NOAA'S Role In Tidal Marsh Restoration: A Look At Barren Island

Craig Martin
Center for Operational Oceanographic Products and Services (CO-OPS), NOS


Tidal wetlands are extremely valuable economic, cultural, and aesthetic resources, yet they are under the constant threat of degradation and decline. One such area in decline, Barren Island, is a mid-Chesapeake Bay parcel island in the U.S. Fish and Wildlife Service’s (USFWS) National Wildlife Refuge System. Its hydrodynamically-complex regime has complicated restoration efforts. Small-scale demonstration beneficial use projects have been conducted on the site, using geotextile tubes for onshore protection, with dredge material being placed land-side to re-establish tidal and lowland marsh habitat where vegetation has been and will continue to be planted through citizen participation. The site is subjected to coastal erosion due to tidal currents and wave action, thus it was critical that water levels, currents, and waves were analyzed to ensure the stability of the restoration project. Use of tidal datums, traditionally recognized for their importance to hydrographic surveys, shoreline mapping, and determining baseline boundaries, have been vital in ensuring successful marsh restoration efforts. Tidal datum elevations are determined relative to the present and future marsh surfaces by establishing a tide station with local bench marks which were connected to geodetic datums via leveling and/or GPS techniques, thereby establishing a vertical reference frame for the datums to be depicted onto Digital Elevation Models (DEMs). This procedure also enables the rising and falling of tidal levels to be referenced to the marsh substrate. Analyses of water heights and long-term sea level trends are essential for proper coastal engineering and biological planning of tidally-influenced marshes. Use of GIS visualization and analyis techniques will help future planners display and understand previously unrelateable components of tidal marsh restoration.