Digital Shoreline Analysis System version 4.1 Transects with Short-Term Rate Calculations for the Greater Boston region from the southern side of Cape Ann, Massachusetts to Sandy Neck Beach in Sandwich, Massachusetts (GreaterBoston_ST.shp)

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.

滨海沙质海滩是热门的休闲度假胜地，周边多分布着坐拥高价值不动产的人居社区。尽管沿海基础设施面临洪涝与侵蚀威胁，沿岸开发热度仍持续攀升。因此，精准掌握岸线历史与现状变化情况的需求愈发迫切。为满足这些国家级需求，美国地质调查局（U.S. Geological Survey, USGS）下属的海岸与海洋地质项目组，依托《岸线变化国家评估》项目，正在汇编美国本土48州沿海开放沙岸、阿拉斯加部分区域及夏威夷群岛的现有可靠历史岸线数据。
当前岸线变化分析领域尚无广泛认可的统一标准。现有岸线数据的测量手段与岸线变化速率的计算方法因研究而异，导致不同研究的结果无法整合为州级或区域级的评估成果。本项目的立项初衷，便是研发一套可在全美海岸通用的标准化岸线位置变化测量方法。项目旨在构建一套内部统一的标准化流程，以实现岸线变化评估结果的定期系统性更新。