I learned something new today, adding to my rapidly increasing repertoire of knowledge I didn't want to know about flooding as this disaster progresses.
The experts are now calling this a 500-year flood event (compared to a 100-year flood event in '93). I thought it meant this was a kind of flood that happens only once every 500 years. Not so.
According to the weather guy on our local news, a 100-year flood is calculated to be the level of flood water expected to be equaled or exceeded every 100 years on average. But the 100-year flood is more accurately referred to as the 1 percent flood, since it is a flood that has a 1 percent chance of being equaled or exceeded in any single year.
Wikipedia notes that a 100-year flood has approximately a 63.4 percent chance of occurring in any 100-year period, not a 100 percent chance of occurring; 500-year floods have a 0.2% chance of occurring in any given year.
This afternoon's headline on the Press-Citizen Web site read
simply --
WANTED: Ark
The latest word is that the Iowa River is not even expected to crest until a week from Friday. And that's assuming we don't get any more rain.
At last check with the National Weather Service, we're talking anywhere between 2 and 5 inches of rain forecast in the next two days.
The experts are now calling this a 500-year flood event (compared to a 100-year flood event in '93). I thought it meant this was a kind of flood that happens only once every 500 years. Not so.
According to the weather guy on our local news, a 100-year flood is calculated to be the level of flood water expected to be equaled or exceeded every 100 years on average. But the 100-year flood is more accurately referred to as the 1 percent flood, since it is a flood that has a 1 percent chance of being equaled or exceeded in any single year.
Wikipedia notes that a 100-year flood has approximately a 63.4 percent chance of occurring in any 100-year period, not a 100 percent chance of occurring; 500-year floods have a 0.2% chance of occurring in any given year.
This afternoon's headline on the Press-Citizen Web site read
simply --
WANTED: Ark
The latest word is that the Iowa River is not even expected to crest until a week from Friday. And that's assuming we don't get any more rain.
At last check with the National Weather Service, we're talking anywhere between 2 and 5 inches of rain forecast in the next two days.
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