Avoiding or mitigating flooding: Bottom-up drivers of urban resilience to climate change in the USA

Abstract

Coastal areas around the world are urbanizing rapidly, despite the threat of sea level rise and intensifying floods. Such development places an increasing number of people and capital at risk, which calls for public flood management as well as household level adaptation measures that reduce social vulnerability to flooding and climate change. This study explores several private adaptation responses to flood risk, that are driven by various behavioral triggers. We conduct a survey among households in hazard-prone areas in eight coastal states in the USA, of which, some have recently experienced major flooding. While numerous empirical studies have investigated household-level flood damage mitigation, little attention has been given to examining the decision to retreat from flood zones. We examine what behavioral motives drive the choices for flood damage mitigation and relocation separately among property buyers and sellers. Hence, we focus on the drivers that shape demand for future development in flood-prone cities. We find that households' choices to retreat from or to avoid flood zones (1) are highly sensitive to information that provokes people's feelings of fear, and (2) rely on hazardous events to trigger a protective action, which ideally would take place well before these events occur. We highlight that major flooding may cause a potential risk of large-scale outmigration and demographic changes in floodprone areas, putting more low-income households at risk. Therefore, coordinated policies that integrate bottomup drivers of individual climate adaptation are needed to increase urban resilience to floods.

Repetitive floods intensify outmigration and climate gentrification in coastal cities

“…The datasets also contain 1:100 and 1:500 flood zones, as designated by the FEMA that offers flood maps based on location and elevation of the property [44]. To instantiate agents behavioural rules we use the household survey conducted separately among buyers and sellers (total N=1040) in January-February 2017 in eight coastal states in the USA, of which some have recently experienced major flooding [45]. At the core we model location choices of individual households and their perceptions towards flood risk, which may affect their behaviour in the housing market, as illustrated in figures 1 and 2.…”

“…However, when experiencing a hazard event behavioural biases alter individual choices. Namely, households' attitude towards flood risk may inhibit them from buying a property in a flood zone (figure 1), as elicited from the survey data [45].…”

“…If house receive no bids, a seller would gradually reduce the ask price. Those sellers who used to reside within a flood zone will more likely search for a new house in a safe location when they have experienced a flood (figure 2) [45].…”

“…Further, we simulate how people update their risk perceptions and their preferences for living in a flood zone after the occurrence of a major flood, which is grounded in theory and empirical observations of household-level preferences and behaviour in response to floods [45]. This is modelled by altering the posterior probability that buyers will avoid properties in the flood zone, or that households abandon the flood zone, conditional on their level of fear towards flooding, their experience with flooding and whether their property got damaged from floods.…”

“…The price recovery is a result of newcomers entering the market from outside who have not yet experienced local floods. These people are generally less risk-aware than those who have experience with flooding and damage to property [45] and see an investment opportunity in the temporarily low-valued properties in the hazard zones. As a result of market sorting, this group of risk-unaware buyers generally have a lower income than households who lived there before the flood.…”