San Francisco Bay-Delta bathymetric/topographic digital elevation model(DEM)
a high resolution 10 meter per pixel digital elevation model dem was created for the sacramento san joaquin delta using both bathymetry and topography data this dem is the result of collaborative efforts of the u s geological survey usgs and the california department of water resources dwr the base of the dem is from a 10 m dem released in 2004 and updated in 2005 foxgrover and others 2005 that used environmental systems research institute esri arcgis topo to raster module to interpolate grids from single beam bathymetric surveys collected by dwr the army corp of engineers coe the national oceanic and atmospheric administration noaa and the usgs into a continuous surface the topo to raster interpolation method was specifically designed to create hydrologically correct dems from point line and polygon data environmental systems research institute inc 2015 elevation contour lines were digitized based on the single beam point data for control of channel morphology during the interpolation process checks were performed to ensure that the interpolated surfaces honored the source bathymetry and additional contours and or point data were added as needed to help constrain the data the original data were collected in the tidal datum mean lower or low water mllw or the national geodetic vertical datum of 1929 ngvd29 all data were converted to ngvd29 the 2005 usgs dem was updated by dwr first by converting the dem to the current modern datum of national geodetic vertical datum of 1988 ngvd88 and then by following the methodology of the usgs dem established for the 2005 dem foxgrover and others 2005 for adding newly collected single and multibeam bathymetric data they then included topographic data from lidar surveys providing the first dem that included the land water interface wang and ateljevich 2012 the usgs further updated and expanded the dwr dem with the inclusion of usgs interpolated sections of single beam bathymetry data collected by the coe and usgs scientists expanding the dem to include the northernmost areas of the sacramento san joaquin delta and by making use of a two meter seamless bathymetric topographic dem from the usgs eros data center 2013 of the san francisco bay region the resulting 10 meter usgs dem encompasses the entirety of suisun bay beginning with the carquinez strait in the west east to california interstate 5 north following the path of the yolo bypass and the sacramento river up to knights landing and the american river northeast to the nimbus dam and south to areas around tracy the dem incorporates the newest available bathymetry data at the time of release as well as including at minimum a 100 meter band of available topography data adjacent to most shorelines no data areas within the dem are areas where no elevation data exists either due to a gap in the land water interface or because lidar was collected over standing water that was then cut out of the dem