University of Delaware
Chris Sommerfield, who conducts research on Delaware’s estuaries, is among recipients of an NSF grant on sustainable urban estuaries.

Sustainable estuaries

NSF grant supports research on sustainable urban estuaries


1:35 p.m., Dec. 11, 2013--Altering waterways — from deepening rivers to paving over wetlands — has helped port cities thrive over the past century. Yet the changes can disrupt nature’s ways of dealing with coastal storms, as seen in New York last year after Hurricane Sandy.

“When you deepen an estuary, you basically reduce its capacity to buffer the impacts of extreme tides and storm surge,” said Chris Sommerfield, associate professor of oceanography in the University of Delaware’s College of Earth, Ocean, and Environment (CEOE). “Some people think that Hurricane Sandy had more of an impact in New York City than it would have before the harbor was deepened and the wetlands filled.”

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Sommerfield and George Parsons, professor of marine policy, are studying the changing shape of urban estuaries over time as people modify them to meet societal needs, including ports and harbors to accommodate ships of increasing size. The researchers received National Science Foundation (NSF) support in collaboration with colleagues from Woods Hole Oceanographic Institution, Rutgers University and Drexel University for a five-year grant totaling $2.8 million.

The funding is provided through NSF’s Coastal Science, Engineering, and Education for Sustainability (SEES) program, which supports interdisciplinary research and education focused on the sustainability of coastal systems according to a recent announcement of 11 grants. 

The project that UD researchers are involved with will examine the physical, ecological and socioeconomic aspects of man-made changes in estuaries, such as construction of shipping channels and hardening shorelines.

This will involve investigating indirect effects and cumulative impacts of these changes on environmental flows and ecosystem services. The researchers define “sustainability” as meeting today’s demands for estuary use while not compromising the needs of future generations.

“We really need to meet a balance between human needs and the ecological requirements of estuaries,” Sommerfield said. “We believe that urban-impacted estuaries can be managed in sustainable ways that provide services to coastal populations while maintaining ecosystem functions.”

The team, which will include several graduate students, will focus on areas where the Delaware, Raritan and Hudson rivers meet the Atlantic Ocean along the coasts of Delaware, New Jersey and New York. These river-estuaries have a long history of human modifications related to urbanization, industry and marine transportation. 

On the socioeconomic side, Parsons and CEOE alumnus Porter Hoagland, now with Woods Hole Oceanographic Institution, will identify the ecosystem services that the estuaries provide. Examples include ship navigation, safe drinking water, storm protection, bird watching, hunting and commercial and recreational fishing.

Using various economic models, the value of such ecosystem services can be given dollar amounts. In a previous Delaware Sea Grant analysis, for example, Parsons estimated the economic value of bird-watching along Delaware Bay.

Then, the social scientists will consider the trade-offs associated with different engineering practices. For example, there is a societal benefit of deepening rivers to allow larger ships through and facilitate trade, Parsons explained. However, removing water-absorbing wetlands can make for increased threats of damage from coastal storms and rising sea levels.

“Economics is about finding balance between competing uses for resources,” Parsons said. “We’re trying to understand the tradeoffs and find that balance in this project.”

From the environmental perspective, Sommerfield and other coastal oceanographers on the team will look at the physical changes that have taken place in the estuaries and wetland coasts from the middle 1800s to present. Removing mud to deepen channels alters the way water and sediment flow, in turn changing the estuary size and shape — or morphology — further.

How past modifications impact present-day conditions will be addressed using a combination of historical bathymetric data, numerical modeling of estuarine processes, and observational studies of water and sediment transport. 

“We’re investigating incremental effects that usually go unnoticed but which on the long term have cumulative impacts on how estuaries function,” Sommerfield said. 

For Sommerfield, the project builds on years of estuarine research supported by Delaware Sea Grant. In partnering with social scientists, the team will form a picture of human-environment interactions in the past and how management decisions may affect the future. The researchers intend to work with policy professional at local, regional and federal levels. 

“The science and policy team members are all working together closely on the same problem  sustainable urban estuaries  but from different perspectives and using different research approaches,” Sommerfield said. 

Article by Teresa Messmore

Photos by Kathy F. Atkinson and Danielle Quigley

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