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Topobathymetric Model for the Central Coast of California, 1929 to 2017

February 8, 2018

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 Central California Coast. High-resolution coastal elevation data is required to identify flood, hurricane, 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 the onshore and offshore areas in Central California. The Central California TBDEM integrates 70 different topographic and bathymetric data sources including LiDAR point clouds, hydrographic surveys, single-beam acoustic surveys, and multi-beam acoustic surveys obtained from USGS, NOAA, and USACE. 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 Point Conception to the Golden Gate Bridge, and extending offshore to a depth of at least 15 meters. The overall temporal range of the input topography and bathymetry is 1929 to 2017. The topography surveys are from 2008-2015. The majority of the bathymetry is from 1996-2011. Some of the nearshore void zone (not covered by lidar or multibeam) was filled with NOS surveys dating back as far as 1929.