What is a Flood Insurance Rate Map? What information is shown on this map?
The Flood Insurance Rate Map (FIRM), which is also referred to as the "flood map" or "NFIP map," is the insurance and floodplain management map prepared and issued by FEMA. Using detailed or approximate engineering analyses, the FIRM identifies Special Flood Hazard Areas and in areas studied by detailed engineering analyses, the FIRM shows Base Flood Elevations and regulatory floodways.

How does overland flow flooding happen?
The storm sewers and roadside ditches in Houston and Harris County are typically designed to handle a runoff rate of about one to two inches per hour. When the street drainage system capacity is exceeded, streets and roadside ditches store the excess runoff; but if enough additional rain falls, the excess runoff collects and flows overland, following the natural lay of the land. Eventually, yards and even residences may become flooded - even in areas significantly distant from a creek or bayou.

What is the 1% chance flood, the "100-year flood" or the Base Flood Elevation?
It is the flood elevation that has a 1% chance of being equaled or exceeded each year in a given location. Thus, the 100-year flood or 1% chance flood could occur more than once in a relatively short period of time. The Base Flood Elevation (BFE) is the elevation that the water will reach as a result of a 1% chance flood. The 1% chance flood is the standard used by the NFIP as the standard for floodplain management and to determine the need for flood insurance.

What is a Special Flood Hazard Area (SFHA)?
An area defined on a Flood Insurance Rate Map with an associated risk. A SFHA is defined as an area of land that would be inundated by the base, or 1% chance, flood. A structure located within an SFHA shown on an NFIP map has a 26-percent or greater chance of suffering flood damage during the term of a 30-year mortgage.

Why was the base flood chosen as the standard for NFIP purposes?
The base, 1% chance, flood standard was chosen after considering various alternatives. The standard constitutes a reasonable compromise between the need for building restrictions to minimize potential loss of life and property and the economic benefits to be derived from floodplain development. Development may take place within the SFHA, provided that development complies with local floodplain management ordinances, which must meet the minimum Federal requirements.

What are the different Special Flood Hazard Area designations in Harris County and what do they mean?
Zone A - Zone A is the flood insurance rate zone that corresponds to the 1% chance floodplains that are determined in the Flood Insurance Study (FIS) by approximate methods. Because detailed hydraulic analyses are not performed for such areas, no BFE are shown within this zone. Mandatory flood insurance purchase requirements apply.
Zone AH - Zone AH is the flood insurance rate zone that corresponds to shallow flooding areas that result from a 1% chance flood where average depths are between 1 and 3 feet. The BFEs derived from the detailed hydraulic analyses are shown at selected intervals within this zone. Mandatory flood insurance purchase requirements apply.
Zone AE - Zone AE is the flood insurance rate zone that corresponds to the 1% chance floodplains that are determined in the FIS by detailed hydraulic analyses. BFEs are shown within this zone at selected intervals. Mandatory flood insurance purchase requirements apply.
Zone V - Zone V is the flood insurance rate zone that corresponds to the 1% chance coastal floodplains that have additional hazards associated with storm waves. Because approximate hydraulic analyses are performed for such areas, no BFEs are shown within this zone. Mandatory flood insurance purchase requirements apply.
Zone VE - Zone VE is the flood insurance rate zone that corresponds to the 1% chance coastal floodplains that have additional hazards associated with storm waves. BFEs derived from the detailed hydraulic analyses are shown at selected intervals within this zone. Mandatory flood insurance purchase requirements apply.
Zone X Shaded - Zone X is the flood insurance rate zone that corresponds to areas of 0.2% chance flood, areas of the 1% chance flood with average depths of less than 1 foot or with drainage areas less than 1 square mile, and areas protected by levee from the 1% chance flood. No BFEs are shown within this zone.
Zone X - Areas determined to be outside 0.2% chance floodplain. No BFEs are shown within this zone.

Will my house be in the floodplains at the end of the project?
As a result of this project the regulatory floodplain boundaries will change. In some areas they may be larger and in others they may be smaller but this will not be known until maps are released for public review. This project will not change the natural floodplain but simply make property owners more aware of the risk that they have always been taking.

How can I find out if a structure is in a SFHA?
Your local floodplain administrator has copies of the Flood Insurance Rate Maps for your area and they can help you determine if a structure is in a SFHA. You can also do this online at the FEMA Map Store or by calling a FEMA map specialist at 1-877-FEMA MAP ((1-877-336-2627). When the new preliminary FEMA FIRMs are available you will be able to view them online, right here at www.tsarp.org.