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
     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
     "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