Rainfall Frequency of the Midwest by Huff and Angel--A Miracle, An Act of God, A 100 Yr. Event?

(click on the post for the "Gold standard" of rainfall frequency of the Midwest. This post refers to page 49. )


Extreme 100 year events occur by definition----- very rarely----Hence in the 80 years period which this study covers, the data for 100 year events is heavily skewed to an event in southern Illinois in 1910 and also one in Indiana in March of 1913.

Because there is limited data, there is an increased possiblity of error of inference from the data. One cannot simply read across the chart and come up with a conclusion that is reasonable----that is the bottom line of the caution in this report---on page 49.

The rainfall and the runnoff are two very different things. The report that is the gold standard does not consider the effect of runnoff that is improperly handled. It only covers rain from the sky.

An expert that was using data from the studies thus---would add extra layers of protection to prepare for the possiblity of error. In answer to the question, "Have you considered the possiblity that you may be wrong?, the expert would discuss the additonal plans for controlling runnoff in the event that the data from the past was of so limited amount that it was not correct, or the possiblity that weather patterns could be getting worse---which along an axis near us is the case. Also the expert would consider the runnoff properties of the soil in the area.

Click on the post for the full document. It is great reading right before bed.