With increasing costs of floods across the globe, interest has grown in using managed retreat strategies, such as home buyouts, for flood mitigation. For years, national-level estimates of the benefits of flood mitigation investments in the United States have been estimated as being on the order of 4:1 (USD) or more recently 6:1 (USD), according to the Federal Emergency management Agency and others. Localized evaluation of the true costs and benefits for communities is limited, however, and primarily centered around avoiding direct structural damages. Home buyouts, where individuals’ properties are purchased and removed from risk while reducing impervious areas, are only one of many mitigation options captured in the national estimates. This paper presents a scenario analysis to estimate a localized return on investment of a home buyout program for Nashville-Davidson County, Tennessee in the United States that justifies investment in such programs. It considers the cost of buyouts across the community over several decades. It also compares those costs to benefits such as changes in stormwater attenuation, damages avoided, and exposed populations for a specific extreme flood event. Overall, at a localized scale, the study demonstrates that the return on investment is comparable to national averages, and that proactive implementation significantly increases the value of benefits relative to costs. The approach has potential applicability to other areas in the United States and beyond. It can be used to make the case for investment in such mitigation programs utilizing similarly available data.

随着全球洪水成本的增加，人们越来越有兴趣使用有管理的撤退策略（例如购房）来缓解洪水。多年来，根据美国联邦紧急事务管理局的数据，国家一级对美国防洪投资的收益估计约为4：1（USD）或更近期的6：1（USD）和别的。但是，对社区的真实成本和收益的本地化评估是有限的，并且主要集中在避免直​​接的结构性破坏上。购房者购买个人财产并减少风险，同时减少不透水区域，这只是国家估算中许多缓解措施之一。本文提出了一种情景分析，以估算美国田纳西州纳什维尔-戴维森县购房计划的本地化投资回报率，这可以证明对此类计划进行投资的合理性。它考虑了几十年来整个社区的收购成本。它还将这些成本与收益进行了比较，例如雨水衰减的变化，避免的损失以及特定极端洪水事件造成的人口裸露。总体而言，该研究表明，在局部规模上，投资回报率可与全国平均水平相媲美，并且积极实施将大大提高收益相对于成本的价值。该方法在美国及其他地区具有潜在的适用性。