FEMA Flood Hazard Areas SCTDD

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. Dataset Summary Phenomenon Mapped: Flood Hazard Areas Coordinate System: NAD 1983 Tennessee State Plane Extent: SCTDD region Source: Federal Emergency Management Agency Publication Date: March 3, 2026 This layer is derived from the March 3, 2026 version of the National Flood Hazard Layer feature class S_Fld_Haz_Ar. The data were aggregated into eight classes to produce the Esri Symbology field based on symbology advice provided by FEMA. All other layer attributes are derived from the National Flood Hazard Layer feature class S_Fld_Haz_Ar. The layer was projected to Web Mercator Auxiliary Sphere, then the repair geometry geoprocessing tool was run on it, using the OGC option. Its resolution was set to 0.0001 meters. To improve performance Flood Zone values "Area Not Included", "Open Water", "D", "NP", and No Data were removed from the layer. Areas with Flood Zone value "X" subtype "Area of Minimal Flood Hazard" were also removed. An imagery layer created from this dataset provides access to the full set of categories in the National Flood Hazard Layer, including reasons why something is not in a flood zone.

美国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，负责编制洪水保险费率地图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要求，其中包含强制购买洪水保险的条款。
数据集摘要
制图覆盖现象：洪水危险区域
坐标系：NAD 1983田纳西州平面坐标系（NAD 1983 Tennessee State Plane）
覆盖范围：SCTDD区域
数据来源：美国联邦紧急事务管理局
发布日期：2026年3月3日

该图层源自2026年3月3日版本的国家洪水危险图层要素类S_Fld_Haz_Ar。依据FEMA提供的符号化建议，数据被聚合为8个分类，以生成Esri符号化字段。其余图层属性均源自国家洪水危险图层要素类S_Fld_Haz_Ar。

该图层先被投影至Web墨卡托辅助球体坐标系（Web Mercator Auxiliary Sphere），随后使用OGC选项运行几何修复地理处理工具，其分辨率设置为0.0001米。为提升图层运行性能，已从图层中移除洪水分区值为"Area Not Included"、"Open Water"、"D"、"NP"及无数据（No Data）的区域。同时亦移除了洪水分区值为"X"且子类型为"最小洪水危险区域"的区域。

基于该数据集创建的影像图层可访问国家洪水危险图层的全部分类信息，包括某区域未被划入洪水危险区域的具体原因。