Shorelines of the Long Island coastal region used in shoreline change analysis for the Long Island region from Montauk Point to the entrance of Raritan Bay, New York (LongIsland_shorelines.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.

沙质滨海海滩是热门休闲度假胜地，周边往往分布着拥有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，滨海开发热度仍持续攀升。因此，精准获取过往及当前海岸线变化相关信息的需求与日俱增。为满足这一国家层面的需求，美国地质调查局（U.S. Geological Survey, USGS）海岸与海洋地质项目组正依托《海岸线变化国家评估》项目，对美国本土、阿拉斯加部分区域及夏威夷的开放洋域沙质海岸沿线现有可靠历史海岸线数据进行整合汇编。
当前尚无被广泛认可的海岸线变化分析标准。现有海岸线数据测量方式与岸线变化速率计算方法因研究项目不同而存在差异，导致相关成果无法整合至州级或区域级评估工作中。本《海岸线变化国家评估》项目的发起初衷，便是开发一套跨所有海岸统一的标准化海岸线位置变化测量方法。其目标在于实现以内部一致的方式，定期且系统地更新相关评估成果的流程。