The terms "10
year", "50 year", "100 year" and "500
year" floods are used to describe the estimated probability of
a flood event happening in any given year. Their primary use is for
determining flood insurance rates in flood hazard areas. Using historic
weather and hydrograph data , experts derive
the estimated rate of flow or discharge
of a river or creek. A 10 year flood has a 10 percent probability of
occurring in any given year, a 50 year event a 2% probabaility, a 100
year event a 1% probability, and a 500 year event a .2% probability.
While unlikely, it is possible to have two 100 or even 500 year floods
within years or months of each other.
Living in or near
the foothills of the Rocky Mountains makes flash floods an extremely
serious concern. It is not a matter of "if" a major flood
will happen but rather when.
Following are links
for more information on flash floods in the region.
