Marsh Erosion and Restoration
Doug Gaffney, P.E., and Mott MacDonald
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.