiple disasters possess a negative relationship with population growth, suggesting that major disasters can act as focusing events that trigger population shifts (Birkland 1997). Comparatively, it appears that areas subjected to riverine-based flood risk are inclined to population loss in reaction to moderate risk, but less reactive to major events. We expect that these risk-responses will become more pronounced in the era of climate change as both major and minor flood events become more common and out-migration becomes self-supporting. Further, as population loss leads to reduced community resilience, the potential for the rise of non-linear migration exoduses will continue to increase (R. McLeman and Smit 2006; Massey et al. 1993). Therefore, while this study produces important initial findings, it is also presents a methodology that can continue to be used for a more rigorous longitudinal review that will be possible with future Census data.