DelmarvaS_SVA_ST.shp - Digital Shoreline Analysis System version 4.1 Transects with Short-Term Rate Calculations for the Delmarva South/Southern Virginia region from Wallops Island, Virginia to the Virginia/North Carolina border

Sandy ocean beaches are a popular recreational destination, often surrounded by communities containing valuable real estate. Development is on the rise despite the fact that coastal infrastructure is subjected to flooding and erosion. As a result, there is an increased demand for accurate information regarding past and present shoreline changes. To meet these national needs, the Coastal and Marine Geology Program of the U.S. Geological Survey (USGS) is compiling existing reliable historical shoreline data along open-ocean sandy shores of the conterminous United States and parts of Alaska and Hawaii under the National Assessment of Shoreline Change project.

There is no widely accepted standard for analyzing shoreline change. Existing shoreline data measurements and rate calculation methods vary from study to study and prevent combining results into state-wide or regional assessments. The impetus behind the National Assessment project was to develop a standardized method of measuring changes in shoreline position that is consistent from coast to coast. The goal was to facilitate the process of periodically and systematically updating the results in an internally consistent manner.

沙质滨海海滩是热门的休闲度假胜地，周边往往环绕着坐拥高价值不动产的社区。尽管沿海基础设施面临洪涝与侵蚀威胁，沿岸开发仍呈上升趋势。由此，社会对精准掌握过去与当前海岸线变化信息的需求日益增长。为满足这一国家层面的需求，美国地质调查局（U.S. Geological Survey, USGS）下属的海岸与海洋地质项目正依托**海岸线变化国家评估（National Assessment of Shoreline Change）**项目，对美国本土48州、阿拉斯加部分区域及夏威夷的开阔洋域沙质海岸沿线的现有可靠历史海岸线数据进行汇编。

目前尚无广泛认可的海岸线变化分析标准。现有海岸线数据测量方法与变化速率计算方法因研究而异，致使各研究结果无法被整合至全州或区域尺度的评估工作中。发起该项目的核心动因，正是开发一套跨海岸保持一致的海岸线位置变化标准化测量方法，其目标是以内部统一的方式，定期且系统地更新评估结果，以简化该更新流程。