The U.S. has long built levees to protect communities from floods, but levees have a side effect: by lowering flood risk in one area, they raise the flood risks for neighboring towns. Few scientists study this problem, even as deadly record floods inundate the Midwest. And regional coverage of levee disputes can often be reduced to he-said/she-said arguments. So we set out to investigate the decision-making behind building levees, showcasing the flaws in planning and the human harm, with a foundation in science. We knew we needed to illustrate the counterintuitive concept that levees could make flooding worse, and we knew we needed to innovate to capture the interest of readers.
So we built a tiny community and a miniature levee, and we flooded it.
Hiring scientists at the University of Minnesota who research fluid dynamics, we built a 10-foot by 13-foot model. It was scientific, visually attractive and simple enough for the average viewer to grasp, and it came complete with tiny wooden houses, carved by the fathers of two of our journalists and painted by hand as a newsroom-wide project. In partnership with Vox, our video journalists wore hip waders during the four-day, six-camera filming session. The lab’s laser scanner captured millimeter-resolution data of the topography of the basin and water heights. The results are a visual interactive that allows the audience to test different levee scenarios and see how the flooding changes as the water flows faster and levee walls grow taller.
We created an array of interactive graphics to explain the effects of levees in the real world; much of the data behind these graphics were obtained by or created by us exclusively. We also told parts of the story in audio form, through a podcast with Reveal.
Our project provided local officials and residents information that was otherwise out of reach. Communities had been awaiting a model from the Army Corps that showed how overbuilt levees in Illinois raised flood levels upstream and across the river. The model was a public record, but its format was so complex, it needed to be plugged into a program built for hydraulic engineers. A professor at Southern Illinois University analyzed the model for us, and we published the results in our story as an animated map. We were the only media outlet to do this.
We showed how the Army Corps fails to re-evaluate projects after they’re built, paving the way for aggravated flooding. We used the Corps’ own post-disaster report to bring accountability to its delayed decision to save Cairo, Ill. from a massive 2011 flood — hesitating to save an impoverished, majority-black city amid lobbying from well-connected farmers who had planted crops in the floodway.