When the levee broke in Davenport, there was little warning. People were trapped in their homes and businesses and cars were left stranded in the road.
Thankfully, no one was killed or injured. But that might not be the case when the next levee breaks. Which is why I’m always slightly distracted these days, ears perked, straining to hear the air horns should another levee break.
Traveling around the Quad Cities is an exercise in patience. Multiple bridge approaches are flooded and train traffic that has been re-routed because of the flood blocks other major thoroughfares at a near steady pace. Even the Centennial Bridge, built to withstand a 100-year flood event, is buttressed by HESCO barriers and pumps as Davenport strains to keep it open.
The 100-year flood event is the critical marker for infrastructure and the Centennial Bridge in Davenport was built to span such an event. To see its approach flooded out is to witness something greater — a flood more severe than the almighty 100-year event.
Sadly, we aren’t the only ones with bridge problems. This past weekend the Champ Clark Bridge in Louisiana, MO was closed due to flooding. Located at Louisiana, MO, it is the only bridge that crosses the Mississippi for over one hundred miles and is a major transportation route connecting I-70 to I-72. Unfortunately the Champ Clark Bridge was not built to these “new” 100-year flood frequency standards and was totally swamped with the rising river.
During the Great Flood of 1993, bridge closures were cited as a major economic burden to the region, causing countless delays for people and goods, driving up prices, and closing local business. Experiencing these bridge and road closures begs two questions in my mind – Is the 100-year event still relevant? And, how can we bring our infrastructure up to date to deal with climate change?
Every year, someone on the Upper Mississippi River experiences a statically unlikely 100-year flood event and St. Louis seems to have at least a few 100-year events annually. Is the science and math behind the predictions of these events wrong, or simply out of sync with the current climate conditions? Or is something else going on? Likely all three.
With climate change, the Midwest is experiencing more frequent severe precipitation events, which means more snow in the winter and rain in the spring, which is a deadly recipe for Mississippi River flooding. Unfortunately, the flood frequency statistics are based on past rainfall data, which may no longer be relevant in our new and quickly changing climate. Additionally, the Mississippi basin is over engineered as communities pursue higher levees and more water moves off the landscape faster via an elaborate network of drain tile and channelized streams.
This is why the Upper Mississippi River between Muscatine, IA and Hamburg, IL was listed among America’s Most Endangered Rivers. Along this 200- mile stretch of the Mississippi, several levee districts have over-built their levees and models show that their actions may be causing some parts of the Upper Mississippi to see almost 2 more feet of water.
So how can we plan better and improve our infrastructure to limit the transportation and associated economic disruptions? To start, we need to update the so-called “100-year” and “500-year” event profiles and flood maps with data based on more recent and projected precipitation trends. Bridge approaches need to be well outside of the updated 100-year events and other critical infrastructure needs to be moved out of the floodplain.
By moving such critical infrastructure out of the floodplain, it will allow the flood waters to slow down over the land, protecting vulnerable people and property.
We also need to get a handle on flood fighting. Today’s standard flood fight is every man for himself. But sandbagging creates another layer of unpredictability in an already chaotic natural disaster and levees are compromised by pushing sand up to the top from the base of the levee, making them taller, but weaker.
Instead of the current flood control approach to river management, state and federal agencies need to lead our region to a more reliable flood risk management strategy that uses more modern, nature-based flood risk management approaches, such as floodplain reconnection and restoration. Such a plan would assure residents that the flood water will go “here” and not “there,” because giving the river room to flood is the best way to protect people and property.