Marsh Erosion and Restoration

Doug Gaffney, P.E.


Marsh erosion is a complicated process. Erosion and accretion in a marsh cannot be modelled using the same sediment transport based equations as a sandy shoreline. When designing coastal marsh restoration projects, the designer needs to have a framework from which to design. Standard coastal engineering rules of thumb and formulae have to be adjusted or replaced when working in these environments. This presentation will discuss the important features of marshes, how they erode, and methods to reduce erosion and promote accretion through the lens of energy reduction. The concepts of energy transmission, attenuation and structure crest height will be addressed. Low-cost methods of measuring wave energy, and how to apply the results will be presented with three case histories. Case histories include a coastal marsh on the Delaware Bay, a mangrove restoration project in Guyana and an island in Barnegat Bay.

Presented by Doug Gaffney, P.E.

Mr. Gaffney is Mott MacDonald’s Deputy Practice Leader for Coastal Engineering services in the Northeast U.S., focusing on coastal protection, restoration, and resilience. Doug is presently the Environmental Manager for a $750 million design-build tunnel project in Virginia. He has extensive experience in the design of riverine, coastal, and waterfront structures, dredging and marine construction in the U.S. and internationally. In addition to consulting, Doug has worked for the US Army Corps of Engineers as a coastal planner, and as an engineer in the manufacturing sector for products used in water resources projects. Doug is a board-certified Diplomate of Coastal Engineering and is a Professional Engineer in New Jersey and New York. He has a BS in Marine Engineering from the U.S. Merchant Marine Academy and a M.S. in Applied Ocean Science from the University of Delaware.