FIRM Floodways

This dataset reflects the most recent Physical Map Revision (PMR) , and removal of polygons within incorporated areas. The FIRM is the basis for floodplain management, mitigation, and insurance activities for the National Flood Insurance Program (NFIP). Insurance applications include enforcement of the mandatory purchase requirement of the Flood Disaster Protection Act, which "... requires the purchase of flood insurance by property owners who are being assisted by Federal programs or by Federally supervised, regulated or insured agencies or institutions in the acquisition or improvement of land facilities located or to be located in identified areas having special flood hazards," Section 2 (b) (4) of the Flood Disaster Protection Act of 1973. In addition to the identification of Special Flood Hazard Areas (SFHAs), the risk zones shown on the FIRMs are the basis for the establishment of premium rates for flood coverage offered through the NFIP. The DFIRM Database presents the flood risk information depicted on the FIRM in a digital format suitable for use in electronic mapping applications. The DFIRM database is a subset of the Digital FIS database that serves to archive the information collected during the FIS. The Digital Flood Insurance Rate Map (DFIRM) Database depicts flood risk information and supporting data used to develop the risk data. The primary risk classifications used are the 1-percent-annual-chance flood event, the 0.2-percent-annual-chance flood event, and areas of minimal flood risk. The DFIRM Database is derived from Flood Insurance Studies (FISs), previously published Flood Insurance Rate Maps (FIRMs), flood hazard analyses performed in support of the FISs and FIRMs, and new mapping data, where available. The FISs and FIRMs are published by the Federal Emergency Management Agency (FEMA). The file is georeferenced to earth's surface using the State Plane projection and coordinate system. The specifications for the horizontal control of DFIRM data files are consistent with those required for mapping at a scale of 1:12,000. ** The following work was subsequently performed on May 13, 2008 by Lee County. The flood polygons were intersected with the BFE lines to create discrete polygons and assigned the BFE in a new field. The ”Floodway” field was populated with the identified flooding source or "Outside" for areas not within the floodway. ** Properties that have been issued Letters of Map Change (LOMC), as well as Physical Map Revisions (PMR) are added to this feature class periodically.** *** This dataset reflects unincorporated Lee County ***本数据集反映了最新的物理地图修订版（Physical Map Revision, PMR）以及建制区域内多边形的剔除操作。洪水保险费率图（Flood Insurance Rate Map, FIRM）是美国国家洪水保险计划（National Flood Insurance Program, NFIP）开展洪泛区管理、减灾及保险相关工作的核心依据。保险相关工作包括落实《洪水灾害保护法案》中的强制投保要求，该法案第2(b)(4)条规定："对于接受联邦项目援助，或由联邦监管、规制或保险的机构协助购置或改良位于已识别的特殊洪水危险区内或拟位于该区域内的土地设施的物业所有者，要求其购买洪水保险"。除识别特殊洪水危险区（Special Flood Hazard Areas, SFHAs）外，洪水保险费率图上标注的风险分区也是制定通过国家洪水保险计划提供的洪水保险保费费率的基础。数字洪水保险费率图数据库（Digital Flood Insurance Rate Map Database, DFIRM Database）以数字化格式呈现洪水保险费率图上的洪水风险信息，适配电子制图应用的使用需求。该数据库是数字洪水研究数据库（Digital FIS database）的子集，用于归档洪水保险研究（Flood Insurance Studies, FIS）过程中收集的相关信息。数字洪水保险费率图数据库呈现了用于生成风险数据的洪水风险信息及配套支撑数据。所采用的主要风险分类包括：年超越概率1%的洪水事件、年超越概率0.2%的洪水事件，以及最低洪水风险区域。本数据库源自洪水保险研究（Flood Insurance Studies, FISs）、此前发布的洪水保险费率图（FIRMs）、为支撑洪水保险研究及洪水保险费率图所开展的洪水灾害分析，以及可获取的最新制图数据。洪水保险研究与洪水保险费率图均由联邦紧急事务管理局（Federal Emergency Management Agency, FEMA）发布。本数据集采用州平面投影与坐标系实现与地球表面的地理配准。DFIRM数据文件的水平控制规范与1:12000比例尺制图的要求保持一致。**以下工作由李县于2008年5月13日完成：将洪水多边形与洪水基准高程（Base Flood Elevation, BFE）线相交以生成离散多边形，并在新增字段中赋值对应洪水基准高程。"洪水通道"字段将填充已识别的洪水来源信息，若区域不在洪水通道范围内则标注为"Outside"。**已发放地图变更函（Letters of Map Change, LOMC）的物业以及物理地图修订版数据会定期添加至该要素类中。***本数据集仅涵盖李县非建制区域***