Quantifying Changes along Mainland Marshes in the Virginia Coast Reserve, 1957-2011: Tabular data

This dataset contains data that quantifies the long-term rate of change in the shoreline position along seaside mainland marshes of the Virginia Coast Reserve between 1957 and 2009. It also contains data that delineates potential areas available for future marsh transgression under three different sea level rise scenarios based on current land use and elevation data. Additionally, the tabular data contains sediment grain size analysis results from sediment cores collected in 2011 at six of the ten study sites, plus GPS elevation profiles of the marsh edges at those sites. Shoreline position was determined for ten individual mainland marsh sites 3-4 km in length, plus the full length of the mainland marsh edge along the entire seaside length of the peninsula, based on aerial imagery from 1957, 1966, 1989, 2002, and 2009. The ten marsh sites (north to south) were at Gargathy Bay, Cedar Island Bay, Hummock Cove, Wachapreague, North Matulakin Marsh, Short and Long Prong Marshes, Crabbing Marsh, Oyster, Mockhorn Bay, and Marion Scott Cove. Metrics of the rate of change were determined using the Digital Shoreline Analysis System (DSAS), an ArcGIS extension (Thieler et al., 2009). Given the digitized shorelines and a parallel baseline as inputs, DSAS creates evenly-spaced transects perpendicular to the baseline and calculates the rate of shoreline change using a variety of methods, including the End Point Rate (EPR), linear regression rate (LRR), and various iterative and weighted linear regressions. Statistics for these regressions are included in the transect and summary point attribute data. Areas potentially suitable for future marsh transgression based on land use were determined based on 2005 NOAA Coastal Change Analysis Program (CCAP) data and consisted of upland and wetland areas currently in forest or scrub/shrub cover and adjacent to existing marshes. The acreage of these potential marsh areas that could be inundated and unavailable for marsh transgression under three different sea level rise scenarios was also determined based on elevation data from 2010 LiDAR surveys (see VCRLTER dataset VCR12194). Data on sediment grain size characteristics of sediment cores collected at six of the ten field sites is included with the tabular data. Sediment samples were collected using a 2.5 cm diameter core to a depth of 5 cm. Ten samples were collected at each marsh at approximately 50 m intervals. Grain size analysis was performed using a Beckman Coulter Particle Size Analyzer (PSA). The average sediment grain size distribution was then determined for each site. Also at six of the ten sites, elevation profiles were measured along and perpendicular to the marsh edge using GPS.