Map Information; This is a map of the continental United States, Puerto Rico, Alaska, and Hawaii including state boundaries. It is entitled “Frequency of Flood Events by County: 1996-2013”. It includes data from the NCDC Storm Events database, and includes all events in the database categorized as Costal Flooding, Flooding, Flash Flooding, Lakeshore Flooding, and Storm Surge.
Map Description: The map displays the frequency of recorded floods from 1996-2013 represented by a four point scale. The first and highest frequency group in the scale represents counties with between 101 and 4,114 flood events. The counties with this frequency level cover half of Hawaii and parts of California, Arizona, New Mexico, Texas, Missouri, Indiana, Pennsylvania, New Jersey, and Florida. The second highest frequency group in the scale represents counties with between 21 and 100 flood events. This second frequency level covers the other half of Hawaii and most or part of every state and Puerto Rico, with the exception of Wyoming. The third level of frequency represents counties with between 1 and 20 flood events. This third and lowest frequency level covers part of every state except Hawaii, and parts of Puerto Rico. The fourth and final group in the scale represents counties with no recorded flood events. The areas for this level cover most of Puerto Rico, part of Alaska, and only a few counties in Washington state, Oregon, California, Idaho, Nevada, Utah, Montana, Wyoming, Colorado, New Mexico, North Dakota, Nebraska, Texas, Minnesota, Michigan, Georgia, and South Carolina. In all, approximately 95% of the US is under one of the first three frequency groups with some recorded flooding.
Federal Emergency Management Agency
ORR Mapping and Analysis Center, Washington, D.C., March 13, 2014. Sources: ESRI, USGS.