June 10, 2002--Every year, more than one million tons of sediment–approximately 100,000 dump truck loads of mud–is washed into the Delaware Estuary, which stretches 134 miles from the Trenton falls to the mouth of the Delaware Bay between Cape May, N.J., and Cape Henlopen. Some of this sediment accumulates in the fringing marshes, and some of it settles to the river bottom.

Christopher Sommerfield

Because the sediment is a moving target, sediment transport is difficult to study. Nevertheless, an understanding of this process will provide information on the natural evolution of the estuary, the impact of human activities, and the mechanisms by which sediment and any associated pollutants move. This information is central to resource management issues in the Delaware Estuary.

Christopher Sommerfield, assistant professor of oceanography at the University of Delaware, will discuss the natural and human influences on estuarine sedimentation in a talk titled “Delaware River Mud Reveals Its Dirty Secrets” at 7 p.m., Thursday, Aug. 22. The presentation is part of the Ocean Currents Lecture Series, which is held once a month at the Lewes campus through September.

“Geologic and oceanographic processes have created the Delaware Estuary over thousands of years,” Sommerfield says. “Proper management of the estuary requires that we understand these processes, as well as human impacts of the past two centuries. New seafloor mapping technology is helping in this regard.”

After providing a brief explanation of how estuaries are formed, Sommerfield will describe how human activities can change the natural balance of these systems. For example, bulkheading reduces the exchange of sediment between the estuary’s tidal flats and marshes, which can lead to long-term erosion.

In addition, the Delaware River is regularly dredged by the U.S. Army Corps of Engineers to maintain access to the largest freshwater port system in the world. Dredged channels can change the flow of water within an estuary, which can have a major impact on natural sedimentation patterns.

Sommerfield will conclude his talk by presenting results of a study conducted by his research group to image the river bottom from Burlington, N.J., to New Castle, and create new maps of sediment types. The maps are guiding the efforts of local environmental agencies to develop a computer model of sediment deposition in the estuary.

Prior to joining the UD faculty in 2000, Sommerfield was a postdoctoral scholar at the Woods Hole Oceanographic Institution in Woods Hole, Mass. He received his bachelor’s degree in geology from West Chester (Pa.) University and his master’s and doctoral degrees in marine environmental sciences and coastal oceanography, respectively, from the State University of New York at Stony Brook.

The lecture will be held in Room 104, Cannon Laboratory, at the Hugh R. Sharp Campus, 700 Pilottown Road, Lewes. The hour-long talk will be followed by light refreshments.

While the lecture is free and open to the public, seating is limited and reservations are required. To reserve a seat, please contact the college at (302) 645-4279.