Exploring the Intention–Behavior Relationship in Flood Adaptation Using Longitudinal Data

Insights into factors motivating individual adaptation are needed to reduce flood damage, especially in lower-income countries. According to key behavioral theories, adaptation intention leads to behavior and is, therefore, often used as a proxy for implementation. Empirical studies, however, report substantial intention‒behavior gaps (i.e., the percentage of intended actions unrealized) and limited predictive power of models built on these theories. The literature suggests that intention strength, which captures levels of commitment, could better predict behavior but has not been tested in the flood risk domain. Moreover, several predictors might influence intention and actual behavior differently or might even influence behavior independently. Studying the intention‒behavior relationship could thus help increase the theories' predictive power. Investigating the intention‒behavior relationship is challenging due to the lack of longitudinal surveys that capture behavior over time. Here, we deploy intention strength in a two-wave longitudinal survey among 401 randomly selected respondents from Vietnam (95% retention rate) to examine the intention‒behavior relationship in preparing devices and retrofitting homes against flooding. We find that > 90% of intended adaptive actions indicated by respondents in Wave 1 went unrealized within 6 months. Intention strength seems unimportant for preparing devices, whereas the strongest intention significantly correlates with higher implementation of retrofitting homes. Studies using intention as a proxy for behavior could, therefore, consider intention strength instead. We also find various factors significantly motivating behavior but not intention, including financial capacity, experiencing large floods regularly, and housing situation. Policymakers, therefore, should focus more on these factors when considering adaptation strategies. Future research in other settings could contextualize the adjustment to behavioral theories.