Wonsuck Kim moves from virtual to physical modeling.

Wonsuck Kim moves from virtual to physical modeling.

At the J.J. Pickle Research Campus, a few miles from the main University of Texas campus, Wonsuck Kim is ready to set up a grand, new scientific toy. The Jackson School of Geosciences is funding the construction of a flume tank, a large experimental fluid container that will be roughly the size of half of a volleyball court. Once it’s completed in summer 2010, Kim and his colleagues will be able to fill the flume tank with water and sediment to simulate how shorelines and deltas take form. Consider it the geoscientist’s equivalent to playing in a really big bathtub.

Kim says the tank at the Pickle Research Campus will be one of just three in the world with computer controls that can move and manipulate the unit’s floor to replicate tectonic subsidence and its impacts on river basins.

“I think the Jackson School is one of only a few schools that can support such huge experiments,” says Kim, an assistant professor and a research fellow with the university’s Institute of Geophysics.

Kim started in his career in geosciences in front of a computer. As a master’s student in South Korea, he completed a three-dimensional computational model for sediment transport. The project involved spending two years of reading computer code, and when he was done, Kim was ready for a new challenge—away from a computer.

He found a new spark after he was introduced to physical modeling when he started his doctoral program at the University of Minnesota in 2002.

“Once I saw the physical experiment, I just loved it,” Kim says. “Even a supercomputer cannot model these kinds of things yet.”

Experiments with flume tanks and physical modeling put Kim and others at the controls of geologic simulations. Using basic variables that simulate tectonic subsidence, sea level, and sediment input, scientists can observe patterns, like the migration of shorelines, the infill of deltas, and the morphology, or changing patterns, of stream channels.

The results are a sort of bird’s eye view of these different geologic processes, what Kim refers to as the “evolutionary architecture of sedimentary basins.” The models allow Kim to read the stratigraphy, or rock layering, of a landform, while also applying quantitative methods from computational assessments.

What’s Inside Counts

Previous flume experiments by Kim have produced a “striking” revelation about the role of “autogenic,” or internal, processes, such as river avulsion (the shifting of a stream’s path) or the natural cutting and filling of a valley, on the formation of deltas. Stratigraphic scientists have studied the impacts of “allogenic” forces—subsidence, sediment and sea level—but Kim’s work has demonstrated that the internal elements are essential to correctly deciphering the impacts of forces in sedimentary records.

“One of the very difficult problems we have in traditional basin interpretation using outcrop studies or seismic lines is it’s very hard to distinguish the signature of external forces from internal processes,” Kim says. “We have a lot to do to understand how the autogenic processes are working in delta systems.”

Kim is hoping his tank experiments will help clarify the level of influences from different factors. His work with the new flume tank should produce measurements of the timing and speed of autogenic processes, in a manner we could never observe through field experiments. The results should add to the pool of scientific knowledge on stratigraphy and could have applications for petroleum exploration.

Flume experiments, and their detailed measurements, could also help bridge a division in the field of sedimentology, says Kim. Within the discipline, researchers recognize that siliciclastic (weathered or eroded) materials will form dendritic, or branching, river patterns; formations from carbonate materials will form terraces and cascading dams. Kim is expanding his research with flume experiments to study carbonate sedimentology: He recently has done initial laboratory experiments simulating limestone precipitation in Yellowstone National Park. Once the flume tank is functional at the Pickle Research Campus, Kim wants to model for the emergence and formation of both types of sedimentary structures through tank simulations. The results may even add a new chapter to the sedimentology textbooks.

“I’m very excited about what we can learn from these experiments,” Kim says.

by Joshua Zaffos

For more information about the Jackson School contact J.B. Bird at jbird@jsg.utexas.edu, 512-232-9623.