MauiN_baseline - Offshore baseline used to cast shore-perpendicular transects for measurement of historical shoreline positions along the North Coast of Maui, Hawaii (Waihee to Kuau)

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.

沙质海滨是广受青睐的休闲度假目的地，周边往往分布着坐拥高价值不动产的聚居社区。尽管沿海基础设施持续面临洪涝与侵蚀威胁，沿岸开发仍呈上升态势。在此背景下，社会对精准掌握历史及当前海岸线变化相关信息的需求日益高涨。为满足这一国家层面的应用需求，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“海岸线变化国家评估”项目，正系统性收集美国本土、阿拉斯加部分区域及夏威夷的开放洋域沙质岸线沿线现存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。现有海岸线数据测量手段与变化速率计算方法因研究而异，导致相关成果无法整合为州级或区域级的综合评估。本次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海岸线位置变化测量方法，目标是实现以内部一致的方式，定期、系统地更新评估结果。