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| NCED Geomorphic-Dynamics Working Group Meets | | The fourth meeting of the geomorphic-dynamics working group occurred in Doolin, Ireland, last month. This NCED working group meeting, cosponsored by NCED, the British Engineering and Physical Science Research Council, and the University of Limerick, focused on developing mathematical and numerical models for describing delta growth (e.g., Wax Lake Delta, Louisiana). Currently, NCED PIs and colleagues have developed a number of mass balance delta land-building models. These models successfully capture the average features of the land-building stage in deltas and have contributed significantly to understanding physical experiments and field cases. However, these models do not resolve the channels in the system and cannot account for the local off-shore building processes or the occurrence of avulsion events. The central objective of the current working group was to develop models and modeling devices that could correct these deficiencies. The participants at the meeting made significant progress in two areas: (1) a simple mathematical model was developed to describe the off-shore channel building processes, in particular the creation of levees and mouth bars, and (2) a combined rule-based model and finite element model, with the capability of creating channels within a mass balance delta building model, was initiated. Work will continue in these areas, and the working group will meet again in late July 2008 at the Woods Hole Oceanographic Institute in Massachusetts. |  | Left: The figure shows a preliminary delta land-building simulation—carried out by graduate student Man Liang. This simulation constructs the channels (blue lines) as the calculations proceed. The simulation results can be qualitatively compared with the Wax Lake Delta. Right: A view of the Wax Lake Delta, Louisiana.
| | | | | | Making Tradeoffs in the Mississippi River Delta | | Without significant human intervention, the Mississippi River Delta would be a sustainable system where land is built through sediments deposited by the river and lost due to subsidence. However, since the 1930s, approximately 1.2 million acres of land have been lost: the amount of sediment delivered to the delta has decreased (due to dam construction) while sea levels have risen. Restoration of the Mississippi River Delta will provide unique ecological, economic, and social benefits. To aid in this effort, NCED Postdoc Melissa Kenney and NCED PI Ben Hobbs are developing methods to evaluate various wetland and barrier island restoration alternatives by considering tradeoffs among restoration objectives (such as flood protection, salt and fresh water fishing, navigation, and land building). By collaborating with NCED PIs Robert Twilley, David Mohrig, Chris Paola, and Gary Parker, Kenney and Hobbs hope to provide methods that help government agencies and stakeholders make more informed choices about how best to restore the Mississippi River Delta. | | NCED at the NABS Annual Meeting | | NCED PI Jacques Finlay, along with former NCEDians Mark Green and John Schade, is co-organizing a special session entitled, “Ecological stoichiometry of catchments: Scaling our understanding of physical, chemical, and biological controls” at the North American Benthological Society (NABS) 56th Annual Meeting. In addition, current and former NCEDians Cailin Huyck Orr, Mike Limm, and Ben O’Connor are co-organizing another NABS special session: “Integrating biological/biogeochemical measurements with complexity in hydraulics and geomorphology in streams.” Several more NCEDians are giving presentations during these sessions. View the complete list of special sessions and supporting talks at the NABS Annual Meeting. | |
