TX1970-1975 - Vectorized Shoreline of Texas Derived from 1970-1975 Source Data

There are critical needs for a nationwide compilation of reliable shoreline data. To meet these needs, the USGS has produced a comprehensive database of digital vector shorelines by compiling shoreline positions from pre-existing historical shoreline databases and by generating historical and modern shoreline data. Shorelines are compiled by state and generally correspond to one of four time periods: 1800s, 1920s-1930s, 1970s, and 1998-2002. Each shoreline may represent a compilation of data from one or more sources for one or more dates provided by one or more agencies. Details regarding source are provided in the 'Data Quality Information' section of this metadata report. Shoreline vectors derived from historic sources (first three time periods) represent the high water line at the time of the survey, whereas modern shorelines (final time period) represent the mean high water line.

亟需开展全国范围内可靠海岸线数据集的整合工作。为满足此类需求，美国地质调查局（USGS）通过整合现有历史海岸线数据库中的海岸线位置信息，并生成历史与现代海岸线数据，构建了一套完整的数字矢量海岸线数据库。海岸线按州进行整合，且通常对应以下四个时段之一：19世纪、1920年代-1930年代、1970年代以及1998年-2002年。每条海岸线的数据可整合自一个或多个机构提供的、对应一个或多个观测日期的多源数据。有关数据来源的详细信息，请参见本元数据报告的"数据质量信息"章节。由历史数据源（前三个时段）生成的海岸线矢量代表测绘当时的高水位线，而现代海岸线（最后一个时段）则代表平均高水位线。