Comparison of the 2011 flood event

You might ask, “So how did this year’s event compare to other flood events?” Well, I dug up some information to try and put things in perspective. The average rainfall in April and May is 9.5 inches. This, of course, varies from year to year. Surprisingly, last spring was average (we received 9.36 inches), but after that the bottom dropped out and we spent the rest of the year in a serious drought…which by the way, I think it is safe to say we are out of the woods.

Past Precipitation Totals During Wet Springs

I dug a little deeper to compare this spring with other wet years according to the Poplar Bluff weather station database. What I found was pretty interesting.

• In 1957, between April-May the total precipitation = 21.28 inches

• In 1973, between March-April the total precipitation = 20.95 inches

• In 1976, between April-May the total precipitation = 14.4 inches

• In 2008, between March-April the total precipitation = 17.63 inches

• In 2011, between April-May the total precipitation = 24 inches

In the past, our wet springs have totaled between 15-20 inches over two months. The 2008 flood was bad because we experience 12 inches within a couple days. This year was somewhat similar to 2008 because it was too much water in a very short amount of time. Instead of 20 inches of rain spread out over 60 days, it was 22.4 inches within 10 days. This is twice as much rain in 16 percent of the normal period of time.

Drainage and Floods

The Bootheel has one of the most intricate drainage systems in the United States with more than 6,000 miles of ditches. So why didn’t it work? Or did it work?

Let’s try to think about this flood and the ditches like our road system. Typically, you can drive from point “A” to “B” without many problems. You may have to slow down on some corners and at a few stoplights, but overall your “flow” of travel isn’t inhibited. In a similar way, our ditches work well during small rain events. A few corners and a little downed debris (those pesky beavers) don’t compromise the daily function of the ditches and water moves on downstream.

However, during peak rush hour when everyone is on the road it is a different story. You might experience this as you travel this Memorial Day weekend. The sheer number of cars exceeds the capacity of the traffic system. Delays are inevitable as cars back up because there is no alternative route and not enough space. In a similar fashion, the 2011 flood event was caused by too much rain all at once. A giant “water jam” occurred through the Bootheel’s ditch system. There was too much water for the infrastructure and it spilled out onto the adjacent land.

Like traffic jams, these periods of congestion don’t last forever. Over the last few weeks, water levels have definitely dropped as water has continued to flow downstream. This year’s rain event has definitely raised the bar in terms of the magnitude and scale of flooding that we’ve seen in recent years. Hopefully, we won’t see rainfall like this anytime soon.

If you do find yourself in a bit of a traffic jam, don't be too worried if your thoughts drift and you start thinking about water, wetlands and the surrounding landscape.  It happens to me all of the time -- even when I'm not in traffic. 

Travel safe and have a good weekend.