As Flood Risks Increase across the U.S., It’s Time to Recognize the Limits of Levees

Major floods inundated Kansas City in 1903, 1908, 1943 and 1951, leaving thousands homeless and causing heavy economic damage. These disasters convinced civic leaders that more than piecemeal navigation and flood control projects along the lower Missouri were needed.

In 1944 they got their wish when Congress passed the Flood Control Act, which authorized construction of dozens of dams nationwide. One section of the bill, the Missouri Basin Plan, sought to convert the entire Missouri into what historian Donald Worster calls an “ornate hydraulic regime,” with five upstream dams for hydroelectric power, irrigation and recreation, as well as levees and a navigable barge channel from Sioux City to St. Louis.

Over the next decade engineers built levees and straightened and dredged the river channel. Upstream dams curbed the Missouri’s spring rise. In August 1955, Life Magazine reported that “U.S. engineers have finally clinched their victory over the rampaging Missouri River. Flood control … is already bringing prosperity to the valley it drains.”

The Limits of Levees
Today Kansas City and many other U.S. river towns are fortified behind levees and floodwalls, but faith in the idea of engineered flood control is starting to erode.

Disastrous Midwest flooding in the summer of 1993, which killed 50 people and caused $15 billion in damages, showed the limitations of this strategy. Floodwaters rose to unprecedented levels, eventually breaching or overtopping more than 1,000 levees.

After the waters ebbed, federal and state officials paid to move some homes and communities off floodplains to higher ground. However, this trend quickly reversed. By 2008, Missouri had authorized more than $2 billion of new development in zones that were flooded in 1993.

Many Kansas City residents still believe that higher, stronger levees will hold back future floods, and Congress has authorized millions of dollars to build them. But experienced engineers like retired Army Brigadier General Gerald Galloway, who coauthored a federal government assessment of the 1993 floods, warn that “there’s no such thing as absolute protection.”

For their part, many scientists and engineers have found that levees can exacerbate floods by pushing river waters to new heights. One 2018 study estimated that about 75% of increases in the magnitude of 100-year floods on the lower Mississippi River over the past 500 years could be attributed to river engineering.

What about commercial benefits from channeling rivers? Kansas City is still an economic hub, but railroads and highways have been more important than barges. The Missouri carries only a fraction of the tonnage shipped on other navigable rivers, such as the Mississippi, even though its channel has been expensively built and maintained for over 100 years.

Rethinking River Control
Levees also constrain cities’ relationships with rivers, walling off any connections for purposes other than commerce. Author William Least Heat-Moon captured this paradox when he traveled across the U.S. by boat in the late 1990s and observed that “Kansas City, born of the Missouri, has turned away from its great genetrix more than almost any other river city in America.”

More recently, however, Kansas City has begun to remember its interest and love for the Missouri. Riverside development and public spaces are fostering new physical and cultural interfaces with the river.

In my view, this year’s floods should lead to more of this kind of rethinking. River towns can start by restricting floodplain development so that people and property will not be in harm’s way. This will create space for rivers to spill over in flood season, reducing risks downstream. Proposals to raise and improve levees should be required to take climate change and related flooding risks into account.

Davenport, Iowa has embraced this approach. With a population of over 102,000, it is the largest U.S. river city without levees or a permanent floodwall. Instead Davenport has emphasized adapting to flooding by increasing public green spaces in the flood zone and elevating buildings that flank the Mississippi River.

Kansas City and other towns could advance this discussion by moving beyond strictly commercial visions of their waterways and considering this question: What does a healthy river of the future look like?

Amahia Mallea is Associate Professor of History, Drake University. This article is published courtesy of The Conversation.