Flood Elevation

Flood Elevation refers to the height of floodwaters at a specific location during a flood event, typically measured in feet above sea level. It represents the water level that is reached by floodwaters during a flood event, and it can apply to different types of floods (e.g., 100-year flood, 500-year flood, flash floods) and different stages of flooding.

Flood elevation is a critical factor in flood risk management and is used to determine:

  • Flood risk for a specific location
  • Required elevation for buildings and infrastructure to mitigate flood damage
  • Floodplain boundaries and the extent of areas that could be inundated by floodwaters

In some contexts, flood elevation can be used to refer to the Base Flood Elevation (BFE), which is the specific water elevation predicted to occur during a 100-year flood event. However, “flood elevation” can also refer more generally to any floodwater level, whether it’s during a large storm, a flash flood, or even a river flood event at a particular moment in time.

Example:

If a river’s flood elevation is 472 feet at a certain location, that means floodwaters are expected to reach that height during the flood event at that spot. This elevation may be referenced when planning development in flood-prone areas to ensure buildings are elevated above expected flood levels.

Flood Elevation and Base Flood Elevation (BFE) are related but not exactly the same. Here’s the difference:

Base Flood Elevation (BFE)

  • BFE refers specifically to the elevation of floodwaters during a 100-year flood event (the base flood). This is the level that floodwaters are expected to reach during a flood that has a 1% chance of occurring in any given year.
  • It is a designated elevation used by FEMA (Federal Emergency Management Agency) and other floodplain management agencies to define how high floodwaters may rise.
  • The BFE is used to determine floodplain management regulations, such as required building elevations (e.g., the lowest floor of a building must be above the BFE in flood-prone areas).
  • Typically expressed in feet above sea level (e.g., BFE = 472 feet).

Flood Elevation

  • Flood Elevation refers to the height of the water level during a flood event, but it can refer to different scenarios and flood events. It might describe current flood conditions (e.g., during a flood event) or anticipated flood levels for other types of floods (e.g., a 500-year flood or flash floods).
  • It is a general term that encompasses various water levels during floods, whereas BFE specifically refers to the 100-year flood level.

Key Difference:

  • BFE is a specific reference point used for regulatory purposes to guide construction, insurance, and planning.
  • Flood Elevation can refer to any elevation during any flood event, not necessarily the 100-year flood event.

In summary:

  • BFE is a specific standardized elevation used in flood zone mapping and construction codes.
  • Flood Elevation could refer to any water level during a flood, depending on the event or scenario.