Understanding Flood Hazards
There are several flood principles that should be considered to determine your facility’s exposure to flood waters and the type of protection to be deployed:
- Duration: It is important to know if flood waters are expected to recede quickly or may be trapped due to the slope of the land. The longer a facility is exposed to flood waters, the greater potential for flood-proofing failures due to a breach in the protection.
- Depth: Flood waters greater than 3 feet create hydrostatic pressure on walls that can cause cracks in masonry and greatly increase the potential of collapse to unreinforced masonry. When estimating the potential depth of flood waters, it is always best to include a safety factor to account for inaccuracies in the estimate.
- Velocity: As flood water velocity increases, so does the pressure exerted on flood protection. River flooding can be very fast moving water at first and then may settle down. Coastal locations may be exposed to wave action from storm surge.
- Water Condition: Many times flood waters are dirty, brackish or contaminated with biological and chemical materials including waste water, sewage, pesticides, industrial waste, toxic and non-toxic chemicals, or oils. Debris that is churning in the water can impact buildings and flood protection systems, create breaches in the protection and cause extensive damage.