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Topobathymetric Model of Northern California, 1986 to 2019

August 10, 2020

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 Northern 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. This TBDEM consists of the best available multi-source topographic and bathymetric elevation data for the onshore and offshore areas in Northern California. The Northern California TBDEM integrates 26 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 height based on a common geoid (Geoid09) that are normally used for mapping elevation on land based on the North American Vertical Datum of 1988. Every input data source in the TBDEM has been horizontally referenced to UTM Zone 10, NSRS2007. The spatial resolution is 1-meter with the general location ranging from the Golden Gate Bridge to the Oregon border, and extending inland to an elevation of at least +10 m and offshore to the 3-nautical-mile limit of California's State Waters. The overall temporal range of the input topography and bathymetry is 1986 to 2019. The topography surveys are from 2009-2019. The bathymetry is from 1986-2019. The nearshore void zone (not covered by lidar or sonar) was filled by interpolating points from adjacent datasets.