MauiK_shorelines - Shorelines of the Kihei coastal region of Maui, Hawaii, from Maalaea to Makena, used in shoreline change analysis.

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. Shoreline vectors derived from historic and modern sources represent the low water mark (beach toe).

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目的地，周边往往分布着坐拥珍贵不动产的居民区。尽管沿海基础设施面临洪涝与侵蚀威胁，滨海开发仍呈持续增长态势。因此，社会对精准掌握海岸过去与当前变迁状况的需求日益攀升。为满足此类国家层面的需求，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《海岸变迁国家评估》项目，对美国本土48州、阿拉斯加部分区域及夏威夷的外海沙质海岸的现有可靠历史岸线数据进行整编。从历史与现代数据源提取的岸线矢量数据，对应低潮位线（海滩坡脚）。
目前尚无被广泛认可的海岸变迁分析标准。现有岸线数据测量方法与岸线变迁速率计算方法因研究而异，导致无法将不同研究的结果整合为全州或区域尺度的评估成果。发起《海岸变迁国家评估》项目的核心动因，便是研发一套跨海岸统一的标准化岸线位置变化测量方法。该项目的目标在于，实现以内部统一标准定期、系统地更新评估成果的流程化操作。