University of Delaware Office of Public Relations The Messenger Vol. 5, No. 1/1995 Center creates rip currents Last summer, while turbulent riptides kept many Delaware beach-goers sitting on the sand, Robert A. Dalrymple, professor of civil and environmental engineering, and Ib Svendsen, chairperson of that department, were busy creating their own rip currents in the Center for Applied Coastal Research on the Newark campus. The once flat-bottomed 60- by 60-foot wave tank at the center now boasts a new slope to simulate a beach. In the future, several moveable concrete sandbars will be added to the beach- arranged at different locations as the researchers study changing currents and ocean phenomena. Sandbars, which traditionally build up during heavy storms, cause rip currents by channeling water into narrow cross-shore flow patterns. The resulting current can be so sudden and so fast that even the most experienced swimmer can be caught. Now that this year's drought and resulting water restrictions have eased in Delaware, the researchers plan to blast waves at the sandbars in all sorts of patterns created by 34 wave paddles that cause motion in the directional wave basin. Work at the wave tank is one of several aspects of a large research project that began in October 1994 and will continue until 1997 with funding from the U.S. Office of Naval Research. In addition to Svendsen, who is the project director, and Dalrymple, researchers from Seattle, Wash., and Monterey, Calif., are involved in the $750,000 project. Studies of wave motion inside the surf zone (close to shore) are important to the U.S. Navy when it comes to landing troops, Dalrymple says. Another important aspect of the project is the computer modeling that will be tested against the gathered data. There is a limit to the amount of on-site information that can be gathered, Svendsen says, as it is always impossible to predict what patterns the water is following outside a measured area. Computer projections can fill in those gaps, allowing researchers to predict what may happen to the water between on- site measuring points. Long term, the study could result in information that would be helpful in beach management, perhaps to assess the economic risks in a certain area or to predict what could happen to a beach under certain weather conditions. Svendsen and Dalrymple say this research is a natural outgrowth of work that has been ongoing at the center for many years. "As our field has expanded over the years, there are more and more sophisticated questions out there," Dalrymple says. The Center for Applied Coastal Research, which has been in operation for six years, involves four faculty members, more than 20 graduate students and visitors from abroad. -Beth Thomas