Marcelo H. García

Marcelo García likes water and sand.  He enjoys being able to step out of his office to check on ocean and river current experiments—even though the University of Illinois is several hundred miles from a major river and nearly a thousand miles from an ocean.

His research is conducted in the Civil and Environmental Engineering Hydrosystems Laboratory.  He can trace his academic lineage of advisors back to Lorenz G. Straub, a 1927 U of I graduate known as the "River Doctor."

"Now I've become a 'river doctor' in a way, and it's interesting that I came here—very special," he said.  "I never imagined that I'd become a U of I professor, but I didn't think twice when the opportunity came my way."

García is the Chester and Helen Siess Professor of Civil Engineering and was named a University Scholar in 2000. 

His fascination with water research started in his 20s, when he was assigned to a hydraulics lab where scientists were conducting modeling experiments in preparation for constructing a dam in the Paraná River, Argentina.  His research addressed a concern that erosion of river bottom clay could undermine the foundation of the dam.  

"The experience showed me that I could do very good engineering and at the same time do the research needed for engineering," he said.  "That idea has followed me.  I enjoy research and science and teaching—my work here brings all that together."

One of his greatest challenges has been to map a direction for the Hydrosystems Lab, which was inactive when he arrived on campus a decade ago.

"I could see the potential," García said.  "Now, we are not the largest in terms of size, but we can do unique, large-scale experimentation within the confines of the lab, as well as complex, three-dimensional computational modeling.  We are doing research not done in other places."

One example of unusual research equipment is a tank that allows researchers to study ocean currents by recreating conditions found at a continental shelf.  A better understanding of how these shelves are built over time benefits marine biologists.  In addition, geologists can use the information to narrow their search for oil.

Other equipment in the lab is used to recreate flows that occur as barges move through large rivers.  Disturbed sediment that suspends in the water can have a negative impact on biota and is especially hard on small fish.  Researchers can study a variety of river problems, including how to move canoe and kayak enthusiasts through the dams more safely.  That research yielded a design for canoe chutes—a series of steps that could be erected on existing spillways—which is being considered by the Illinois Department of Natural Resources.

Another special piece of equipment uses a belt in one of the water chambers to create an environment for studying stratified flows, such as a wedge of water moving from one water source into another.  García used this equipment to study the flow of saline water into the Mississippi River, which can interfere with the fresh water intake for New Orleans.

Closer to home, his team is investigating the formation and movement of density currents from the North Branch of the Chicago River into the main stem of the river.  Under some circumstances, such currents could create a water contamination hazard in the river and Lake Michigan.  Being able to predict the frequency and circumstances of the density current will help state officials manage gates and pumping stations for water diversion from Lake Michigan.

"There are many interesting applications for our research," García said.  "It is very important to understand what is happening under the surface of the water in order to make decisions about water use and ecology."

Many of García's studies combine experimentation and modeling.  One example is a project aimed at assessing the effectiveness of coarse-bubble diffusers for controlling oxygen levels in wastewater.  Bubble plumes can be created by pumping air through pipes with a series of holes.  Equipped with valves, these pipes can be used to create bubble plumes.  Yet unknown are whether the bubble plumes are practical in terms of energy expense and what effect the plumes will have on biosolids and sediment.  The research group is conducting small-scale flow studies in the laboratory and modeling different scenarios for a half-billion-dollar Chicago-area waste treatment project.

In addition, large-scale experiments are under way in a 45-foot diameter tank managed by the Urbana-Champaign Sanitary District (USCD).  The bubble plumes that will be created in the tank were analyzed in an earlier phase of research.  García's group developed a 3-D hydrodynamic model and took advantage of the computing power of the Linux cluster, "Los Lobos," in New Mexico.

"The USCD tank offers a fantastic opportunity to measure biochemical oxygen demand, which we couldn't do in the lab," García said.  "Someone has estimated $80 million for an oxygenation system in Chicago, so anything we can do to get a realistic analysis could mean potentially major savings for taxpayers."

New research in the lab will use innovative U-tubes to recreate conditions found at the bottom of the ocean.  Pistons will push water back and forth, allowing researchers to study sediment movement and other seabed mechanics.  This research could address safety issues related to oil pipelines or help the Navy understand what happens to mines on the ocean floor. 

One U-tube, which is under construction with the help of a Defense University Research Instrumentation Program grant, will be unique in the world.  The U-tubes add yet another unusual element to a laboratory that now attracts researchers and students from around the world.  García typically has nearly a dozen graduate students as well as a few undergraduate students working on projects each semester.    

"By the time they walk out of here, students know how to do research.  That puts them in a special position, whether they go on to graduate schools or to jobs," García said.  "In the field of sedimentation engineering and environmental hydraulics, we are working on cutting-edge problems and issues that have immediate impact.  Our research offers a tremendous opportunity for students to work on something important.

"What we do improves the quality of the environment and ultimately, the quality of life for everyone."

—Tina M. Prow