Levees

Levee data contains information about levees shown on the FIRMs that are accredited and known to be protecting against the 1% annual-chance flood, as well as levees that are provisionally accredited, and non-accredited. The purpose of this table is to document the accreditation status of levees, as well as associated information necessary to be shown on the FIRM. The spatial entities representing levees are lines, drawn at the centerline of levees, floodwalls and levee closure structures本堤防数据集收录了联邦洪水保险费率图（Flood Insurance Rate Map，简称FIRM）中展示的各类堤防信息：包括经认证且已知可抵御年发生概率1%洪水的堤防、临时认证堤防以及未认证堤防。本数据表旨在记录堤防的认证状态，以及需在FIRM上展示的全部必要配套信息。表征堤防的空间实体为线条，绘制于堤防、防洪墙及堤防封堵结构的中心线处。