What is a Flood Insurance Rate Map?

A flood insurance rate map is a government issued chart in the United States, created under the direction of the Federal Emergency Management Agency (FEMA) that seeks to show the risks of flooding in certain areas. The maps are designed around a 100 year flooding event, which means that there is a likelihood that a flood of a certain level, as depicted on the map, will happen once every 100 years. The flood insurance rate map is used by individuals, insurance companies, local officials, and lending institutions to determine what risks are associated with certain developed properties.

Two basic designs exist for flood insurance rate maps. The first is called a flat flood map, which is produced on a page that is 11 inches (approximately 28 centimeters) by 17 inches (43.18 cm). The other type of flood insurance rate map is called a z-fold map, which is a larger map that is folded much like a traditional road map. Each map includes an index and legend, which aids in reading the map.

In some cases, the flood insurance rate map for a community may be somewhat out of date. Some areas that are flood-prone may be more or less prone to flooding as situations change. A levy may be built, or the course of a river may change, leading to a different situation. Therefore, FEMA is in a nearly continuous process of updating flood insurance rate maps, with a priority given to the most flood-prone areas in the United States.

For most areas, a flood insurance rate map covers one specific region such as a county or city. For cities within a county, there is often a separate map product. In more recent rate map products, FEMA has produced maps that include information for all geographical areas the map covers. This makes it more convenient for those looking for information quickly. The maps are available from the FEMA website for free or those interested may also order hard copies.

The main use of a flood insurance rate map is to determine the risk of a flood tasking place. A potential buyer of property may look at the map to determine whether a property is in a desirable location. Insurers may charge higher rates for areas that are shown to be potentially at risk for more severe or frequent flooding events. Local emergency management officials can use the maps to plan where emergency services are most likely to be needed, and to help plan evacuations when emergency situations arise.