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Civil and Environmental Engineering

Jessica Guo and Sasanka Gandavarapu

Jessica Guo (left) and Sasanka Gandavarapu (large image)

Civil and Environmental Engineering

Bridge between transportation
and health could be
in the bike lane

Assistant Professor Jessica Guo hopes to give city planners the tools to make fiscally responsible, neighborhood-level decisions that reduce vehicular traffic and also improve public health. “Our focus is really more about identifying win-win solutions that would take people out of their cars and have them use more of the walking and biking mode,” she says.

In particular, Guo is interested in non-commuter travel, which constitutes up to 70 percent of all daily travel. “The non-commuter trips are contributing a lot to pollution and congestion throughout the day and on the weekends,” she says. “Yet, these trips tend to be short—and therefore represent good opportunities for the travelers to improve their fitness if they bike or walk.”

With colleagues at the University of Texas at Austin, Guo analyzed San Francisco Bay-area residents’ personal travel diaries and related their non-commute travel habits to such neighborhood characteristics as population density, percentages of residential and commercial land use, number of businesses, roadway density, street connectivity, and others. In addition, she also studied how travel decisions and modes varied across different population segments. For example, for most population groups, mixed-land use discouraged driving; however, it increased vehicular trips among single parents and people in households with multiple vehicles.

After analyzing personal travel data from other areas of the country—including Dane County, Wisconsin, with master’s student Sasanka Gandavarapu—Guo hopes to identify commonalities among each population segment. She will use those patterns to develop general guidelines for city planners and engineers throughout the country. Because most previous studies examined aggregate—rather than personal—travel behavior, Guo says one plan to modify the built environment might not work for everyone.

“We have to make sure that, whatever we do, we are meeting the needs of the residents in that neighborhood while offering environmentally friendly and health-promotive alternatives,” she says.

Freeing underground oil, with water

Although world demand for oil is increasing, some estimates indicate that crude oil output has hit a plateau at 85 million barrels a day and, within a few years, will begin to decline. “We are reaching a capacity as to how much oil we can get out of the ground,” says Assistant Professor Dante Fratta. “But when we pump, we leave about 50 percent of the oil in there.”

Like the greasy post-dinner buildup on a kitchen stove, much of that remaining oil coats the rocks and minerals in an oil field. “In some formations, the oil gets attached to the surface, and it’s difficult to remove,” says Fratta.

With Geology & Geophysics Professor Herbert Wang and Universidad Nacional de Córdoba (Argentina) Assistant Professor Franco Francisca, Fratta is developing an enhanced oil recovery method that uses salt water as a wedge to “scrape” oil away from the porous, uneven underground surfaces. Their method exploits the power of a technique called electrowetting.

Using their technique, the researchers would inject a detergent-saltwater mixture into the oil reservoir, then apply a low voltage to sensors placed throughout the oil field. Both the voltage and detergent reduce the surface tension of the water droplets, essentially flattening them and turning them into wedges that can release the oil. “So you have an oil drop, and you force the water to go in between,” says Dante Fratta.

While the researchers have shown that the technique works in the laboratory, their next challenge is figuring out how to implement it in the field.

Returning to our roots:
Watershed study solidifies science
behind ecosystem restoration projects

Working with The Nature Conservancy in Wisconsin and the state Department of Natural Resources, a pair of hydroecologists is evaluating the efficacy of an ecosystem restoration project along a stretch of the Pecatonica River in southwest Wisconsin. Results of their research could apply to similar watershed restoration initiatives around the country.

In southwest Wisconsin—undulating, unglaciated terrain known as the Driftless Area—170 years of farming and grazing in the region has flattened former prairies and oak savannahs and eroded hill slopes, resulting in sediment runoff into streams.

“When you have this different surface—the agriculture on the upland, contributing more water to the valleys—you have more floods, and with those floods, you have a lot more sediment in them,“ says limnology PhD student Eric Booth, who, with Assistant Professor Steven Loheide, is studying the area.

Over time, floods carried sediment over the Pecatonica floodplain, depositing it on the land. The sediment buried former wet prairies and sedge meadows, building up the watershed and triggering ecosystem changes driven by the rising land surface.

“What you’re left with now is a floodplain surface that’s much further from the water table, and it’s drier without the sedge meadow and wet prairie,” says Booth. “You also have cropland and grazing on the floodplains.”

For the restoration project (funded through state wildlife action grants), crews “scraped” about 12,000 cubic yards of topsoil—years of deposited sediment—from about 20 acres of floodplain. A year later, heavy rains showed that the restored site effectively reduced the velocity of floodwaters through the river and gently spread the excess over the floodplain, lessening erosion and encouraging sediment deposition. Now the restored area also provides increased habitat for wildlife and amphibians.

Currently, Booth is monitoring the site to quantify the hydrologic and vegetative effects of the project. Ultimately, he hopes to translate his field data into a computer model that will enable watershed managers to predict the ecological effects of the changes they make.

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