Stream of Consciousness: Kevin Roche

by Sean Hargadon

Working in Limón, Costa Rica, as a Peace Corps youth development volunteer, Kevin Roche saw the jarring contrast of environmental degradation in an ecological paradise. Packed buses that ferried tourists to biological reserves drove past rivers contaminated by raw sewage. 

At Northwestern, Roche studies how that contamination moves in rivers and streams, specifically in hyporheic zones, the thin layer of sediments between the surface waters and groundwater. Just a few centimeters to several meters in thickness, the zone is home to bacteria, fungi, macroinvertebrates and other organisms. “There’s this constant exchange between the river and the groundwater that we don’t see and for a long time we ignored,” he says. “We now know it plays a major role in how contaminants move and react in rivers.”

Roche, of Highland, Ind., uses the example of agricultural runoff in the Midwest. After a big rain, fertilizers are flushed from land into rivers. In the sediments, “there are small microorganisms that are actually consuming these nutrients.”

Roche is conducting experiments and developing models to predict what’s happening in those subsurface sediments. He hopes his research provides evidence for making land management recommendations. He is focusing primarily on gravelly sediments. In the Technological Institute, Roche uses a network of sensors in the bed of a 2.5-meter artificial stream — a “glorified gutter” — to measure how fast dissolved chemicals are exchanging between the surface and the subsurface.

“If we want to understand our impact on rivers, streams and lakes and we want to understand how we could better manage them, not only in today’s climate but in a situation where the climate or land use might change, then we need to have a better understanding of how things move and react in rivers,” he says.

Roche, who studied chemical engineering at Purdue University and worked as a process control engineer at Eli Lilly in Indianapolis before joining the Peace Corps, plans to begin a postdoctoral research position at the University of Notre Dame after graduating with his doctorate in civil and environmental engineering in August. 

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