d*********t
发帖数: 4393 | 1 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% proba |
|
