Aerial_Shorelines_1940_2015.shp - Dauphin Island, Alabama Shoreline Data Derived from Aerial Imagery from 1940 to 2015

Aerial_WDL_Shorelines.zip features digitized historic shorelines for the Dauphin Island coastline from October 1940 to November 2015. This dataset contains 10 Wet Dry Line (WDL) shorelines separated into 58 shoreline segments alongshore Dauphin Island, AL. The individual sections are divided according to location along the island and shoreline type: open-ocean, back-barrier, marsh shoreline. Imagery of Dauphin Island, Alabama was acquired from several sources including the United States Geological Survey (USGS), the National Agriculture Imagery Program (NAIP), the United States Department of Agriculture's Farm Service Agency (USDA, FSA), and the University of Alabama. These images were downloaded directly from the source's website or received as a hard copy via mail. Using ArcMap 10.3.1, the imagery was used to delineate and digitize historical shorelines at the wet-dry line along sandy beaches and the mean high water line where vegetation indicated. These shorelines were digitized for use in long-term shoreline and wetland analyses and physical change assessments. Shorelines for all 10 dates were compiled into a database for use with the Digital Shoreline Analysis System (DSAS; Thieler and others, 2009) to quantify rates of shoreline change over the 1940-2015 time period. The migration of shorelines through time is presented as the linear regression rate (LRR) in the associated back-barrier and open ocean transect files, which are also included in the USGS data release (https://coastal.er.usgs.gov/data-release/provisional/ip086178/).数据集Aerial_WDL_Shorelines.zip 包含1940年10月至2015年11月期间多芬岛（Dauphin Island）海岸线的数字化历史岸线数据。本数据集共包含10条干湿线（Wet Dry Line, WDL）岸线，沿阿拉巴马州多芬岛沿岸分为58个岸线片段。 这些岸线片段根据岛屿沿岸位置及岸线类型划分为三类：开阔洋面岸段、障壁后缘岸段与潮沼岸线。 本次使用的阿拉巴马州多芬岛影像数据来源于多个渠道，包括美国地质调查局（United States Geological Survey, USGS）、国家农业影像计划（National Agriculture Imagery Program, NAIP）、美国农业部农场服务局（United States Department of Agriculture's Farm Service Agency, USDA, FSA）以及阿拉巴马大学。 这些影像要么直接从数据源网站下载获取，要么通过邮寄获得纸质副本。 研究使用ArcMap 10.3.1软件，对影像进行解译与数字化，以绘制沙滩沿线的干湿线以及存在植被标识区域的平均高潮线位置的历史岸线。 本次数字化岸线旨在用于长期岸线与湿地分析以及物理变化评估。 研究将10个观测时期的岸线整合至数据库中，配合数字岸线分析系统（Digital Shoreline Analysis System, DSAS; Thieler等，2009）对1940-2015年期间的岸线变化速率进行量化分析。 随时间推移的岸线迁移情况以线性回归速率（linear regression rate, LRR）的形式呈现在相关的障壁后缘与开阔洋面断面文件中，这些文件也包含在本次美国地质调查局发布的数据集中（https://coastal.er.usgs.gov/data-release/provisional/ip086178/）。