Flood Hazard - Floodway

The Federal Emergency Management Agency (FEMA) has developed the Advisory Flood Zones. They provide full geospatial representation of the coastal and riverine Advisory Base Flood Elevations (1% annual chance coastal flood hazard), including both storm surge and wave components. FEMA is providing an advisory floodway to provide a geospatial limit of the channel of rivers or other watercourse and the adjacent land areas that must be reserved in order to discharge the base flood without cumulatively increasing the water surface elevation more than the designated height. FEMA has developed the Coastal A Zone to approximate the extent of breaking waves less than 3 ft and equal to and greater than 1.5 ft in height for the 1-Percent-Annual-Chance flood events美国联邦紧急事务管理局（Federal Emergency Management Agency, FEMA）已构建咨询性洪水区域数据集，该数据集完整刻画了沿海与河域的咨询性基准洪水水位（对应每年1%概率的沿海洪水灾害，包含风暴潮与波浪两种分量）的地理空间分布特征。同时，FEMA还发布了咨询性行洪通道数据，用于划定河道或其他水流域及其毗邻区域的地理空间边界：此类区域需被预留，以确保基准洪水下泄时，水面高程的累计增幅不会超出指定限值。此外，FEMA开发了海岸A区数据集，用于近似模拟百年一遇洪水事件中高度介于1.5英尺至3英尺之间的碎波波及范围。