As I write this late on Thursday, June 12, 2008, the crest of the Des Moines River is expected to arrive in downtown Des Moines very early Saturday morning and stay just below the levee’s height. About two miles upriver in the Birdland Marina 
area, the crest is expected to be four inches above the levee. Tonight volunteers from across the metro are helping to fill sand bags in Union Park to place on top of the levee around the threatened neighborhood. Earlier in the day, Iowa National Guard troops were also moving sand bags in the area.
In Cedar Rapids, about 120 miles to the east of Des Moines, a curfew is in place as the Cedar River has inundated numerous blocks. Officials in both Cedar Rapids and in Des Moines have talked about the 500 year flood plains. Many residents of eastern Iowa have been quoted on newscasts stating they are seeing water in places where it never reached in 1993.
Despite similarities in weather patterns, no two years are going to be exactly alike. That is true when there is an El Nino effect and it is true with rainfall. In addition, even though people have been quoted with choice comments about 100-year floods happening only fifteen years apart, think of all the additional construction that has changed runoff routes and on-site drainage capabilities in that little span of time. A 500-year flood is even more problematic. It was not quite 500 years ago when Hernando De Soto saw the Mississippi River and half a century later before Father Marquette and others explored the river from the north. Iowa was only beginning to be settled 200 years ago. In that time the Raccoon River has been rechanneled and numerous dams have been placed along the Des Moines River. With so many changes made over the years, can we even clearly define a 100-year flood, let alone a 500-year flood?
Sure, we can use satellite imagery and GPS software to map elevations and use computers to calculate various flows of water under numerous weather conditions. We can also look at the layers of sediment and give an educated guess as to where flood waters reached 500 years ago. We can determine the amount of water soil in any given area can hold. These are tools that can help decision-makers determine whether the cost-benefit ratio of a particular project is justifiable. Yet, they are extremely unreliable tools in telling a homeowner, tenant, or visitor if their present accommodations are going to be washed away in any given flood event.
With all the news coverage of the big rivers, I have not heard anything about Fourmile Creek in the past couple of days. Pressure from Des Moines River flooding on the ground water table caused water to seep through cracks into the basement of City Hall. The Animal Rescue League has set up facilities to board animals that are evacuated along with their human companions.
The downtown Farmers’ Market was cancelled. That will hurt many of the vendors financially. It had to be done as a matter of public safety, though. Capital City Pride decided to reschedule their events for later in the year. The Hy-Vee Triathlon also is taking a hit as it had to relocate. Officials won’t know until next week if the competition will still be an Olympic qualifying event. Activities planned for the northwestern part of the city, away from creeks and rivers are still being held. These include the NCAA track and field events at Drake University and something in Beaverdale.
M.R. Field covers local events for AroundDesMoines.com.
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