A stream flooding its banks
Flood frequency refers to how often a flood of a given size can be expected for a certain location. It can be represented as the probablility that a particular size of flood will occur each year. Flood frequency analysis is a useful tool for engineers when planning bridges or other projects near bodies of water. Does this Spark an idea?
Instructions
1. Find annual peak flow data for the river or stream you are interested in. Data for the U.S. can be found on the USGS Web site. The more years of data on record, the more accurate your analysis will be.
2. Calculate the recurrence interval for the size of flood you are analyzing. The recurrence interval simply equals the number of years on record divided by the number of flood events.
3. Use the recurrence interval to calculate the probability that a flood event will happen in any year. This probabilty equals one divided by the recurrence interval. For example, a flood with a 100-year recurrence interval has a 1 percent chance of happening this year or any year in the future.
Tags: recurrence interval, Flood frequency, size flood
