Floodplain

Is my property in the Floodplain?
Before a person can receive a loan or other financial assistance from one of the affected agencies or lenders, an elevation certificate must be obtained to determine if the building is in a Special Floodplain Hazard Area (SFHA). The SFHA is the base (100-year) floodplain mapped on a Flood Insurance Rate Map (FIRM). On a FIRM areas contained within zones that begin with the letter "A" are considered within SFHA.
 
Copies of the FIRM are available for viewing at the Department of Public Works at City Hall, 300 Park Avenue, Suite 100W or by clicking here. Many lenders and insurance agents also have copies.
  
Development in the Floodplain

All work in the floodplain requires a permit, per Section 48-675 of City Code. Development in the floodplain is regulated by the City in order to protect the interests of the public. The departments of Public Works and Development Services work together to regulate uses, activities, and development, which will cause unacceptable increases in flood heights, velocities, and frequencies. All uses, activities, and developments that occur in flood prone districts must be protected against flood damage. During the city's permitting process, properties in or immediately adjacent to the 100-year floodplain are reviewed by City civil engineers for compliance with City code.

The City of Falls Church participates in the National Flood Insurance Program (NFIP) and the Department of Public Works (DPW) staff assists citizens with information regarding flood insurance, flood hazard maps, and elevation certificates.

Our Flood Hazard
Anywhere it rains, it can flood. The classical definition of a flood is a general and temporary condition where normally dry land is inundated by water. In the City of Falls Church, flooding is typically caused by major storms with heavy precipitation like hurricanes, inadequately sized or clogged drainage systems, intense periods of rainfall, and breakages of water mains.

It is important to know that although your property may not have experienced a flood in the past, this does not ensure you will not in the future. Flood risk is not based on history. Instead it is based on a number of factors, including:
  • Changes in land use stemming from development
  • Rainfall amounts and intensity
  • River-flow and tidal surge data
  • Soils
  • Topography
For more information on flood hazards, or to report a non-emergency flooding problem in the City of Falls Church, please contact the Department of Public Works at 703-248-5350.

Stormwater Modeling
The traditional approach to identify potential flood prone areas is by studying watersheds and then using computer modeling to determine stormwater runoff in our streams and storm drainage system. The Department of Public Works maintains a local stormwater model that analyzes several theoretical storm events. These events are based on statistical probability, and named after the frequency with which they are expected to occur (e.g. 2-,10-, 100-year storm events).

For example, a 2-year storm represents a rain event that statistically should occur 1 time every 2 years. The longer the frequency, the more intense the rain event becomes. In this case, the 100-year storm represents a massive rain event that should occur once a century. It is important to note, however unlikely it is, a 10-year storm can occur several times in a given year or on back to back days.