Protection or Peril of Following the Crowd in a Pandemic-Concurrent Flood Evacuation

TL;DR

This study examines how social influence affects evacuation decisions during simultaneous flood and pandemic hazards, revealing complex effects of peer behavior and threat levels on individual choices.

Contribution

It provides novel insights into multi-hazard evacuation decision-making by quantifying social influence impacts during a pandemic flood scenario using survey data.

Findings

Peer influence increases likelihood of evacuating but decreases how to evacuate.

Higher flood threat levels reduce the impact of social influence.

Tailored messaging can modify social influence effects to improve evacuation outcomes.

Abstract

The decisions of whether and how to evacuate during a climate disaster are influenced by a wide range of factors, including sociodemographics, emergency messaging, and social influence. Further complexity is introduced when multiple hazards occur simultaneously, such as a flood evacuation taking place amid a viral pandemic that requires physical distancing. Such multi-hazard events can necessitate a nuanced navigation of competing decision-making strategies wherein a desire to follow peers is weighed against contagion risks. To better understand these nuances, we distributed an online survey during a pandemic surge in July 2020 to 600 individuals in three midwestern and three southern states in the United States with high risk of flooding. In this paper, we estimate a random parameter logit model in both preference space and willingness-to-pay space. Our results show that the directionality and magnitude of the influence of peers' choices of whether and how to evacuate vary widely across respondents. Overall, the decision of whether to evacuate is positively impacted by peer behavior, while the decision of how to evacuate is negatively impacted by peers. Furthermore, an increase in flood threat level lessens the magnitude of these impacts. These findings have important implications for the design of tailored emergency messaging strategies. Specifically, emphasizing or deemphasizing the severity of each threat in a multi-hazard scenario may assist in: (1) encouraging a reprioritization of competing risk perceptions and (2) magnifying or neutralizing the impacts of social influence, thereby (3) nudging evacuation decision-making toward a desired outcome.