OC Flood Hazard Areas Polygons

The Federal Emergency Management Agency (FEMA) produces Flood Insurance Rate maps and identifies Special Flood Hazard Areas as part of the National Flood Insurance Program's floodplain management. Special Flood Hazard Areas have regulations that include the mandatory purchase of flood insurance for holders of federally regulated mortgages. In addition, this layer can help planners and firms avoid areas of flood risk and also avoid additional cost to carry insurance for certain planned activities. This layer is derived from the May 7, 2025 version Flood Insurance Rate Map feature class S_FLD_HAZ_AR. The vector data were then flagged with an index of 94 classes, representing a unique combination of values displayed by three renderers. (In three resolutions the three renderers make nine processing templates.) Repair Geometry was run on the set of features, then the features were rasterized using the 94 class index at a resolutions of 10, 30, and 90 meters, using the Polygon to Raster tool and the "MAXIMUM_COMBINED_AREA" option. Projection: Web Mercator Auxiliary Sphere Data Coordinate System: USA Contiguous Albers Equal Area Conic USGS version (contiguous US, Puerto Rico, US Virgin Islands), WGS 1984 Albers (Alaska), Hawaii Albers Equal Area Conic (Hawaii), Western Pacific Albers Equal Area Conic (Guam, Northern Mariana Islands, and American Samoa) Cell Sizes: 10 meters (default), 30 meters, and 90 meters Data Date: May 7, 2025; Version: 2026.1, Updated: March 2026联邦紧急事务管理局（Federal Emergency Management Agency, FEMA）作为国家洪水保险计划（National Flood Insurance Program）洪泛区管理的组成部分，会编制洪水保险费率地图（Flood Insurance Rate Map）并划定特殊洪水危险区域（Special Flood Hazard Areas）。特殊洪水危险区域设有相关监管规则，其中包括要求受联邦监管的抵押贷款持有人必须强制购买洪水保险。此外，该图层可帮助规划人员与相关企业规避洪水风险区域，同时避免为特定规划项目额外支付保险成本。 该图层基于2025年5月7日版本的洪水保险费率地图要素类S_FLD_HAZ_AR生成。后续对矢量数据标记了94类索引，该索引代表三种渲染器所展示的唯一值组合（在三种分辨率下，三种渲染器共生成9种处理模板）。 首先对要素集执行“几何修复（Repair Geometry）”工具，随后使用“多边形转栅格（Polygon to Raster）”工具，以“MAXIMUM_COMBINED_AREA”为选项，基于94类索引，分别以10米、30米和90米的分辨率完成栅格化处理。 投影方式为Web Mercator辅助球体（Web Mercator Auxiliary Sphere）；数据坐标系包括：美国本土阿尔伯斯等面积圆锥投影（USGS版本，覆盖美国本土、波多黎各、美属维尔京群岛）、WGS 1984阿尔伯斯投影（覆盖阿拉斯加）、夏威夷阿尔伯斯等面积圆锥投影（覆盖夏威夷）、西太平洋阿尔伯斯等面积圆锥投影（覆盖关岛、北马里亚纳群岛和美属萨摩亚）。 像元尺寸分别为10米（默认）、30米及90米。 数据日期为2025年5月7日；版本为2026.1；更新时间为2026年3月。