Land-cover types, shoreline positions, and sand extents derived From Landsat satellite imagery, Assateague Island to Metompkin Island, Maryland and Virginia, 1984 to 2014

Analysis of multi-decadal wetland changes, and cumulative impact of multiple storms 1984 to 2017

“…Image selection, processing, and classification methods are detailed in Bernier et al (2015) Bernier et al (2015) were excluded from this analysis because visual inspection showed excessive flooding of both wetland and bare earth (beach) environments, indicating high-water conditions at the time of image acquisition. Due to the failure of the scan line corrector on the Landsat 7 satellite in May 2003 (U.S. Geological Survey 2012) and the decommissioning of Landsat 5, there is a 2-year gap between useable images acquired in April 2011 and April 2013, and the effects of Hurricane Irene, the Halloween Nor'Easter, and Hurricane Sandy were assessed collectively.…”

“…Subsequent unsupervised classification of the remaining pixels generated 50 spectral clusters for each image date, which were reduced to seven land-cover classes based on visual interpretation. Qualitative assessment of the data presented in Bernier et al (2015) indicated that the final classed datasets commonly included noise, or ''speckling,'' within open-water bodies that resulted from misclassification of submerged tidal flats or submerged aquatic vegetation as wet marsh. Prior to analysis, we applied a band 5 density slice (e.g., Allen et al 2012;Braud and Feng 1998;Barras et al 2003, Frazier andPage 2000) to further separate land and water areas and remove noise from open-water bodies.…”

“…The final classification (Bernier et al 2015) included water, wet marsh, marsh, forested, mixed vegetation, vegetated bare earth, and bare earth classes. Wet marsh is a sub-category of marsh that is visibly wetter than the surrounding marsh and may include submerged marsh areas and can be differentiated from water by the adsorption of mid-infrared and near-infrared wavelengths and higher spectral reflectance of infrared (Bernier et al 2006).…”

“…Wet marsh is a sub-category of marsh that is visibly wetter than the surrounding marsh and may include submerged marsh areas and can be differentiated from water by the adsorption of mid-infrared and near-infrared wavelengths and higher spectral reflectance of infrared (Bernier et al 2006). Mixed vegetation refers to relatively high reflectance pixels that Bernier et al (2015) interpreted as mixed high marsh and woody scrub/shrub vegetation. Vegetated bare earth includes areas with sparse vegetative coverage or short grasses such as American dune grass (Ammophila breviligulata).…”

“…Although the primary goal of this study was to quantify wetland-change trends, the original classification scheme (Bernier et al 2015) included additional land-cover classes as part of a larger assessment of storm-induced overwash and coastal-vulnerability model sensitivity. The additional classes may also help explain land-cover changes and identify classification errors.…”