Offshore baseline for New England South coastal region from Dartmouth, Massachusetts to Napatree Point, Rhode Island, generated to calculate shoreline change rates (NE_South_baseline.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.沙质滨海沙滩是热门休闲度假胜地，周边往往坐落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的双重威胁，海岸开发热度仍持续攀升。因此，社会对精准掌握历史与当前海岸线变化情况的需求与日俱增。为满足此类国家层面的需求，美国地质调查局（U.S. Geological Survey, USGS）下属的海岸与海洋地质项目组，正依托《海岸线变化国家评估》（National Assessment of Shoreline Change）项目，收集美国本土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已有的可靠历史海岸线数据。当前尚无被广泛认可的海岸线变化分析标准。不同研究采用的海岸线数据测量方式与侵蚀速率计算方法各不相同，导致各研究结果无法整合为州级或区域级的综合评估成果。本《海岸线变化国家评估》项目的核心动因，在于研发一套适用于全海岸区域、标准统一的海岸线位置变化测量方法，其目标在于简化以内部统一规范，定期且系统地更新评估结果的工作流程。