What are floods?

Floods are among the most frequent and costly natural disasters. They range from a few inches of water to several feet deep and can come in quickly or build gradually. In Texas, conditions that cause floods include heavy rains that saturate the ground and storm surges. Flash flooding occurs suddenly due to rapidly rising water along a stream or low-lying area, leaving little time for affected residents to evacuate their home or business, or their car if attempting to drive across a flooded roadway. Because flash floods can be sudden, roadways can be covered in swiftly moving floodwater, making them unsafe and impassable. Did you know that in certain flooding conditions, a vehicle can be washed away in less than 12 inches of fast-moving floodwater? Most flood-related deaths are due to motorists attempting to cross a flooded low-water crossing or road. Know your flood risk, and ‘Turn Around, Don’t Drown®”!

FLOOD HAZARD AREAS

What exactly is a 100-year flood?

The phrase “100-year flood” has caused much confusion over the years. Many believe that it is a flood that occurs every 100 years. However, the phrase really means a flood that has a 1% chance of occurring in any given year. Statistically speaking, over a 30-year period, a 100-year flood has a 26% chance of occurring. A 500-year flood has a 0.2% chance of happening in any given year and a 6% chance in any 30-year period. The risk of flooding also increases as you move closer to the stream centerline and deeper into a 100+year floodplain, as shown below. This is because the susceptibility to flooding from more frequent events such as the 25-year flood increases as you get closer to the flooding source.

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Zone A

• Fill is allowed.
• Garage can be located below BFE if properly vented

Zone V

• Fill is prohibited
• Structures must be elevated using piers, pilings or columns
• Areas below BFE must be used solely for parking, access or storage and must be constructed with breakaway walls
• A V Zone Design Certificate must be submitted prior to permit issuance. The certificate must be certified by a registered professional engineer or architect that the design and planned methods of construction meet NFIP requirements.

• A non-conversion agreement* must be submitted after building final and before Certificate of Occupancy is issued for new construction, including additions, permits with or without a proposed enclosure.

  *A non-conversion agreement for new construction, including additions, with or without an enclosure below base flood elevation is an agreement that the enclosed space will not be converted to a habitable living space. The area must remain solely used for parking, access or storage.

Zone A

• • Fill is allowed.
  • Garage can be located below BFE if properly vented.

Zone V

• • Fill is prohibited.
  • Structures must be elevated using piers, pilings or columns.
  • Areas below BFE must be used solely for parking, access or storage and must be constructed with breakaway walls.
  • A V Zone Design Certificate must be submitted prior to permit issuance. The certificate must be certified by a registered professional engineer or architect that the design and planned methods of construction meet NFIP requirements.
  • A non-conversion agreement* must be submitted after building final and before Certificate of Occupancy is issued for new construction, including additions, permits with or without a proposed enclosure.

*A non-conversion agreement for new construction, including additions, with or without an enclosure below base flood elevation is an agreement that the enclosed space will not be converted to a habitable living space. The area must remain solely used for parking, access or storage.