In the United States, the Federal Emergency Management Agency (FEMA) delineates 100-year flood zones to define risks, regulate flood insurance premiums, and inform flood management. Evidence indicates that FEMA flood maps are incomplete, calling much of our current knowledge of U.S. flood hazard inequities into question. We use a state-of-the-art flood hazard model and census tract-level dasymetrically mapped sociodemographic data to examine flood risk inequities in the Greater Houston area, where increasingly frequent and damaging flood events are occurring. We innovate by analyzing federally overlooked 100-year flood risks (100-year flood zones delineated by the flood hazard model that are outside of FEMA 100-year flood zones). Results indicate that nearly 1 million Greater Houston residents live in federally overlooked 100-year flood zones. Black and Asian neighborhoods experience disproportionate risk in federally overlooked pluvial and fluvial flood zones, and Hispanic neighborhoods experience disproportionate risk in all federally overlooked zones (coastal, pluvial, and fluvial). High flood risk and the relative lack of protective resources in federally overlooked 100-year flood zones doubly jeopardizes racial and ethnic minority communities. Our findings and recent flood disasters suggest that future flood impacts in Greater Houston will be catastrophic and unjust unless FEMA revises their risk mapping and management approach to promote long-term public safety and social equity.

在美国，联邦紧急事务管理局 (FEMA) 划定 100 年一遇的洪水区，以界定风险、规范洪水保险费并为洪水管理提供信息。有证据表明 FEMA 洪水地图不完整，使我们目前对美国洪水灾害不公平性的大部分认识受到质疑。我们使用最先进的洪水灾害模型和人口普查区级别的三维测绘社会人口统计数据来检查大休斯顿地区的洪水风险不平等，该地区正在发生越来越频繁和破坏性的洪水事件。我们通过分析被联邦政府忽视的问题来进行创新100 年一遇洪水风险（洪水灾害模型划定的 100 年一遇洪水区位于 FEMA 100 年一遇洪水区之外）。结果表明，近 100 万大休斯顿居民生活在联邦政府忽视的 100 年一遇洪水区。黑人和亚裔社区在联邦忽视的洪水和河流洪水区经历了不成比例的风险，而西班牙裔社区在所有被联邦忽视的地区（沿海、洪水和河流）经历了不成比例的风险。在联邦忽视的 100 年洪水区，高洪水风险和相对缺乏保护资源对种族和少数民族社区造成双重危害。