Salt Marsh Boundaries and Areas of Change on the Eastern Shore of Virginia, USA

Between 2002-2017, migration and edge erosion were measured in three mainland geomorphic marsh types (headland, valley, hammock) and were used to assess the rate and spatial extent of marsh change for the Eastern Shore of Virginia. The boundary between high salt marsh and forest was delineated by hand digitizing 2002 and 2017 imagery and the area was determined between the 2002 and 2017 treelines at each of the salt marshes. The 2017 delineated treelines and marsh edges were confirmed through personal observations by walking the along both types of boundaries, comparing them to printouts of the delineated boundaries. There were few discrepancies, but where differences were observed, the delineated boundaries were adjusted to account for field observations. All ESVA seaside marshes were identified using aerial imagery and GIS. The marsh counts shapefile is the result of that analysis. Each point identifies an individual marsh.

2002年至2017年间，研究团队针对三种大陆地貌湿地类型（岬角型、河谷型、岛丘型，headland, valley, hammock）开展了迁移与边缘侵蚀观测，以此评估弗吉尼亚东海岸（Eastern Shore of Virginia，以下简称ESVA）湿地变化的速率与空间范围。研究人员通过手动数字化2002年与2017年的遥感影像，划定了高盐沼与森林的边界，并计算了各盐沼区域2002年与2017年林线之间的面积。2017年划定的林线与湿地边界，通过沿两类边界开展徒步实地观测进行验证：将勾绘边界的打印件与实地场景进行比对。尽管仅存在少量偏差，但在发现差异的区域，研究人员会依据实地观测结果对勾绘边界进行修正。所有弗吉尼亚东海岸滨海湿地（ESVA）均通过航空影像与地理信息系统（GIS，Geographic Information System）完成识别。本次分析的成果即为湿地计数形状文件（shapefile），其中每个点位均对应一处独立湿地。