HYDROLOGIC MODELING AS A PREDICTIVE BASIS FOR ECOLOGICAL RESTORATION OF SALT MARSHES

Roads, bridges, causeways, impoundments, and dikes in the coastal zone often restrict tidal flow to salt marsh ecosystems. A dike with tide control structures, located at the mouth of the Herring River salt mar sh-estuarine system (Wellfleet, Massachusetts) since 1908, has effecti vely restricted tidal exchange, causing changes in marsh vegetation co mposition, degraded water quality, and reduced abundance of fish and m acroinvertebrate communities. Restoration of this estuary by reintrodu ction of tidal exchange is a feasible management alternative. However, restoration efforts must proceed with caution as residential dwelling s and a golf course are located immediately adjacent to and in places within the tidal wetland. A numerical model was developed to predict t ide height levels for numerous alternative openings through the Herrin g River dike. Given these model predictions and knowledge of elevation s of flood-prone areas, it becomes possible to make responsible decisi ons regarding restoration. Moreover, tidal flooding elevations relativ e to the wetland surface must be known to predict optimum conditions f or ecological recovery. The tide height model has a universal role, as demonstrated by successful application at a nearby salt marsh restora tion site in Provincetown, Massachusetts. Salt marsh restoration is a valuable management tool toward maintaining and enhancing coastal zone habitat diversity. The tide height model presented in this paper will enable both scientists and resource professionals to assign a degree of predictability when designing salt marsh restoration programs.