OahuN_shorelines - Shorelines of the northern coastal region of Oahu, Hawaii, from Camp Erdman to Kahuku, 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.沙质滨海海滩是热门的休闲度假目的地，周边往往坐落着坐拥高价值不动产的社区。尽管沿海基础设施易遭受洪涝与侵蚀破坏，海岸开发活动仍呈上升态势。因此，社会对准确获取海岸带过去与当前变迁相关信息的需求日益攀升。为满足这类国家层面的需求，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，依托海岸变迁国家评估（National Assessment of Shoreline Change）项目，正在汇编美国本土48州、阿拉斯加部分区域以及夏威夷的开放海域沙质海岸沿线现有的可靠历史岸线数据。由历史与现代数据源提取的岸线矢量数据，表征的是低潮位线（滩脚）。当前尚未形成被广泛认可的海岸变迁分析标准。现有岸线数据的测量方法与岸线变迁速率计算方法因研究项目各不相同，导致无法将各研究结果整合为州级或区域级的统一评估成果。本次海岸变迁国家评估项目的立项初衷，便是开发一套跨海岸统一的标准化岸线位置变迁测量方法。其目标是实现以内部统一标准定期、系统更新评估结果的流程规范化。