This service hosts a raster image generated from raw DEM (Digital Elevation Model) data gathered for the Shuttle Radar Topography Mission (SRTM). The mission was co-sponsored by the National Aeronautics and Space Administration (NASA) and National Geospatial-Intelligence Agency (NGA). NASA's Jet Propulsion Laboratory (JPL) performed preliminary processing of SRTM data and forwarded it to the NGA for further processing and distribution. The raster image hosted by this service was generated using ArcGIS tools to convert DEM data for the state of California into a raster image. The results were reprojected into World Mercator (WKID: 54004) for display purposes. Pixel size is approximately 90 meters and vertical units are defined in meters. ESRI reserves the right to change or remove this service at any time and without notice. Copyright: Copyright:© 2010 ESRI

NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated bathymetric-topographic DEMs are used to support tsunami forecasting and warning efforts at the NOAA Center for Tsunami Research, Pacific Marine Environmental Laboratory (PMEL). The DEMs are part of the tsunami forecast system SIFT (Short-term Inundation Forecasting for Tsunamis) currently being developed by PMEL for the NOAA Tsunami Warning Centers, and are used in the MOST (Method of Splitting Tsunami) model developed by PMEL to simulate tsunami generation, propagation, and inundation. Bathymetric, topographic, and shoreline data used in DEM compilation are obtained from various sources, including NGDC, the U.S. National Ocean Service (NOS), the U.S. Geological Survey (USGS), the U.S. Army Corps of Engineers (USACE), the Federal Emergency Management Agency (FEMA), and other federal, state, and local government agencies, academic institutions, and private companies. DEMs are referenced to the vertical tidal datum of North American Vertical Datum of 1988 (NAVD 88) or Mean High Water (MHW) and horizontal datum of World Geodetic System 1984 (WGS84). Cell size for the DEMs ranges from 1/3 arc-second (~10 meters) to 3 arc-seconds (~90 meters).

Citation and Main Description:

This product is described in Chapter 5 of the 2018 DWR Delta Modeling Section annual report, produced jointly with USGS.

https://data.cnra.ca.gov/dataset/methodology-for-flow-and-salinity-estimates-in-the-sacramento-san-joaquin-delta-and-suisun-marsh/resource/84d4fd29-c839-4efa-82be-b58f7ed176db

Domain and Product

This product is a mutually compatible suite of DEMs covering most of the aquatic and terrestrial areas of the Bay-Delta. The product was derived from original point data collections, lidar and other DEMs. Also included in the resources are images and shapefiles describing the source data.

Changes between 4.1 and 4.2 are documented in the change log below. Changes prior to that are recorded in the 4.1 web page.

Changes in version 4 relative to prior products are limited to the region east of the Carquinez Strait (starting around Carquinez Bridge). To facilitate compatibility between products released by DWR and USGS/NOAA partners, DWR distributes the region west of the active work at 10m resolution but does not actively work in this region. The San Pablo Bay boundary of active revision in the present product in a place where its source data matches that of other Bay elevation models, e.g., the 2m seamless high-resolution bathymetric and topographic DEM of San Francisco Bay by USGS Earth Resources Observation and Science Center (EROS) (https://topotools.cr.usgs.gov/coned/sanfrancisco.php ), the 2010 San Francisco Bay DEM by National Oceanic and Atmospheric Administration (https://www.ngdc.noaa.gov/metaview/page?xml=NOAA/NESDIS/NGDC/MGG/DEM/iso/xml/741.xml&view=getDataView&header=none ) or the prior (version 3) 10m digital elevation model (https://data.cnra.ca.gov/dataset/san-francisco-bay-and-sacramento-san-joaquin-delta-dem-v3 ).The 10m DEM for the Bay-Delta is based on the first on the list, i.e. EROS’ 2m DEM for the Bay

Version: 4.2

• Time Completed: December 2020
• Horizontal Datum: NAD83
• Spheroid:GRS1980
• Projection:UTM_Zone_10N (meters)
• Vertical Datum:NAVD88 (meters)

Changes since 4.1

• Incorporate 1m DEMs from Cache Slough Complex (USGS, 2020) into 2m DEMs for Yolo and North Delta.
• Develop 1m DEM for Lindsey Slough Restoration area based on Handley DEM (UCD, 2015) and Lindsey Slough, Cache Sough, Liberty Island DEM (USGS, 2020) and and merge it into 2m Yolo DEM.
• Develop 2m DEM for Tom Paine Slough based on 2018 Bathymetry Survey (DWR, NCRO) and 2017 LiDAR (DWR) and merge it with 2m DEM for South Delta.
• Develop 2m DEM for Suisun Slough based on 2018 Bathymetry Survey (DWR, NCRO) and 2017 LiDAR (DWR) and merge it with 2m DEM for Montezuma Slough.
• Develop 2m DEM for Georgiana Slough based on 2019 Bathymetry Survey (DWR, NCRO) and 2017 LiDAR (DWR) and merge it with 2m DEM for North Delta.
• Develop 2m DEM for Sacramento River between its junctions with American River and Sutter Slough based on 2019 Bathymetry Survey (DWR, NCRO) and 2017 LiDAR (DWR) and merge it with 2m DEM for North Delta.
• Incorporate all the 2m additions and modifications done for Yolo, North Delta, Montezuma Slough and South Delta into the 10m DEM for Delta and Bay-Delta.

NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated bathymetric-topographic DEMs are used to support tsunami forecasting and modeling efforts at the NOAA Center for Tsunami Research, Pacific Marine Environmental Laboratory (PMEL). The DEMs are part of the tsunami forecast system SIFT (Short-term Inundation Forecasting for Tsunamis) currently being developed by PMEL for the NOAA Tsunami Warning Centers, and are used in the MOST (Method of Splitting Tsunami) model developed by PMEL to simulate tsunami generation, propagation, and inundation. Bathymetric, topographic, and shoreline data used in DEM compilation are obtained from various sources, including NGDC, the U.S. National Ocean Service (NOS), the U.S. Geological Survey (USGS), the Canadian Hydrographic Service (CHS), the Puget Sound Lidar Consortium (PSLC), the Joint Airborne Lidar Bathymetry Technical Center of Expertise (JALBTCX), Canadian Digital Elevation Data (CDED) and other international, federal, state, and local government agencies, academic institutions, and private companies. DEMs are referenced to the vertical tidal datums of Mean High Water (MHW) and North American Vertical Datum of 1988 (NAVD 88) and horizontal datum of World Geodetic System 1984 (WGS 84). Grid spacings for the DEMs range from 1/3 arc-second (~10 meters) to 3 arc-seconds (~30 meters).

This digital elevation model (DEM) is a part of a series of DEMs produced for the National Oceanic and Atmospheric Administration Office for Coastal Management's Sea Level Rise and Coastal Flooding Impacts Viewer. The DEMs created for this project were developed using the NOAA National Weather Service's Weather Forecast Office (WFO) boundaries. Because the WFO boundaries can cover large areas, the WFO DEM was divided into smaller DEMs to ensure more manageable file sizes. The San Francisco Bay/Monterey (CA) WFO DEM was split into three smaller DEMs. They are divided along county lines and are: 1. San Francisco Bay/Monterey (CA) WFO - Santa Cruz and Monterey Counties 2. San Francisco Bay/Monterey (CA) WFO - Contra Costa, San Francisco, Alameda, San Mateo, and Santa Clara Counties 3. San Francisco Bay/Monterey (CA) WFO - Sonoma, Marin, Napa, and Solano Counties This metadata record describes the DEM for the San Francisco Bay/Monterey (CA) WFO - Sonoma, Marin, Napa, and Solano Counties. The DEM includes the best available lidar data known to exist at the time of DEM creation for the coastal areas of Sonoma, Marin, Napa, and Solano Counties, that met project specifications. The DEM is derived from LiDAR data collected for the California Coastal Conservancy, NOAA and the United States Geological Survey between 2009 and 2011. Hydrographic breaklines used in the creation of the DEM were obtained from the California Coastal Conservancy, NOAA or the USGS. The DEMs are hydro flattened such that water elevations are less than or equal to 0 meters. The DEM is referenced vertically to the North American Vertical Datum of 1988 (NAVD88) with vertical units of meters and horizontally to the North American Datum of 1983 (NAD83). The resolution of the DEM is approximately 5 meters.

NOAA's National Centers for Environmental Information (NCEI) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated bathymetric-topographic DEMs are used to support individual coastal States as part of the National Tsunami Hazard Mitigation Program's (NTHMP) efforts to improve community preparedness and hazard mitigation. Bathymetric, topographic, and shoreline data used in DEM compilation are obtained from various sources including: NOAA; the U.S. Geological Survey (USGS); and other federal, state, and local government agencies, academic institutions, and private companies. DEMs are referenced to the vertical datum of NAVD 88 and horizontal datum of World Geodetic System 1984 geographic (WGS 84). Grid spacing for the DEM is 1/3 arc-second (~10 meters).

The High Resolution Digital Elevation Model (HRDEM) product is derived from airborne LiDAR data (mainly in the south) and satellite images in the north. The complete coverage of the Canadian territory is gradually being established. It includes a Digital Terrain Model (DTM), a Digital Surface Model (DSM) and other derived data. For DTM datasets, derived data available are slope, aspect, shaded relief, color relief and color shaded relief maps and for DSM datasets, derived data available are shaded relief, color relief and color shaded relief maps. The productive forest line is used to separate the northern and the southern parts of the country. This line is approximate and may change based on requirements. In the southern part of the country (south of the productive forest line), DTM and DSM datasets are generated from airborne LiDAR data. They are offered at a 1 m or 2 m resolution and projected to the UTM NAD83 (CSRS) coordinate system and the corresponding zones. The datasets at a 1 m resolution cover an area of 10 km x 10 km while datasets at a 2 m resolution cover an area of 20 km by 20 km. In the northern part of the country (north of the productive forest line), due to the low density of vegetation and infrastructure, only DSM datasets are generally generated. Most of these datasets have optical digital images as their source data. They are generated at a 2 m resolution using the Polar Stereographic North coordinate system referenced to WGS84 horizontal datum or UTM NAD83 (CSRS) coordinate system. Each dataset covers an area of 50 km by 50 km. For some locations in the north, DSM and DTM datasets can also be generated from airborne LiDAR data. In this case, these products will be generated with the same specifications as those generated from airborne LiDAR in the southern part of the country. The HRDEM product is referenced to the Canadian Geodetic Vertical Datum of 2013 (CGVD2013), which is now the reference standard for heights across Canada. Source data for HRDEM datasets is acquired through multiple projects with different partners. Since data is being acquired by project, there is no integration or edgematching done between projects. The tiles are aligned within each project. The product High Resolution Digital Elevation Model (HRDEM) is part of the CanElevation Series created in support to the National Elevation Data Strategy implemented by NRCan. Collaboration is a key factor to the success of the National Elevation Data Strategy. Refer to the “Supporting Document” section to access the list of the different partners including links to their respective data.

A seamless, three-meter digital elevation model (DEM) was constructed for the entire Southern California coastal zone, extending 473 km from Point Conception to the Mexican border. The goal was to integrate the most recent, high-resolution datasets available (for example, Light Detection and Ranging (Lidar) topography, multibeam and single beam sonar bathymetry, and Interferometric Synthetic Aperture Radar (IfSAR) topography) into a continuous surface from at least the 20-m isobath to the +20-m elevation contour.

This project merged recently collected topographic, bathymetric, and acoustic elevation data along the entire California coastline from approximately the 10 meter elevation contour out to California's 3 mile state water's boundary. This metadata record describes the Digital Elevation Model (DEM) created from the lidar and multibeam data. The DEM has a 1m cell size. Topographic LiDAR: The topographic lidar data used in this merged project was the 2009-2011 CA Coastal Conservancy Lidar Project. The data were collected between October 2009 and August 2011. This collection was a joint effort by the NOAA Office for Coastal Management (OCM); the California State Coastal Conservancy (SCC) Ocean Protection Council (OPC); Scripps Institution of Oceanography; and the Joint Airborne Lidar Bathymetry Technical Center of Expertise (JALBTCX). The data coverage extends landward 500 m from the shoreline, along the entire California coastline. The LAS classifications are as follows: 1-Unclassified, 2-Ground, 7-Noise, 9-Water, 10- Mudflats, 12-Overlap. The LAS points were manually re-classified from water and unclassified to ground in offshore areas where necessary. Bathymetric LiDAR: The bathymetric lidar data used in this merged project was 2009-2010 U.S. Army Corps of Engineers (USACE) Joint Airborne Lidar Bathymetry Center of Expertise (JALBTCX) lidar, provided by JALBTCX. The data were collected for the California Coastal Mapping Project (CCMP). The original data were in ASCII format and were converted to LAS v1.2. The LAS data were classified as follows: 21-Non-submerged Bathymetry, 22-Bathymetry, 23-Ignored Submerged Bathymetry/Overlap. Multibeam Acoustic Data: The acoustic data data used in this merged project were provided by the California Seafloor Mapping Program (CSMP) Ocean Protection Council and NOAA's National Geophysical Data Center (NGDC). The original data were in ASCII format and were converted to LAS v1.2. NOAA's VDatum software was used to vertically transform soundings from mean lower low water (MLLW) tidal datum to NAVD88 orthometric datum where necessary. The LAS data were classified as follows: 25-Submerged Acoustic, 26-Ignored Submerged Acoustic/Overlap. Upon receipt of the data, the NOAA Office for Coastal Management (OCM) converted some of the classifications for data storage and Digital Coast provisioning purposes. The following are the classifications of data available from the NOAA Digital Coast: 1 - Unclassified, 2 - Ground, 7 - Low point (noise), 9 - Water, 11 - Bathymetry, 12 - Overlap, 13 - Submerged Acoustic, 14 - Non-Submerged Bathymetry, 15 - Ignored Submerged Bathymetry/Overlap, 16 - Ignored Submerged Acoustic/Overlap

This metadata describes a digital elevation model (DEM) created from bathymetric and topographic data collected between 2004 and 2019 in the Cache Slough Complex (CSC), northern Sacramento-San Joaquin Delta, California. We merged the newly collected bathymetric and topographic data presented in this data release (DOI:10.5066/P9AQSRVH) with 2019 surveys by the California Department of Water Resources (DWR), 2017 USGS Sacramento Delta Lidar, and 2004 bathymetry data from the Army Corp of Engineers. Small gaps of missing data were filled with existing DWR/USGS Delta DEMs to produce a seamless DEM of the Cache Slough Complex with a grid resolution of 1 m. Remaining gaps in the DEM are areas where there is currently no available data.

These data were created as part of the National Oceanic and Atmospheric Administration Office for Coastal Management's efforts to create an online mapping viewer called the Sea Level Rise and Coastal Flooding Impacts Viewer. It depicts potential sea level rise and its associated impacts on the nation's coastal areas. The purpose of the mapping viewer is to provide coastal managers and scientists with a preliminary look at sea level rise and coastal flooding impacts. The viewer is a screening-level tool that uses nationally consistent data sets and analyses. Data and maps provided can be used at several scales to help gauge trends and prioritize actions for different scenarios. The Sea Level Rise and Coastal Flooding Impacts Viewer may be accessed at: https://coast.noaa.gov/slr. This metadata record describes the Catalina California digital elevation model (DEM), which is a part of a series of DEMs produced for the National Oceanic and Atmospheric Administration Office for Coastal Management's Sea Level Rise and Coastal Flooding Impacts Viewer described above. This DEM includes the best available lidar known to exist at the time of DEM creation that met project specifications. This DEM includes data for Catalina Island, California. The DEM was produced from the following lidar data sets: 1. 2015 - 2016 LARIAC Lidar: Los Angeles Region, CA The DEM is referenced vertically to the North American Vertical Datum of 1988 (NAVD88) with vertical units of meters and horizontally to the North American Datum of 1983 (NAD83). The resolution of the DEM is approximately 3 meters.

NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated bathymetric-topographic DEMs are used to support tsunami forecasting and warning efforts at the NOAA Center for Tsunami Research, Pacific Marine Environmental Laboratory (PMEL). The DEMs are part of the tsunami forecast system SIFT (Short-term Inundation Forecasting for Tsunamis) currently being developed by PMEL for the NOAA Tsunami Warning Centers, and are used in the MOST (Method of Splitting Tsunami) model developed by PMEL to simulate tsunami generation, propagation, and inundation. Bathymetric, topographic, and shoreline data used in DEM compilation are obtained from various sources, including NGDC, the U.S. National Ocean Service (NOS), the U.S. Geological Survey (USGS), the U.S. Army Corps of Engineers (USACE), the Federal Emergency Management Agency (FEMA), and other federal, state, and local government agencies, academic institutions, and private companies. DEMs are referenced to the vertical tidal datum of Mean High Water (MHW) and horizontal datum of World Geodetic System 1984 (WGS84). Grid spacings for the DEMs range from 1/3 arc-second (~10 meters) to 3 arc-seconds (~90 meters).

This product is superseded by version 4.2. See: https://data.cnra.ca.gov/dataset/san-francisco-bay-and-sacramento-san-joaquin-delta-dem-for-modeling-version-4-2

Citation and Main Description:

This product is described in Chapter 5 of the 2018 DWR Delta Modeling Section annual report, produced jointly with USGS.

https://water.ca.gov/-/media/DWR-Website/Web-Pages/Library/Modeling-And-Analysis/Files/Modeling-and-Analysis-PDFs/FINAL6BayDelta39thProgress-Report071918.pdf

Domain and Product

Changes between 4.0 and 4.1 are documented in the change log below and are most pronounced in the Suisun Marsh region and in the incorporation of some improvements in the South Delta.

Changes in version 4 relative to prior products are limited to the region east of the Carquinez Strait (starting around Carquinez Bridge). To facilitate compatibility between products released by DWR and USGS/NOAA partners, DWR distributes the region west of the active work at 10m resolution but does not actively work in this region. The San Pablo Bay boundary of active revision in the present product in a place where its source data matches that of other Bay elevation models, e.g., the 2m seamless high-resolution bathymetric and topographic DEM of San Francisco Bay by USGS Earth Resources Observation and Science Center (EROS) (https://topotools.cr.usgs.gov/coned/sanfrancisco.php ), the 2010 San Francisco Bay DEM by National Oceanic and Atmospheric Administration (https://www.ngdc.noaa.gov/metaview/page?xml=NOAA/NESDIS/NGDC/MGG/DEM/iso/xml/741.xml&view=getDataView&header=none ) or the prior (version 3) 10m digital elevation model (https://data.cnra.ca.gov/dataset/san-francisco-bay-and-sacramento-san-joaquin-delta-dem-v3 ).The 10m DEM for the Bay-Delta is based on the first on the list, i.e. EROS’ 2m DEM for the Bay

New work reported here was done at 2m resolution, although the improvements have been incorporated into the 10m products as much as possible. Relative to the previous DWR release (https://data.cnra.ca.gov/dataset/san-francisco-bay-and-sacramento-san-joaquin-delta-dem-v3), the 2m DEM product reported here consolidates work at this resolution into a small number of larger surfaces representing approximately one-third of the Delta (link to the Coverage Areas page). Laterally, the 2m models now extend over the levee crest as needed to match well with Delta LiDAR (http://www.atlas.ca.gov/download.html#/casil/imageryBaseMapsLandCover/lidar2009 ), the main terrestrial source of data used in this work. The 10m product (link to the Coverage Areas page) is based on the updated USGS DEM (https://www.sciencebase.gov/catalog/item/58599681e4b01224f329b484 ). In places where updated 2m models overlap the 10 meters, the 10m base elevation model was updated by resampling the new 2m model and adding levee enforcement. At the border between the 2m and 10m models, the two resolutions were locally edge-matched over a small region to maintain smoothness. For more information, please refer to the report: A Revised Continuous Surface Elevation Model for Modeling (link to Chapter 5 in the 2018 Delta Modeling Section Annual Report (https://water.ca.gov/-/media/DWR-Website/Web-Pages/Library/Modeling-And-Analysis/Files/Modeling-and-Analysis-PDFs/FINAL6BayDelta39thProgress-Report071918.pdf). Please note that by agreement with our data providers we distribute only our own integrated maps, not the original source point data. (https://water.ca.gov/-/media/DWR-Website/Web-Pages/Library/Modeling-And-Analysis/Files/Modeling-and-Analysis-PDFs/FINAL6BayDelta39thProgress-Report071918.pdf

Version: 4.1

• Time Completed: December 2018
• Horizontal Datum: NAD83
• Spheroid:GRS1980
• Projection:UTM_Zone_10N (meters)
• Vertical Datum:NAVD88 (meters)

Data Sources

https://data.cnra.ca.gov/dataset/san-francisco-bay-and-sacramento-san-joaquin-delta-dem-for-modeling-version-4/resource/981a57b5-e16f-4632-b7e0-4a533534a79c

Coverage Areas

https://data.cnra.ca.gov/dataset/san-francisco-bay-and-sacramento-san-joaquin-delta-dem-for-modeling-version-4/resource/2e3f2b6e-9f0d-4719-b32a-dff449be18af

Changes since 4.0

• correct the year of survey for COE single-beam (OBJECTID 25) from 1988 to 1988
• update 2m DEM for Montezuma Slough based on newly connected multibean data by NCRO (August 2018 for Montezuma Slough and Hunter Cut)
• cut the portion of DEM for Calaveras from v3 2m San Joaquin River (dem_calaveras_river_2m_20120902
• Changes only occurs in part 1 of "dem_north_delta_2m_v4_20171220" (v4 final): 1.apply patch at the intersection of Sacramento River and Feather River; 2.add Fremont Weir from the 2m Yolo DEM
• The following modifications are applied to "dem_yolo_merge3_mod_20161202" (v4 final; D:\dem_list_review\yolo_bypass):
• Improved merge with Sacramento River on the north:
• Improved merge with 2m Shag/Stairstep dem (dem_shag_stairstep_toe_drain_2m_v4_beta_20150518.tif ) which goes beyond multibeam data, derived based on mixed single-beam datasets using GAM
• Improved patching and compatibility with USGS 10m release
• Create 2m DEM for the Old River between SWP/CVP to Five points based on new bathymetry data collected in June 2018
• Add the newly developed 2m Montazuma Slough DEM as part of v4 release. Update 10m Delta DEM to be consistent with this addition and update data source polygon accordingly.
• Create 2m DEM for the Old River near Coney Island based on new bathymetry data collected in June 2018
• Incorporate modifications done for Yolo and North Delta into 10m DEM for Delta and Bay-Delta.
• The 20181120 version of the 2m South Delta DEM missed a small region that is included in the old version
• Add LiDAR to Shag Slough in 2m Yolo DEM (dem_yolo_2m_20181012), The existing DEM for Shag Slough did not extend sufficiently over banks.

Digital Elevation Models (DEMs) are digital records of terrain elevations at regularly spaced intervals. The interval between elevations of 7.5 minute DEMs is 30-meters. Each DEM file covers the area of one U.S. Geological Survey 1 to 24,000 scale 7.5 minute topographic quadrangle.

The 36-second Northern California Elevation Grid provides bathymetric data of 36-second resolution in geographic coordinates. This grid is strictly for tsunami inundation modeling

A 1-m resolution, continuous surface, bathymetric digital elevation model (DEM) of the northern portion of San Francisco Bay, which includes San Pablo Bay, Carquinez Strait, and portions of Suisun Bay, was constructed from bathymetric surveys collected from 1999 to 2016. In 2014 and 2015 the California Ocean Protection Council (OPC) contracted the collection of bathymetric surveys of large portions of San Francisco Bay. A total of 93 surveys were collected using a combination of multibeam and interferometric side-scan sonar systems. Of those 93 surveys, 75 consist of swaths of data ranging from 18- to just over 100-meters wide. These swaths were separated by data gaps ranging from 10- to just over 300-meters wide. The no-data areas required interpolation to create a continuous surface. The OPC surveys were combined with additional datasets collected by the United States Geological Survey (USGS), National Oceanic and Atmospheric Administration (NOAA), NOAA’s National Ocean Service (NOS), and the United States Army Corps of Engineers (USACE) to create a continuous, high-resolution digital elevation model (DEM). The creation of this DEM refines techniques developed by the USGS to create DEMs from historic bathymetric data, and allow for the creation of a modern-day bathymetric surface that can be compared to earlier surveys to delineate regions of sediment erosion and deposition.

This product is a digital elevation model (DEM) for the Little Holland Tract in the Sacramento-San Joaquin River Delta, California based on U.S. Geological Survey (USGS)-collected elevation data, merged with existing topographic and bathymetric elevation data. The USGS collected topographic and bathymetric elevation data in 2015, using a combination of methods. Topographic and shallow-water bathymetric data were collected on foot using a global positioning system (GPS) backpack platform that consisted of survey-grade Trimble R10, and Trimble R7 global navigation satellite system (GNSS) receivers with Zephyr 2 antennas. Bathymetric data were collected using a personal watercraft (PWC) platform that consisted of Trimble R7 GNSS receivers with Zephyr 2 antennas, combined with Odom Echotrac CV-100 single-beam echosounders and 200 kHz transducers. The USGS elevation data were merged with topographic aerial Light Detection and Ranging (lidar) data collected by California Department of W ...

Polygon shapefile showing the footprint boundaries, source agency origins, and resolutions of compiled bathymetric digital elevation models (DEMs) used to construct a continuous, high-resolution DEM of the northern portion of San Francisco Bay.

A 1-m resolution, continuous surface, bathymetric digital elevation model (DEM) of the central portion of San Francisco Bay, was constructed from bathymetric surveys collected from 2005 to 2020. In 2014 and 2015 the California Ocean Protection Council (OPC) contracted the collection of bathymetric surveys of large portions of San Francisco Bay. A total of 93 surveys were collected using a combination of multibeam and interferometric side-scan sonar systems. Of those 93 surveys, 75 consist of swaths of data ranging from 18- to just over 100-meters wide. These swaths were separated by data gaps ranging from 10- to just over 300-meters wide. The no-data areas required interpolation to create a continuous surface. The OPC surveys were combined with additional datasets collected by the United States Geological Survey (USGS), National Oceanic and Atmospheric Administration (NOAA), NOAA’s National Ocean Service (NOS), and the United States Army Corps of Engineers (USACE) to create a continuous, high-resolution digital elevation model (DEM). The creation of this DEM refines techniques developed by the USGS to create DEMs from historic bathymetric data, and allow for the creation of a modern-day bathymetric surface that can be compared to earlier surveys to delineate regions of sediment erosion and deposition.

This collection is a legacy product that is no longer supported. It may not meet current government standards. The Canadian Digital Elevation Model (CDEM) is part of Natural Resources Canada's altimetry system designed to better meet the users' needs for elevation data and products. The CDEM stems from the existing Canadian Digital Elevation Data (CDED). In these data, elevations can be either ground or reflective surface elevations. A CDEM mosaic can be obtained for a pre-defined or user-defined extent. The coverage and resolution of a mosaic varies according to latitude and to the extent of the requested area. Derived products such as slope, shaded relief and colour shaded relief maps can also be generated on demand by using the Geospatial-Data Extraction tool. Data can then be saved in many formats. The pre-packaged GeoTiff datasets are based on the National Topographic System of Canada (NTS) at the 1:250 000 scale; the NTS index file is available in the Resources section in many formats.