Topobathymetric Model for the Southern Coast of California and the Channel Islands, 1930 to 2014

To support the modeling of storm-induced flooding, the USGS Coastal National Elevation Database (CoNED) Applications Project has created an integrated 1-meter topobathymetric digital elevation model (TBDEM) for the Southern California Coast and Channel Islands. The Channel Islands are a chain of eight islands where years of isolation has created unique fauna, flora, and archeological resources. The archipelago extends for 160 miles (257 km) between San Miguel Island in the north and San Clemente Island in the south. Five of the islands are part of Channel Islands National Park (Anacapa, Santa Cruz, Santa Rosa, San Miguel, and Santa Barbara), and the waters surrounding these islands make up the Channel Islands National Marine Sanctuary. High-resolution coastal elevation data is required to identify flood, storm, and sea-level rise inundation hazard zones and other earth science applications, such as the development of sediment transport and storm surge models. The new TBDEM consists of the best available multi-source topographic and bathymetric elevation data for Southern California including the Channel Islands onshore and offshore areas. The Southern California TBDEM integrates 49 different data sources including topographic and bathymetric LiDAR point clouds, Interferometric Synthetic Aperture Radar (IFSAR), hydrographic surveys, single-beam acoustic surveys, and multi-beam acoustic surveys obtained from USGS, NOAA, California State University - Monterey Bay, and Los Angeles County. The topographic and bathymetric surveys were sorted and prioritized based on survey date, accuracy, spatial distribution, and point density to develop a model based on the best available elevation data. Because bathymetric data are typically referenced to tidal datums (such as Mean High Water or Mean Low Water), all tidally-referenced heights were transformed into orthometric heights that are normally used for mapping elevation on land (based on the North American Vertical Datum of 1988). The spatial resolution is 1-meter with the general location ranging from the Mexican Border to Point Conception, and extending offshore to a depth of 2,847 meters. The overall temporal range of the input topography and bathymetry is 1930 to 2014. The topography surveys are from 2005-2014. The bathymetry surveys were acquired between 1930 and 2014. Some of the nearshore void zone (not covered by lidar or multibeam) was filled with NOS surveys from 1967 and 2013.

为支撑风暴诱发洪水的模拟研究，美国地质调查局（USGS）海岸国家高程数据库（Coastal National Elevation Database, CoNED）应用项目为南加州海岸与海峡群岛构建了一体化1米分辨率地形水深数字高程模型（topobathymetric digital elevation model, TBDEM）。海峡群岛由8座岛屿组成，长期的地理隔离孕育了独特的动植物区系与考古资源。该群岛北起圣米格尔岛、南至圣克莱门特岛，绵延160英里（约257千米）。其中5座岛屿隶属于海峡群岛国家公园（阿纳卡帕岛、圣克鲁斯岛、圣罗莎岛、圣米格尔岛与圣巴巴拉岛），群岛周边水域则构成了海峡群岛国家海洋保护区。高精度海岸高程数据是识别洪水、风暴与海平面上升淹没危险区，以及开展沉积物输运、风暴潮模型构建等其他地球科学应用的必要基础。这款全新的TBDEM整合了南加州（含海峡群岛陆上与近岸海域）现有最优的多源地形与水深高程数据。南加州TBDEM共整合了49种不同数据源，包括来自美国地质调查局、美国国家海洋和大气管理局（NOAA）、加州州立大学蒙特雷湾分校与洛杉矶县的地形与水深激光雷达点云、干涉合成孔径雷达（Interferometric Synthetic Aperture Radar, IFSAR）、水文测量数据、单波束声学勘测数据与多波束声学勘测数据。研究团队依据勘测时间、精度、空间分布与点云密度对地形与水深勘测数据进行了排序与优先级划分，基于现有最优高程数据构建了该模型。由于水深数据通常以潮汐基准面（如平均高潮位或平均低潮位）为参考基准，所有潮汐参考高程均被转换为陆地测绘常用的正高（基于1988年北美垂直基准面）。该数据集空间分辨率为1米，覆盖范围北至康塞普申角、南抵美墨边境，并向海延伸至2847米水深区域。输入地形与水深数据的时间跨度为1930年至2014年，其中地形勘测数据采集于2005年至2014年，水深勘测数据则采集于1930年至2014年。部分近岸空白区（未被激光雷达或多波束数据覆盖）通过1967年与2013年的美国国家海洋服务局（National Ocean Service, NOS）勘测数据完成填补。