Whats the difference between a flood plain and a floodway?
The flood plain is the area inundated by the “base flood”, usually the 100-year flood. The floodway is the portion of the flood plain needed to actually convey the flood flow, while the remainder of the flood plain may be characterized by stagnant or low velocity flow. 9. Does a 100-year flood occur once every 100 years? No, the 100-year flood is defined as the flood that has a 1% chance of being equaled or exceeded in any given year. 100-year floods could occur at shorter intervals or even within the same year. 10. What is a “sunny day” dam failure? A “sunny day” dam failure is one that is not associated with a storm or flood wave. The Federal Energy Regulatory Commission (FERC) requires this failure mode to be evaluated for licensed dams, as well as failure during the design storm (which depends on the dam size and hazard classification). The impoundment is assumed to be at its normal elevation, and the failure mode is usually assumed to be a piping failure for earthen embankments, o
