GLOBAL CHALLENGES

New Tech to Predict Soil Erosion, Prevent Bridge and Building Collapse

Rebecca Kutzer-Rice | Date: 11-17-10 | Comments

Newly developed technology will help determine the strength of infrastructure before and after storms�thereby predicting soil erosion, preventing building and bridge collapse, and saving lives.

Much of the disaster brought by Hurricane Katrina was caused by soil erosion, or scour, which led to the collapse of bridges and the failure of crucial levees. A new sensor developed by researchers at North Carolina State University will allow engineers to predict the possibility of soil erosion due to water flow�thereby preventing and lessening a wide range of critical infrastructure breakdowns.

More than half of all bridge collapses are caused by soil erosion (source: Sid Brown, Schenectady Gazette).

Current technologies do not allow scientists to adequately monitor erosion, which has been linked to approximately 60 percent of bridge failures in the United States. In 1987, for example, the Schoharie Creek Bridge collapsed in New York due to scour. Ten people were killed in the disaster.

The new device, called the "In Situ Scour Evaluation Probe" (ISEP), is the first of its kind, allowing engineers to track erosion immediately in the field.

"The ISEP is the first technology that allows technicians in the field to measure the scour potential of soils without the need for excavation," said Dr. Mo Gabr, a professor of civil, construction and environmental engineering at NC State, and co-author of a paper describing the new device. "Previous technologies required engineers to take samples and process them in a lab."

The new probe will allow engineers to more accurately predict soil erosion and protect vital infrastructure (source: North Carolina State University).

Using a water jet, the new device digs a hole into the soil. Engineers can use the sensor to track how quickly water can displace a certain soil sample. The device can also change velocity and flow rate to imitate various natural weather conditions, from light rain to hurricane-strength surges.

"The ISEP's ability to measure scour potential at different depths helps us predict how the soil will behave in the future as a support media, as various layers of soil are eroded or scoured," Gabr says.

The scientists hope that the ISEP's ease of use will encourage federal and state agencies, as well as private organizations, to perform erosion assessment tests more frequently. Since the device requires no external lab testing, it will likely be less expensive to use than traditional assessment methods. The NC State researchers note that more testing means more data, and therefore more accurate predictions about soil behavior.

In November, the scientists will use the device to analyze dune erosion in North Carolina's Outer Banks.

The ISEP, which was described in a paper presented at the 5th International Conference on Scour and Erosion in San Francisco, received funding from the U.S. Department of Homeland Security (DHS) as part of its Center of Excellence on Natural Disasters, Coastal Infrastructure, and Emergency Management program.