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Development patterns and climate change are contributing to increasing flood risk across the United States. Limiting development in floodplains mitigates risk by reducing the assets and population exposed to flooding. Here, we develop two indexes measuring floodplain development for 18,548 communities across the continental United States. We combine land use, impervious surface, and housing data with regulatory flood maps to determine what proportion of new development has taken place in the floodplain. Nationwide from 2001 to 2019, 2.1 million acres of floodplain land were developed, and 844,000 residential properties were built in the floodplain. However, contrary to conventional perceptions of rampant floodplain development, just 26% of communities nationwide have developed in floodplains more than would be expected given the hazard they face. The indexes and the analyses they enable can help guide targeted interventions to improve flood risk management, to explore underlying drivers of flood exposure, and to inform how local‐to‐federal policy choices can be leveraged to limit hazardous development. 

Abstract Moving away from hazardous areas may be an important adaptive response under intensifying climate change, but to date such movement has been controversial and conducted with limited government or private-sector support. Research has emphasized resident perspectives on mobility, but understanding how professionals view it may open new avenues to shape future outcomes. Based on 76 interviews with professionals involved in climate responses in South Florida, we evaluate perceptions of adaptation goals, the potential role of climate mobilities in pathways supporting those goals, and associated constraints and enablers. The practitioners interviewed anticipate multiple types of climate mobilities will occur in the region, at increasing scales. Interviewees perceive climate mobilities at present, especially migration and gentrification where climate plays some role, as causing distributional inequities and financial and sociocultural disruptions, and they view existing adaptive strategies as best serving those who already have adequate resources, despite practitioners’ personal commitments to social justice goals. Although many practitioners feel prepared for their own, limited roles related to climate mobilities, they judge the region as a whole as being unprepared to support the retreat they see as inevitable, with a need for a more ambitious long-term transition plan. Achieving this need will be difficult, as practitioners indicate that climate mobilities remain hard to talk about politically. Nevertheless, interviewees believe some households are already considering moving in response to climate risks. Discussions of climate mobilities, through interviews and far beyond, may encourage more mindful choices about and engagement in climate-driven transformations. 

Managed retreat in the form of voluntary flood-buyout programs provides homeowners with an alternative to repairing and rebuilding residences that have sustained severe flood damage. Buyout programs are most economically efficient when groups of neighboring properties are acquired because they can then create unfragmented flood control areas and reduce the cost of providing local services. However, buyout programs in the United States often fail to acquire such efficient, unfragmented spaces, for various reasons, including long administrative timelines, the way in which buyout offers are made, desires for community cohesion, and attachments to place. Buyout programs have relied primarily on posted price mechanisms involving offers that are accepted or rejected by homeowners with little or no negotiation. In this paper, we describe four alternative strategies that have been used successfully in land-preservation agricultural– environmental contexts to increase acceptance rates and decrease fragmentation: agglomeration bonuses, reverse auctions, target constraints, and hybrid approaches.We discuss challenges that may arise during their implementation in the buyout context—transaction costs, equity and distributional impacts, unintended consequences, and social pressure—and recommend further research into the efficiency and equity of applying these strategies to residential buyout programs with the explicit goal of promoting spatial coordination.