When I moved to Des Moines, people made sure I knew about the flood of 1993. Interestingly, what people remembered about it was the lack of drinking water and that then-President Bill Clinton visited the area twice. Since nobody could tell me what made the water rise so much, I turned to resources available on the Internet for an answer. I found a scholarly article by Lee W. Larson, chief of the Hydrologic Research Laboratory at NOAA/National Weather Service. Larson’s article, presented at a conference in 1996, was called “The Great USA Flood of 1993.” The abstract notes that the 1993 flooding “was unusual in the magnitude of the crests, the number of record crests, the large area impacted, and the length of the time the flood was an issue.”
According to Larson’s article, the 1993 flood event covered nine states and lasted from May to September, including the July 11th flooding of Des Moines Water Works. That flood was no simple process of winter snow melting too rapidly for stream and river beds to hold the water pouring into them. A combination of hydrological events and thermal conditions over a span of more than a year was at fault, although this was explained in greater detail in another article that I thought I saved but have not been able to locate. So what are the underlying causes of the 2008 floods?
There are various resources for compiling a historical weather chart. A great place to start is with the monthly summaries prepared by the National Weather Service. The report released on June 1, 2008, noted that “May was the sixth consecutive month with temperatures cooler than normal.” This echos conditions in 1993 when evaporation was reduced due to cooler temperatures. In addition, recent months tended to be wetter than usual. April 2008 was the 9th wettest on record. Snowfall in January 2008 and in December 2007 was above normal. (A side note. The high on April 12, 2008, was 35 deg. F. This was the lowest high temperature recorded for that date since 1881, when the high was also only 35 degrees.) Now it is June and there is record-approaching rainfall but the soil is saturated and the rivers running high. According to information on the NWS’s Media Guide, as of 5:41 p.m. on June 10th, precipitation is at 8.41 inches. The normal for the entire month is 1.52 inches.
I remember being surprised last year to see the sidewalk that runs alongside the Des Moines River in the downtown area. It had been so long since the river was that low, I had forgotten about the sidewalk. Throughout the past winter, I kept commenting to myself how high the water was. There wasn’t any opportunity to make jokes about late summer mud flats. Maybe I should start a new adage, “When you can’t see the sidewalk, move to high ground.”
Note: A general floodplain map can be found at the county auditor’s website. Detailed maps are on FEMA’s website.
M.R. Field writes about local events for AroundDesMoines.com. 
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