Floods of movement
Authors:   , Duijndam Sem Jacobus 
Published: May 2024

Climate change and associated sea-level rise are expected to increase flood risk in many regions, impacting millions of people by impairing human safety and causing damage to agriculture, properties, and critical infrastructure. Migration to safer areas is one way for people to adapt to flood risk and presents an enormous policy challenge given the number of people affected. The main goal of this Thesis is to conduct novel empirical research to better understand the factors driving migration in different contexts. These empirical insights are critical for anticipatory policymaking and management of flood-induced migration, for improving migration forecasting, and for guiding vulnerability and resilience in the face of climate change.

The first research chapter of this dissertation presents a systematic literature review that examines the existing (quantitative) empirical literature on how migration behavior is shaped by flood risk and other sea-level rise-related hazards. It reveals that existing empirical research finds mixed effects for the influence of flooding on migration. Floods sometimes decrease migration in lower-income contexts, possibly due to the financial resource depletion that they cause. The chapter also outlines a comprehensive research agenda for future research on the topic.

A main limitation of existing empirical studies on flood risk and migration is that they focus on the influence of past flood events. Although learning from the past gives us important insights, the dynamics of migration and its drivers are likely to change considerably under increased flood risk from climate change and sea-level rise. Consequently, we miss a solid empirical understanding of migration under increased flood risk. To address this research gap and fulfill the main goal of this dissertation, the second, third, and fourth research chapters of this dissertation present empirical research on drivers of migration under increased flood risk, each contributing in their own way to key research gaps in the literature. In the research presented in these chapters, originally collected household survey data are analyzed from close to 5,000 respondents from six different countries with varying socio-economic contexts worldwide (Vietnam, The Netherlands, Argentina, France, Mozambique and the United States).

Some universal findings on migration under increased flood risk are found in these chapters. First, migration intentions are lower in the lower/middle-income countries studied than in higher-income countries. Second, in all six researched case studies, migration intentions increased considerably under scenarios of increased flood risk. Third, the large majority of respondents, more than 90% in all studied countries, report that they would migrate internally within country borders instead of internationally. Fourth, the implementation of in-situ adaptation measures, another sensible approach for households to protect themselves against increased flood risk, is generally (strongly) associated with lower migration intentions.

The three chapters also provide specific findings. Chapter 2 studies migration under increased flood risk in a context of vulnerable coastal livelihoods in Vietnam showing that social capital as well as past experiences during flooding such as evacuation and receiving aid are strong predictors of migration intentions. Chapter 3 compares drivers of migration and in-situ adaptation in a context of unique extreme flood experience in the Netherlands, showing that in-situ adaptation is mostly related to cognitive factors whereas migration is driven by flood-related emotions. Personal flood experience drives both behaviors. Finally, Chapter 4 provides a unique comparative study on migration under increased flood risk, researching determinants of migration under different flood risk scenarios in Argentina, France, Mozambique, and the United States.

Our results have important implications for policy. Besides others, this Thesis discusses how policymakers should anticipate and plan for increased migration from flood risk, consider supporting in-situ flood adaptation to reduce migration needs, and incorporate that migration behavior is context-specific.