GreaterBoston_ST.shp - 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

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，周边往往坐落着拥有高价值不动产的居民区。尽管沿海基础设施面临洪涝与侵蚀威胁，滨海开发仍呈增长态势。因此，社会对精准掌握过去与当前海岸线变化情况的需求日益增长。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，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现存的可靠历史海岸线数据进行汇编。

目前尚无被广泛认可的海岸线变化分析标准。现有海岸线数据的测量方式与变化速率计算方法因研究而异，导致无法将各研究结果整合至州级或区域级评估中。启动海岸线变化国家评估项目的初衷，便是研发一套跨海岸统一的标准化海岸线位置变化测量方法。该项目的目标是实现以内部一致的方式，定期且系统地更新评估结果，以此简化相关流程。