Special Flood Hazard Areas (SFHA) Katy Neighborhoods

Aside from serving as a helpful warning to residents, another reason FEMA designates 100- and 500-year floodplains nationwide is to set flood insurance rates for properties.

Every community in the U.S. has a Flood Insurance Rate Map (FIRM), also referred to as a flood map. FEMA is responsible for identifying which communities are special flood hazard areas (SFHA). FEMA engineers and cartographers use data gathered from Flood Insurance Studies (FISs) to delineate and pinpoint SFHAs on flood maps.

In flood maps, neighborhoods built on a 100-year floodplain are considered SFHAs—areas that will be inundated by a 1-percent-annual-chance flood, also called the base flood or 100-year flood.

The 100-year flood is the regulatory standard used by most states and federal agencies in floodplain management programs, and is the basis used by the National Flood Insurance Program (NFIP) for setting insurance requirements nationwide.

Special Flood Hazard Areas are labelled as: Zone A, Zone AO, Zone AH, Zones A1-A30, Zone AE, Zone A99, Zone AR, Zone AR/AE, Zone AR/AO, Zone AR/A1-A30, Zone AR/A, Zone V, Zone VE, and Zones V1-V30.

Moderate Flood Hazard Areas are also shown on FIRMs and are labeled Zone B or Zone X (shaded). These are the areas between the limits of the 100-year flood (or base flood) and the 0.2-percent-annual-chance (or 500-year) flood. Neighborhoods built on 500-year floodplains fall under this category as well.

Minimal Flood Hazard Areas are labeled Zone C or Zone X (unshaded). These are lands outside the SFHAs that are also higher than the elevation of the 0.2-percent-annual-chance flood.

As an example, here are some neighborhoods in Katy and the hazard areas they fall under.