By Kathleen Berger, Executive Producer for Science and Technology

Johnson’s Shut-Ins is one of Missouri’s premiere swimming holes, with water cascading through billion-year-old rocks, creating the pools, chutes and waterfalls. It’s a great summer getaway that’s not far away!

“It’s one of everybody in Missouri’s favorite places to go and recreate,” said Claire Masteller, Assistant Professor of Earth and Planetary Sciences at Washington University in St. Louis.

And Johnson’s Shut-Ins is not too far for Masteller to study! She’s a geomorphologist.

“I like to describe geomorphology as the science of scenery,” she said. “Here in Missouri, we get a lot of rainfall in the spring. And so, we’re interested in how the floods that run through our rivers in the springtime might act to change their shape or might cause some overflows and flooding.”

At Johnson’s Shut-Ins, Masteller’s team is focused on flooding and bedrock river erosion.

“It’s called a shut-in because where that hard, resistant bedrock meets the surface, the river has to get really narrow and really steep and create these rapid formations to sort of plow through that solid rock,” Masteller explained. “It’s a bedrock river. It’s really energetic!”

Masteller is engaged in collaborative research focused on shifting rivers and changing landscapes from flooding and erosion that happen with climate change.

“We’re interested (at Johnson’s Shut-Ins) in understanding how those full bedrock features erode and change through time,” she said.

The research team is using different tools, like a flume in Masteller’s lab, so they can conduct experiments without risking their safety when flooding occurs.

“That’s where the (lab) experiments really come in handy, right? Because we don’t have to wait around for climate change to happen.”

So, Masteller and her students don’t need to go to the river during a major flood event for research, because they can create the force of floods through the flume in her laboratory. In HEC Media’s video story, Masteller sets the flow of water as high as 160 gallons per minute to 190 gallons of water per minute.

“You really care about when this stuff (the gravel) starts to move,” Masteller explained. “When the gravel starts to move, you’re doing the work of erosion that’s changing the landscape.”

The contents of the flume change for Johnson’s Shut-Ins experiments.

“Instead of filling it with gravel, we can put bedrock blocks in it. And we can have gravel bounce on top of the bedrock,” she said. “We can measure how that bedrock erodes.”

Other technologies are deployed on location.

“Seismometers can feel the vibrations of the water as it flows through the river. So, we can really get a high-resolution record of all the flooding and erosion there. And what that allows us to do is avoid the dangerous aspects of trying to get into a river while it’s flooding. We can record those vibrations of that rushing water or the grains of sediment bouncing against the rock, and we can use that record instead to interrogate what’s really happening during a flood.”

The seismometers are strategically placed and the data is routinely retrieved for analysis.

“We have three different ones placed in three very different parts of Johnson’s Shut-Ins. We like to get as close to the river as possible without being in the flood zone. So, I think they’re about 30 feet away, in two of the cases,” Masteller said. “And then where our rapids are, we have them a little bit further away just because of access. We actually go there every month or two and we download our data and then look at how the topography changes.”

The lab is using geospatial technology for gathering topographic data generated by a LiDAR drone.

“We go out and use unmanned aerial vehicles, UAVs, to take laser scans of the river before and after these floods and try to get a sense of how they’re changing.”

The topographic scans combined with repeat photos and seismic wave velocity measurements allow researchers to measure the effects of different erosive processes at Johnson’s Shut-Ins. As the work continues, the flume is proving to be a valuable asset.

“Like to go and find places where we can go out and take measurements. But sometimes, like during a flood event, it’s actually really dangerous.”

Masteller’s students continue to pair the flume experiments with data from Johnson’s Shut-Ins and the lab engages in studies of other rivers in Missouri.