Volume 13, Number 2, 2005
Some visitors to the seashore may see a tranquil spot to relax and watch the waves roll in, while others see a treasure trove of shells to collect, a pleasant place to swim or a surf-fishing opportunity.
Jim Kirby sees an engineering challenge.
Kirby, Edward C. Davis Professor of Civil and Environmental Engineering, conducts research through the College of Engineering’s Center for Applied Coastal Research and the Delaware Sea Grant program. He and a team of colleagues from nine other institutions around the country are finishing up an extensive, five-year research project funded by the National Oceanographic Partnership Program to study how waves behave.
In the project, the researchers have developed and tested a comprehensive computer model designed to predict a variety of physical processes in the nearshore ocean—the area from the high-tide mark on the sand out to a depth of about 10 meters. The model considers such properties as wave heights, current movement and sediment transport, which occurs as the movement of the water carries sand from one spot to another.
Each property is influenced by a complex assortment of factors, Kirby says, meaning that researchers can realistically hope to make predictions hours or possibly days—rather than weeks or months—in advance. The model that has been developed will be made available via the Internet to researchers around the world, who are expected to continually test, refine and expand it.
“As a physical scientist, my interest is in understanding basic processes in the natural world,” says Kirby, whose background is in fluid mechanics and who initially was interested in meteorology before turning his professional attention to coastal engineering. “But, these studies often lead to development of numerical prediction tools, which are then available for design-oriented engineers to use.”
He says the predictive tools he and his colleagues have developed could be useful for anyone building houses along the coast, constructing a pier or dredging for a marina. “For example, if you’re building a pier, you’d want to know the range of wave heights that it would be subjected to,” Kirby says.
In addition, being able to predict the dangerous water movements known as rip currents could be vitally important to swimmers and lifeguards. A rip current, sometimes incorrectly called an “undertow,” is a narrow, powerful current of water running perpendicular to the beach, which can unexpectedly pull swimmers from shallow water out into the deeper ocean. Rip currents are responsible for more than 100 deaths annually in the United States and are a factor in about 80 percent of all surf rescues, according to water-safety experts.
“In terms of natural hazards, rip currents are extremely dangerous,” Kirby says. “We’d like to be able to reliably tell a lifeguard crew how dangerous a particular section of beach is at any given time.”
The deadly Dec. 26 tsunami, caused by an earthquake in the Indian Ocean, is of professional interest to Kirby, who says he hopes to receive data from that event and review it using similar technology to that of the nearshore modeling project. But, he adds, the nearshore project isn’t designed to study wave activity at the intensity of the tsunami, which devastated large areas of south Asia.
The other UD researchers involved with the nearshore modeling project have been Ib A. Svendsen, Distinguished Professor Emeritus of Ocean Engineering in the civil engineering department, who died Dec. 19, and Fengyan Shi, associate scientist in the Center for Applied Coastal Research. Dr. Svendsen, who held a joint appointment in the College of Marine Studies until his retirement in August 2004, conducted pioneering research in the area of wave movement, wave-induced currents and the turbulence caused by breaking waves.
The individual researchers worked relatively independently through the course of the partnership, Kirby says, with UD managing the code development for the computer model.
“What has made it a centralized project is that we have tried to integrate all the modules into a systematic, centralized program,” he says. “Then, our hope is that different researchers will tie into this community model and not only use it but also add to it and extend it.”
The National Oceanographic Partnership Program, a collaboration of 15 federal agencies, was established in 1997 to provide leadership and coordination of national oceanographic research and education programs.