Floods appear in many of the world's oldest stories (i.e. Noah and the Arc in the Abrahamic religions, Manu in Hinduism, and the Gun-Yu myth in Chinese mythology). When observed historically, they often have an element of mysticism about them, symbolizing eradication and rebirth. In the present, however, there is little that is mystical about the devastation brought on by floods as they cause more destruction annually than any other hazard. With much of the modern development taking place along the coast or near riverways, assets and livelihoods are increasingly concentrated in exposed areas. By-products of climate change such as sea level rise and extreme precipitation events increasingly devastate these regions; with the projection that the risk of floods will continue to increase in the future. Top-down, government-led adaptation to floods on its own cannot contend with growing risk; rendering household participation essential. Governments, risk modelers, scientists, and other interest groups (i.e. NGOs) need a solid understanding of household behavior in order to formulate strategies and engage stakeholders across scales to address climate-induced risks. This dissertation devotes its attention to better understanding households' perceptions, intentions, and behavioral drivers and their dynamics, concerning floods in various social, geographical, cultural, and environmental contexts. More concretely, the principal research objective of this dissertation is: To progress toward an understanding of how households perceive, are affected by, and adapt to floods in various contexts over time. Following a comprehensive review and analysis of prior empirical research on household flood adaptation, this dissertation presents the analysis of a panel survey carried out between 2020-2021 aimed at collecting data to tackle the aforementioned objective. Focusing on large urban centers in the United States, China, Indonesia, and the Netherlands I use various statistical techniques and methods to analyze the survey data and study a range of aspects from household perceptions as they concern floods and climate change, to reported adaptation behavior. The survey solicits information on 18 adaptation measures that range from inexpensive, actions that do not require considerable effort (i.e. having an emergency preparedness kit, emergency coordination with one's neighbor, etc.), to costly measures that require a substantial time investment (i.e. elevating one's home, waterproofing one's windows, etc.) In analyzing how household adaptation decisions are influenced, depending on the extit{type} of measure and the context in which the household resides, this dissertation offers insight into which socio-behavioral drivers and barriers of household adaptation are generic and those which may vary depending on the institutional and environmental conditions. A household's perceived ability to cope, and the emotion, ``worry,'' plays a substantial role in driving household adaptation intention. In contrast, the financially calculated risk-based drivers: the perceived probability of a flood happening and the perceived damage should a flood occur, generally have a more subdued effect on household adaptation intentions. This is related to the fact that not all households have sufficient capacity or awareness to subjectively assess the probability and damage of a potential flood. Individual risk-uncertainty - a trait more frequently found in populations historically more vulnerable to floods (i.e. women and lower educated) has a large detrimental effect on households' intention to pursue flood adaptation measures. While internal perceptions are critical to consider, external factors can have an equally potent role in affecting household adaptation behavior. I examine the effect of context at multiple scales in this dissertation, assessing the role of social expectations, perceptions of government measures, and national culture on household adaptation decisions. Households use their observations of what others (i.e. their social network, the government) are doing with respect to flood adaptation, to inform their decisions. The degree to which both external and internal factors influence household adaptation decisions can differ based on the cultural and geographical context. Various factors have a weaker or stronger influence and at times even the opposite effect on adaptation behavior, depending on where the household resides. While internal and external perceptions are requisite considerations in understanding household behavior, it is likewise crucial to account for experiences and the co-benefits of various household adaptive actions. The effects of prior flood experiences and the benefits of taking adaptations together are additional key considerations when studying household flood adaptation, due to the economic benefits that can arise from undertaking measures together. Furthermore, prior experience with floods can motivate adaptation behavior, but substantial financial damage from a flood impedes a household's adaptation intention; as their focus is on recovery, not adapting. The findings in this dissertation are of use to scientists, modelers, risk specialists, and policymakers; whether they are designing models, a communication strategy, or a policy aimed at encouraging household action. With the effects of climate change increasingly affecting communities across the globe, households are having to contend with hazards that are more extreme and frequent than in the living memory of humanity. Unless immediate action is taken across scales, the harrowing effects of climate change are expected to increasingly threaten extensive populations globally. This dissertation provides insights into how households think, perceive, behave, and learn over time concerning one of the most deadly and damaging hazards: floods. @en

Despite the growing calls to integrate realistic human behavior in sustainability science models, the representative rational agent prevails. This is especially problematic for climate change adaptation that relies on actions at various scales: from governments to individuals. Empirical evidence on individual adaptation to climate-induced hazards reveals diverse behavioral and social factors affecting economic considerations. Yet, implications of replacing the rational optimizer by realistic human behavior in nature-society systems models are poorly understood. Using an innovative evolutionary economic agent-based model we explore different framings regarding household adaptation behavior to floods, leveraging on behavioral data from a household survey in Miami, USA. We find that a representative rational agent significantly overestimates household adaptation diffusion and underestimates damages compared to boundedly rational behavior revealed from our survey. This "adaptation deficit" exhibited by a population of empirically informed agents is explained primarily by diverse "soft" adaptation constraints-awareness, social influences-rather than heterogeneity in financial constraints. Besides initial inequality disproportionally impacting low/medium adaptive capacity households post-flood, our findings suggest that even under a nearly complete adaptation diffusion, adaptation benefits are uneven, with late or less-efficient actions locking households to a path of higher damages, further exacerbating inequalities. Our exploratory modeling reveals that behavioral assumptions shape the uncertainty of physical factors, like exposure and objective effectiveness of flood-proofing measures, traditionally considered crucial in risk assessments. This unique combination of methods facilitates the assessment of cumulative and distributional effects of boundedly rational behavior essential for designing tailored climate adaptation policies, and for equitable sustainability transitions in general.

@en

Climate change intensifies the likelihood of extreme flood events worldwide, amplifying the potential for compound flooding. This evolving scenario represents an escalating risk, emphasizing the urgent need for comprehensive climate change adaptation strategies across society. Vital to effective response are models that evaluate damages, costs, and benefits of adaptation strategies, encompassing non-linearities and feedback between anthropogenic and natural systems. While flood risk modeling has progressed, limitations endure, including inadequate stakeholder representation and indirect risks such as business interruption and diminished tax revenues. To address these gaps, we propose an innovative version of the Climate-economy Regional Agent-Based model that integrates a dynamic, rapidly expanding agglomeration economy populated by interacting households and firms with extreme flood events. Through this approach, feedback loops and cascading effects generated by flood shocks are delineated within a socio-economic system of boundedly-rational agents. By leveraging extensive behavioral data, our model incorporates a risk layering strategy encompassing bottom-up and top-down adaptation, spanning individual risk reduction to insurance. Calibrated to resemble a research-rich coastal megacity in China, our model demonstrates how synergistic adaptation actions at all levels effectively combat the mounting climate threat. Crucially, the integration of localized risk management with top-down approaches offers explicit avenues to address both direct and indirect risks, providing significant insights for constructing climate-resilient societies.

@en

As climate change increases the probability and severity of natural hazards, the need for coordinated adaptation at all levels of society intensifies. Governmental-level adaptation measures are essential, but insufficient in the face of growing risks, necessitating complementary action from households. Apprehending the drivers of household adaptation is critical if governments are to stimulate protective behavior effectively. While past work has focused on the behavioral drivers of household adaptation, little attention has been paid to understanding the relationships between adaptation measures themselves—both previously undergone and additionally (planned) intended adaptation(s). Using survey data (N = 4,688) from four countries—the United States, China, Indonesia, and the Netherlands—we utilize protection motivation theory to account for the behavioral drivers of household adaptation to the most devastating climate-driven hazard: flooding. We analyze how past and additionally intended adaptations involving structural modification to one's home affect household behavior. We find that both prior adaptations and additionally intended adaptation have a positive effect on intending a specific adaptation. Further, we note that once links between adaptations are accounted for, the effect that worry has on motivating specific actions, substantially lessens. This suggests that while threat appraisal is important in initially determining if households intend to adapt, it is households' adaptive capacity that determines how. Our analysis reveals that household structural modifications may be nonmarginal. This could indicate that past action and intention to pursue one action trigger intentions for other adaptations, a finding with implications for estimating the speed and scope of household adaptation diffusion.@en

Risk assessments are key for the effective management of potential environmental threats. Across probabilistic phenomena, climate change is an exemplar of paramount uncertainties. These uncertainties have been embraced in supporting governments’ decisions; yet receive scarce attention when studying individual behavior. Analyzing a survey conducted in the USA, China, Indonesia, and the Netherlands (N=6242), we explore socio-economic, psychological, and behavioral differences between individuals who can subjectively assess risks, and those who are risk-uncertain. We find that risk-uncertain individuals are more likely to belong to societal subgroups classically considered as vulnerable, and have reduced capacities and intentions to adapt to hazards—specifically floods. The distinctions between risk-aware and risk-uncertain individuals indicate that ignoring differences in individuals’ capacity to assess risks could amount to persistent vulnerability and undermine climate-resilience efforts. While we use floods emblematically, these finding have consequences for the standard practice of dropping or bootstrapping uncertain responses, irrespective of the hazard, with implications for environmental management.@en

Understanding social and behavioural drivers and constraints of household adaptation is essential to effectively address increasing climate-induced risks. Factors shaping household adaptation are commonly treated as universal, despite an emerging understanding that adaptations are shaped by social, institutional and cultural contexts. Using original surveys in the United States, China, Indonesia and the Netherlands (N = 3,789), we explore variations in factors shaping households’ adaptations to flooding, the costliest hazard worldwide. We find that social influence, worry, climate change beliefs, self-efficacy and perceived costs exhibit universal effects on household adaptations, despite countries’ differences. Disparities occur in the effects of response efficacy, flood experience, beliefs in governmental actions, demographics and media, which we attribute to specific cultural or institutional characteristics. Climate adaptation policies can leverage the revealed similarities when extrapolating best practices across countries yet should exercise caution, as context-specific socio-behavioural drivers may discourage or even reverse household adaptation motivation.@en

Natural hazards, exacerbated by climate change, increasingly affect societies worldwide. The accelerating risks entail that private adaptation complement more traditional public climate change adaptation measures. Culture plays an important role in framing how individuals experience hazards and behave toward them. Yet, empirical research explicitly measuring whether and how climate change adaptation varies across cultures is lacking. To address this gap, we collect meta-analytic data on factors motivating individual flooding adaptation from 25 countries and more than 50 publications. Employing Hofstede's Cultural Rankings as a metric of national culture, we model the effect of culture on adaptation motivation of individual households using meta-regression analysis. We find a number of statistically significant relationships between culture and factors motivating private climate change adaptation. Hence, cultural context is vital to consider when designing and implementing climate change adaptation policies, simulating the uptake of individual hazard prevention measures, or integrating private adaptation in assessing costs of climate change in integrated assessment models. These findings are among the first to provide empirical evidence on the interaction effects between culture and private climate change adaptation motivation.@en