Calculating the odds of flooding in Winneshiek County

Staff members of the Iowa Flood Center at the University of Iowa will be in Decorah Wednesday night to present their results of flood modeling involving the Upper Iowa River in the Decorah area.

Appearing on the "Iowa Press" program on Iowa Public Television recently, Iowa Flood Center Director Witold Krajewski told reporters the heat and humidity in Iowa has been increasing in recent years, which has increased the likelihood of precipitation.

That, of course, affects the probability of flooding in Iowa.  Most flood modeling is based on "100-year floods."  Krajewski says "Many communities have building permits based on the notion of a 100-year flood, which is a flood that has a one percent chance annually of happening.  But if you weigh it over 30 years, which is the typical period for a house mortgage, then the probability that at some point you will be flooded by an event like that is 26 percent."

In the same program, Iowa Public Television search for how many times Iowa counties have had disaster declarations because of flooding.  That graphic showed that Winneshiek County has had among the most disaster declarations in the state--from 13 to 17.

The full interview with Krajewski can be seen at: http://www.iptv.org/iowapress/story/30984/witold-krajewski-and-tyler-olson-discuss-recent-flooding