After removing six tons of sand and plugging the leaks, the student team spent four more days refilling the sand.
Published March 21, 2013
The work wasn’t glamorous, but it had to be done.
Last November, UB master’s student Ethan Mamer removed 6 tons of sand—by hand—from a 10-meter-long (33-foot-long) artificial river he was using to study how water cycles through streams. He needed to empty the river to repair leaks in silicone caulking that were affecting experimental results.
“It took some thought as to how I was going to get all the sand out and where I would put it,” Mamer says. “We toyed with the idea of getting a giant moving dolly, a complicated pulley system and another couple of plans that were all a little crazy.”
In the end, he settled on simpler tools: shovels, 55-gallon barrels and a lot of muscle. The job took five days. Several students in Mamer’s department, geology, took pity on him and volunteered to help. Then, in January, after plugging the leaks, the team spent four more days refilling the sand.
Mamer ran another series of experiments. They worked. He was euphoric.
Welcome to the world of river restoration research.
Though scientists in the field spend countless hours studying real-life streams, scale models made from lumber and PVC pipes also play an important role in helping investigators understand rivers.
At UB, scientists are using such devices to test techniques for strengthening riverbanks and to simulate groundwater discharge in streams—a process that plays a role in removing nitrogen pollution and supporting wildlife.
These model waterways, called flumes, are awesome apparatuses that feature flowing water and elements customized to meet the needs of research projects. They require maintenance—as Mamer discovered—but the science they support is important.
Mamer and Chris Lowry, assistant professor of geology, are working with a flume in the basement of the Natural Sciences Complex, North Campus.
This flume pipes water into a thick bed of sand to simulate how groundwater bubbles up to the surface of streams. Heat-sensing fiber-optic cables run through the flume, providing Mamer with temperature measurements that he uses to determine how groundwater, which is cool, is rising and mixing with warmer surface water.
The body of the flume is a 5-meter-long rectangular box, but a divider runs lengthwise down the center, doubling the length of the artificial river to 10 meters.
Mamer and Lowry recently completed a series of experiments using the flume to model how groundwater and surface water interact. This work enables the scientists to verify their field results and improve techniques for locating groundwater hotspots in real rivers—important information for stream restoration.
“In zones where groundwater is discharging, you have more invertebrates, which are a food source for fish like trout,” says Lowry, Mamer’s faculty adviser. In addition, the cycling of water from the surface of a river into the ground and back can help remove nitrogen pollution, which enters streams as agricultural fertilizer runoff.
Another research team of Donghua Cai, an MS student in geography; Michael Gallisdorfer, a PhD student in geography; Seyed Mohammad Ghaneeizad, a PhD student in civil, structural and environmental engineering; Sean Bennett, professor of geography; and Joseph Atkinson, professor of civil, structural and environmental engineering, is working with a flume in Statler Commissary on the North Campus.
This flume is a 7-meter-long and 2-meter-wide scale model of the Big Sioux River in South Dakota. Using a battery of instruments that slide along movable guiderails, the scientists can measure the volume and speed of water flowing through the flume, along with the forces that the water exerts on structures placed inside the flume.
The “river” drains into a large plastic basin where it’s then recycled—pumped through white PVC pipes back to the top of the apparatus. On a recent afternoon, water was moving through the flume at a rate of 425 gallons per minute.
Placing formations of engineered log jams into rivers can protect stream banks from the erosive forces of flow, and Bennett and his team are studying which formations work best: “What should they look like, where should they be placed and what should be their frequency in space?” he says.
To test different stabilization structures, the researchers place models of the structures into the flume and track how their presence affects turbulent flow, fluid forces and bed topography.
The team’s findings will help scientists working with the city of Sioux Falls and the South Dakota Department of Environment and Natural Resources make decisions on how to stabilize the real Big Sioux River, Bennett says.
Ghaneeizad says one of the most exciting parts about the flume work is that it will yield real-world results. “This is a project that will be used somewhere in the United States. The results will help someone—it’s not just a library project,” he says.
Both flumes were built by the Instrument Machine Shop in the College of Arts and Sciences.