PHASE 2 - Inventory of Storm-Induced Habitat Modifications to Tidal Inlet and Sandy Beach Habitat Caused by Hurricane Sandy (November 2012)
Tidal inlet and sandy beach habitat have been modified throughout the entire U.S. Atlantic Coast breeding range of the piping plover (Charadrius melodus), from Maine to North Carolina. Inlets and sandy beaches are highly valuable habitats for piping plovers, red knots, other shorebirds, and waterbirds for nesting, foraging, loafing, and roosting. The North Atlantic LCC has designated the piping plover as a representative species in all three subregions, standing as a surrogate for other species using dynamic beach systems including American oystercatchers, least terns, black skimmers, seabeach amaranth and migrating shorebirds. Two sets of detailed habitat inventories were completed to assess the presence, absence and condition of tidal inlet and sandy beach habitat from Maine to North Carolina in 2012, prior to Hurricane Sandy.
Those reports and associated data products inventoried the abundance and distribution of tidal inlet and sandy beach habitat, as well as anthropogenic (human) modifications to both habitat types. This report and its associated data products assess the storm-induced modifications to tidal inlet and sandy beach habitats caused by Hurricane Sandy, which made landfall in New Jersey on October 29, 2012.
Storm-induced habitat modifications are a result of natural coastal processes during a storm such as a hurricane or nor'easter, as opposed to anthropogenic habitat modifications that are caused by human activities. Storm-induced habitat modifications include the opening of new inlets or temporary storm breaches, the closure of existing inlets, alterations to the width or depth of an inlet, scarping or erosion of dunes, burial or removal of vegetation, changes in the elevation of the beach or adjacent upland area, ephemeral ponding in low-lying areas, hidden changes to the underwater areas adjacent to a beach, and overwash deposits.
Overwash deposits sediment on the landward portion of a beach, within the dune system and adjacent upland areas, and sometimes extends across an island or barrier spit to bury marsh on the bayside shoreline, extending the shoreline farther into the bay or sound. Overwash deposits raise the elevation of the beach and/or upland area, which can reduce the likelihood of future flooding events and make those habitat areas more resilient (less vulnerable) to future flooding events and rising sea level. Overwash deposits or scour of sediments by storm surge floodwaters can expand bare sand or sparsely vegetated habitat areas, refreshing older bare sand or sparsely vegetated areas where vegetation succession was reducing the size of those areas. Ultimately overwash creates new potential nesting areas for several species of birds, including the piping plover. Where overwash extends to the bayside shoreline, new shorebird foraging habitat may be created as well.
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A variety of aerial photography was taken immediately following Hurricane Sandy and is publicly available. These imagery sources include Google Earth (November 1 – 5, 2012), the National Geodetic Service of the National Oceanic and Atmospheric Administration (October 31 – November 6, 2012), the United States Geological Survey (November 4 – 6, 2012), and the Program for the Study of Developed Shorelines at Western Carolina University (October 31 – November 26, 2012). Imagery is available for the shorelines of Connecticut, New York, New Jersey, and portions of Delaware, Maryland, Virginia and North Carolina. The imagery sources were surveyed to identify the location of any new tidal inlets or storm breaches, and the closure of any inlets that were open prior to Hurricane Sandy. A database of tidal inlets opened and closed by Hurricane Sandy was created in Microsoft Excel.
The lengths and locations of sandy beaches following Hurricane Sandy were compared to the lengths and locations of the sandy beaches existing prior to Hurricane Sandy, allowing for the identification of the storm-induced habitat modifications to the length and location of sandy beach habitat. Overwash areas were identified and measured in Google Earth for all areas for which aerial imagery was available. The length of sandy beach modified by overwash was calculated by measuring the length of overwash closest to the beach. This position was roughly in alignment with the dune or vegetation line that existed prior to the storm. Overwash areas may widen inland from the point of measurement, but the spatial area of overwash deposits landward of the beach was not measured and was beyond the scope of this analysis. For the purposes of this study, the focus was the length of sandy beach identified in the pre-Hurricane Sandy beach habitat inventories that was modified by overwash.
Hurricane Sandy Habitat Modifications to Tidal Inlets
Prior to Hurricane Sandy, 399 tidal inlets were open in the U.S. Atlantic Coast breeding range of the piping plover, from Maine to North Carolina. Hurricane Sandy opened at least 33 tidal inlets and storm breaches, 5 of which were pre-existing inlets that periodically open and close that were re-opened by the storm. Four tidal inlets were closed by Hurricane Sandy – two in Connecticut, and one each New York and Virginia.
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