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 North Carolina, Northern 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 Camden, Chowan, Currituck, Gates, Pasquotank, and Perquimans Counties. The DEM was produced from the following lidar data sets: 1. 2014 NGS Coastal Mapping Program Topobathy Lidar: Post-Sandy Atlantic Seaboard 2. 2014 NC Statewide Lidar - Phase 1 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.

Web map displaying Wisconsin DNR-produced Digital Elevation Model (DEM) and Hillshade image services, along with their index layer, in formats that are clickable and can be symbolized and filtered. This map can also be used as a starting point to create a new map. To open the web map from DNR's GIS Open Data Portal, click the View Metadata: link to the right of the description, then click Open in Map Viewer.

1:250000 scale Digital Elevation Model of Arizona. Digital Elevation Model (DEM) is the terminology adopted by the USGS to describe terrain elevation data sets in a digital raster form. The standard DEM consists of a regular array of elevations cast on a designated coordinate projection system. The DEM data are stored as a series of profiles in which the spacing of the elevations along and between each profile is in regular whole number intervals. The normal orientation of data is by columns and rows. Each column contains a series of elevations ordered from south to north with the order of the columns from west to east. The DEM is formatted as one ASCII header record (A-record), followed by a series of profile records (B-records) each of which include a short B-record header followed by a series of ASCII integer elevations per each profile. The last physical record of the DEM is an accuracy record (C-record). A 30-minute DEM (2- by 2-arc second data spacing) consists of four 15-by 15-minute DEM blocks. Two 30-minute DEM's provide the same coverage as a standard USGS 30- by 60-minute quadrangle. Saleable units are 30- by 30-minute blocks, that is, four 15- by 15-minute DEM's representing one half of a 1:100,000-scale map.

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 Florida Northeast 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 Clay, Duval, Flagler, Nassau, Putnam, and St. Johns Counties. The DEM was produced from the following lidar data sets: 1. 2018 Florida Peninsular FDEM - Clay 2. 2018 Florida Peninsular FDEM - Duval 3. 2019 Florida Peninsular - Flagler 4. 2018 Florida Peninsular FDEM - Nassau 5. 2017 City Of Palm Coast, Florida Lidar 6. 2018 Florida Peninsular - Putnam 7. 2018 Florida Peninsular FDEM - St. Johns 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.

This resource contains data inputs and a Jupyter Notebook that is used to introduce Hydrologic Analysis using Terrain Analysis Using Digital Elevation Models (TauDEM) and Python. TauDEM is a free and open-source set of Digital Elevation Model (DEM) tools developed at Utah State University for the extraction and analysis of hydrologic information from topography. This resource is part of a HydroLearn Physical Hydrology learning module available at https://edx.hydrolearn.org/courses/course-v1:Utah_State_University+CEE6400+2019_Fall/about

In this activity, the student learns how to (1) derive hydrologically useful information from Digital Elevation Models (DEMs); (2) describe the sequence of steps involved in mapping stream networks, catchments, and watersheds; and (3) compute an approximate water balance for a watershed-based on publicly available data.

Please note that this exercise is designed for the Logan River watershed, which drains to USGS streamflow gauge 10109000 located just east of Logan, Utah. However, this Jupyter Notebook and the analysis can readily be applied to other locations of interest. If running the terrain analysis for other study sites, you need to prepare a DEM TIF file, an outlet shapefile for the area of interest, and the average annual streamflow and precipitation data. - There are several sources to obtain DEM data. In the U.S., the DEM data (with different spatial resolutions) can be obtained from the National Elevation Dataset available from the national map (http://viewer.nationalmap.gov/viewer/). Another DEM data source is the Shuttle Radar Topography Mission (https://www2.jpl.nasa.gov/srtm/), an international research effort that obtained digital elevation models on a near-global scale (search for Digital Elevation at https://www.usgs.gov/centers/eros/science/usgs-eros-archive-products-overview?qt-science_center_objects=0#qt-science_center_objects). - If not already available, you can generate the outlet shapefile by applying basic terrain analysis steps in geospatial information system models such as ArcGIS or QGIS. - You also need to obtain average annual streamflow and precipitation data for the watershed of interest to assess the annual water balance and calculate the runoff ratio in this exercise. In the U.S., the streamflow data can be obtained from the USGS NWIS website (https://waterdata.usgs.gov/nwis) and the precipitation from PRISM (https://prism.oregonstate.edu/normals/). Note that using other datasets may require preprocessing steps to make data ready to use for this exercise.

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.

In this project, we use the Light Detection and Ranging (LiDAR) data to create the Digital Elevation Model (DEM). The LiDAR data can be downloaded through the Data Access Viewer of NOAA ( https://coast.noaa.gov/dataviewer/#/lidar/search/). For Maui, the majority of the DEM is created using the data of 2013 U.S. Army Corps of Engineers (USACE) National Coastal Mapping Program (NCMP) Topobathy LiDAR – Local Mean Sea Level (LMSL). For some areas not covered by this data set, we use the LiDAR data from 2006 FEMA LiDAR: Hawaiian Islands and 2007 JALBTCX Hawaii LiDAR: North Coasts of Hawaii (Big Island), Kauai, Maui, Molokai, Oahu, which are accessed in the Data Access Viewer of NOAA. Please read “Description of Digital Elevation Model (DEM) for Maui, Hawaii.docx” for detailed information.

This collection of the 3D Elevation Program (3DEP) is at 1/3 arc-second (approximately 10 m) resolution. The 3DEP data holdings serve as the elevation layer of The National Map, and provide foundational elevation information for earth science studies and mapping applications in the United States. Scientists and resource managers use 3DEP data for hydrologic modeling, resource monitoring, mapping and visualization, and many other applications. The elevations in this DEM represent the topographic bare-earth surface. The seamless 1/3 arc-second DEM layers are derived from diverse source data that are processed to a common coordinate system and unit of vertical measure. These data are distributed in geographic coordinates in units of decimal degrees, and in conformance with the North American Datum of 1983 (NAD 83). All elevation values are in meters and, over the continental United States, are referenced to the North American Vertical Datum of 1988 (NAVD88). The vertical reference will vary in other areas. The seamless 1/3 arc-second DEM layer provides coverage of the conterminous United States, Hawaii, Puerto Rico, other territorial islands, and in limited areas of Alaska. These seamless DEMs were referred to as the National Elevation Dataset (NED) from about 2000 through 2015 at which time they became the seamless DEM layers under the 3DEP program and the NED name and system were retired. All 3DEP products are public domain.

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 NOAA Lake Level Viewer. It depicts potential lake level rise and fall 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 lake level change, coastal flooding impacts, and exposed lakeshore. 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 NOAA Lake Level Viewer may be accessed at: https://coast.noaa.gov/llv. This metadata record describes the Lake St. Clair 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 Lake Level 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 Macomb, St. Clair, and Wayne counties in Michigan. The DEM was produced from the following lidar data sets: 1. 2006, USACE NCMP Topobathy Lidar: Lake Erie (OH, PA), Lake Huron (MI) and Lake Michigan (Porter County, IN) 2. 2009, USGS Wayne and Washtenaw County Lidar 3. 2010, ARRA-MI_4SECounties 4. 2012, USACE NCMP Topobathy Lidar: Lake St. Clair (MI) 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.

This resource contains Lidar-DEM collection status shapefiles from the Texas Natural Resources Information System (TNRIS) [http://tnris.org]. November 2023 updates: this year, TNRIS changed its name to Texas Geographic Information Office (TxGIO). The domain name hasn't changed yet, but the data hub is continually evolving. See [1], [2] for current downloadable data.

For purposes of Hurricane Harvey studies, the 1-m DEM for Harris County (2008) has also been uploaded here as a set of 4 zipfiles containing the DEM in tiff files. See [1] for a link to the current elevation status map and downloadable DEMs.
Project name: H-GAC 2008 1m Datasets: 1m Point Cloud, 1M Hydro-Enforced DEM, 3D Breaklines, 1ft and 5ft Contours Points per sq meter: 1 Total area: 3678.56 sq miles Source: Houston-Galveston Area Council (H-GAC) Acquired by: Merrick, QA/QC: Merrick Catalog: houston-galveston-area-council-h-gac-2008-lidar

References: [1] TNRIS/TxGIO StratMap elevation data [https://tnris.org/stratmap/elevation-lidar/] [2] TNRIS/TxGIO DataHub [https://data.tnris.org/]

This is an image service providing access to bathymetric/topographic digital elevation models stewarded at NOAA's National Centers for Environmental Information (NCEI).There are 5 related image services providing access to Digital Elevation Models:DEM Mosaic (Individual DEMs)DEM Global Mosaic (Elevation Values)DEM Global Mosaic (Color Shaded Relief)CUDEM Mosaic (Elevation Values)CUDEM Mosaic (Color Shaded Relief)NCEI builds and distributes high-resolution, coastal digital elevation models (DEMs) that integrate ocean bathymetry and land topography to support NOAA's mission to understand and predict changes in Earth's environment, and conserve and manage coastal and marine resources to meet our Nation's economic, social, and environmental needs. They can be used for modeling of coastal processes (tsunami inundation, storm surge, sea-level rise, contaminant dispersal, etc.), ecosystems management and habitat research, coastal and marine spatial planning, and hazard mitigation and community preparedness. For more information about coastal DEMs at NCEI, please see: https://www.ncei.noaa.gov/products/coastal-elevation-models or learn more from our DEM Fact Sheet (1 MB PDF).This service provides data from many individual DEMs combined together as a mosaic (maximum of 80 rasters at once). By default, the rasters are drawn in order of cell size, with higher-resolution grids displayed on top of lower-resolution grids. If overlapping DEMs have the same resolution, the newer one is shown. Alternatively, a single DEM or group of DEMs can be isolated using a filter/definition query or using the "Lock Raster" mosaic method in ArcMap.The DEMs can be viewed in NCEI's Bathymetric Data Viewer along with other bathymetric datasets stewarded at NCEI.Please see NCEI's corresponding DEM Footprints map service for polygon footprints and more information about the individual DEMs used to create this composite view. The newer 1/3 and 1/9 arcsecond "tiled" DEMs are hosted by NOAA's Office for Coastal Management; please see the Data Access Viewer for access to these data. View these services together in a single combined map.This service has a server-side function available. This can be selected in the ArcGIS Online layer using "Image Display", or in ArcMap under "Processing Templates".None: The default. Provides elevation/depth values in meters. Please refer to the vertical datum for each DEM.ColorHillshade: An elevation-tinted hillshade visualization. The depths are displayed using this color ramp:THREDDS catalog (for extracting/downloading DEMs)

A 10-meter resolution land surface digital elevation model (DEM) for the islands of Palau from U.S. Geological Survey (USGS) 1/3 arc-second DEM quadrangles. For a grayscale hillshade image layer of this dataset, see "pw_usgs_all_dem10m_hillshade" in the distribution links listed in the metadata. acknowledgement=The Pacific Islands Ocean Observing System (PacIOOS) is funded through the National Oceanic and Atmospheric Administration (NOAA) as a Regional Association within the U.S. Integrated Ocean Observing System (IOOS). PacIOOS is coordinated by the University of Hawaii School of Ocean and Earth Science and Technology (SOEST). cdm_data_type=Grid comment=These data are provided by USGS and subsequently distributed via THREDDS Data Server (TDS) and ERDDAP by PacIOOS. Conventions=CF-1.6, ACDD-1.3 date_metadata_modified=2023-01-20 drawLandMask=off Easternmost_Easting=134.64967501368815 geospatial_bounds=POLYGON ((6.874626 134.096848, 7.754260 134.096848, 7.754260 134.693147, 6.874626 134.693147, 6.874626 134.096848)) geospatial_bounds_crs=EPSG:4326 geospatial_lat_max=7.754213715821437 geospatial_lat_min=6.874765028140425 geospatial_lat_resolution=9.25930393431261E-5 geospatial_lat_units=degrees_north geospatial_lon_max=134.64967501368815 geospatial_lon_min=134.09689456880972 geospatial_lon_resolution=9.259303934312171E-5 geospatial_lon_units=degrees_east history=2015-05-11T00:00:00Z PacIOOS obtained ArcInfo Binary Grids from The National Map Viewer of USGS then mosaicked and converted to NetCDF format and EPSG:4326 spatial reference system. id=usgs_dem_10m_palau infoUrl=https://www.usgs.gov/core-science-systems/national-geospatial-program/national-map institution=U.S. Geological Survey (USGS) instrument=Not Applicable > Not Applicable instrument_vocabulary=GCMD Instrument Keywords ISO_Topic_Categories=elevation keywords_vocabulary=GCMD Science Keywords locations=Ocean > Pacific Ocean > Western Pacific Ocean > Micronesia > Palau locations_vocabulary=GCMD Location Keywords metadata_link=https://www.pacioos.hawaii.edu/metadata/usgs_dem_10m_palau.html naming_authority=org.pacioos Northernmost_Northing=7.754213715821437 platform=Models/Analyses > > DEM > Digital Elevation Model platform_vocabulary=GCMD Platform Keywords program=Pacific Islands Ocean Observing System (PacIOOS) project=Pacific Islands Ocean Observing System (PacIOOS) references=https://www.pacioos.hawaii.edu/metadata/pw_usgs_all_dem10m_hillshade.html source=USGS 1/3 arc-second DEM quadrangles sourceUrl=https://pae-paha.pacioos.hawaii.edu/thredds/dodsC/usgs_dem_10m_palau Southernmost_Northing=6.874765028140425 standard_name_vocabulary=CF Standard Name Table v39 time_coverage_duration=P0D time_coverage_resolution=P0D Westernmost_Easting=134.09689456880972

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 New York, Hudson River 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 Albany, Columbia, Dutchess, Greene, Orange, Putnam, Rensselaer, and Ulster Counties. The DEM was produced from the following lidar data sets: 1. 2011-2012 New York Coastal Lidar 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.

This dataset contains the Digital Elevation Model (DEM) for South America from the Hydrologic Derivatives for Modeling and Analysis (HDMA) database. The data were developed and distributed by processing units. There are 10 processing units for South America. The distribution files have the number of the processing unit appended to the end of the zip file name (e.g. sa_dem_3.zip contains the DEM data for unit 3-2). The HDMA database provides comprehensive and consistent global coverage of raster and vector topographically derived layers, including raster layers of digital elevation model (DEM) data, flow direction, flow accumulation, slope, and compound topographic index (CTI); and vector layers of streams and catchment boundaries. The coverage of the data is global (-180º, 180º, -90º, 90º) with the underlying DEM being a hybrid of three datasets: HydroSHEDS (Hydrological data and maps based on SHuttle Elevation Derivatives at multiple Scales), Global Multi-resolution Terrain Eleva ...

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 Louisiana Central East 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 Ascension, Assumption, Iberville, Lafourche, St. James, Terrebonne, and West Baton Rouge Parishes. The DEM was produced from the following lidar data sets: 1. 2017 Upper Delta Plain LA Lidar 2. 2015 South Terrebonne Lidar 3. 2012 - 2013 USGS Louisiana Lidar: Atchafalaya Basin 4. 2013 USGS Louisiana Barataria Lidar 5. 2006 LA Statewide Lidar The DEM is referenced vertically to the North American Vertical Datum of 1988 (NAVD88, Geoid12B) with vertical units of meters and horizontally to the North American Datum of 1983 (NAD83). The resolution of the DEM is approximately 3 meters.

This is a feature layer showing the location and coverage of land and seafloor digital elevation models (DEMs) available from NOAA's National Centers for Environmental Information (NCEI).NOAA/NCEI builds and distributes high-resolution coastal digital elevation models (DEMs) that integrate ocean bathymetry and land topography to support NOAA's mission to understand and predict changes in Earth's environment, and conserve and manage coastal and marine resources to meet our Nation's economic, social, and environmental needs. They can be used for modeling of coastal processes (tsunami inundation, storm surge, sea-level rise, contaminant dispersal, etc.), ecosystems management and habitat research, coastal and marine spatial planning, and hazard mitigation and community preparedness.For more information about coastal DEMs at NCEI, please see: https://www.ncei.noaa.gov/products/coastal-elevation-models or learn more from our DEM Fact Sheet (1 MB PDF).This layer can be viewed in NCEI's Bathymetric Data Viewer along with other bathymetric datasets stewarded at NCEI.THREDDS catalog (for extracting/downloading DEMs)

(Link to Metadata) VTHYDRODEM was created to produce a "hydrologically correct" DEM, compliant with the Vermont Hydrography Dataset (VHD) in support of the "flow regime" project whose goal it is to derive stream perenniality for the VHD through application of logistic regression techniques. Some very important notes about the data: 1)Produced specifically for hydrologic modeling purposes and elevation surface has been altered and should not be used for analyses requiring unmodified elevation values; 2) ELEVATION VALUES, i.e., "Z units", are in CENTIMETERS (details below); and 3) Source data spans a five year period where varying techniques were used. This may explain observed inconsistencies both between and within tiles (detailed in the Attribute Accuracy Report below). This dataset has elevation values present in the surface that accurately reflect the down gradient nature and location of surface water features, i.e. the VHD. This process is also known as "hydro-enforcement" or "drainage enforcement". It is largely unknown that the 1:24k scale National Elevation Dataset (NED) is not "hydrologically correct" in relation to the National Hydrography Dataset (NHD) vector data of the same scale, e.g., the flow paths in the NED surface are not perfectly coincident to those in the scale NHD surface water features. This fact precluded the use of the NED data for hydrologic modeling efforts and reaffirmed the need to create a new "hydrologically correct" DEM. All processing was done using ARCINFO workstation (v.8.3) commands. The ARCINFO "TOPOGRID" command was used to create VTHYDRODEM as it was specifically designed to create "hydrologically correct" digital elevation models (DEM's) from elevation, stream and lake data sets. Single line "1D" streams and lake/pond "2D" polygons, from the 1:5k scale VHD, were given priority over input elevation data in the interpolation process to ensure that the resulting data is "hydrologically correct". Both the VHD and VTHYDRODEM share a common base of the state digital orthophotos, ensuring their interoperability. The Triangulated Irregular Networks (TIN) method was not considered but interested readers should review West Virginia's approach http://www.wvgis.wvu.edu/stateactivities/wvsamb/elevation/topogrid_vs_tin.pdf. This report notes the advantages and disadvantages of each approach. It should be noted that the WV effort included more recent imagery, and a much tighter sampling interval of source data. Nonetheless, it makes a strong case for the TIN approach that should be considered in any subsequent DEM development efforts. The density of input points used to create VTHYDRODEM was lower than the 1:24k NED but the vertical accuracy of those points tested at a higher accuracy and these points were generated with less variability in technique than that of the NED (see http://gisdata.usgs.net/website/USGS_GN_NED_DSI/viewer.htm and check "production methods" under "Layers" for NED data sources and methods). Vertical accuracy was derived using the FGDC National Standards for Spatial Data Accuracy (NSSDA) standards. For the sake of comparison, VTHYDRODEM tested at 6.05 meters, vertical accuracy at the 95% confidence level, whereas, the 1:24k National Elevation Dataset (DEM_24) tested at 21.3 meters. VTHYDRODEM was created for a specific, in-house project to support hydrologic modeling activities using the 1:5k scale VHD. It was interpolated from: 1) the Vermont Mapping Program (VMP) "x, y, z" data known as the "DEM points" (originally used to georectify the state digital orthophotos); and 2) VHD surface water features. A 10-meter cell resolution was chosen for VTHYDRODEM as a balance between input data accuracy and practical considerations and does not necessarily reflect the accuracy of the input data. The 10-meter resolution of this dataset was chosen arbitrarily for reasons noted below and should not be confused with an accuracy of 10 meters. This data should not be confused with the "1/3 arc second" 10m NED data. The lower 10m cell resolution has the following advantages when compared to the existing 30m 1:24k NED: 1) Stream confluences (junctions) can be defined with a greater degree of precision; 2) Confluences in close proximity can be represented individually; 3) Smaller landscape features can be represented and larger ones in greater detail; 4) Exponential improvement in volumetric measurement and tripling of precision in linear measurement of derived vector features, e.g., a watershed boundary is composed of aggregated 10m, i.e., 3 cells equals 30m vs. 30m resolution where 3 cells equals 90m. Similarly the concept applies to volumetric measurements); and 5) Improved cartographic accuracy for derived vector features. NOTE! Elevation units, e.g., "Z units" are in CENTIMETERS. This seeming arbitrary decision has a number of advantages worth considering. The output grid can now be stored as an "integer" type grid while simultaneously preserving the precision of the input data to the nearest centimeter. Integer type grids require one-tenth the storage space and are consequently much faster to process, e.g., deriving watershed boundaries. While it is unlikely that the input data is accurate to the nearest centimeter, this approach allows for greater precision storage, improves the overall appearance of the DEM and precludes problems with the model's depiction of over land flow in hydrologic related analyses when compared to coarser vertical resolutions. This approach mirrors a trend among the USGS and its contractors, who are now producing DEM's with a vertical resolution of decimeters (0.1 meter) for the benefits outlined above.

These data depict the elevation features of Konza Prairie. Record type 1 is a 2 meter resolution digital elevation model (DEM) of Konza Prairie, generated from 2006 LiDAR DEM data collected to standard USGS specifications (GIS200). Record type 3 is a 2010 10 meter (1/3 arc second) resolution National Elevation Dataset (NED) DEM of Konza Prairie (GIS202). Record type 4 is a 10 meter resolution NED DEM of Konza Prairie with a modified 3 kilometer buffer (GIS203). Record type 5 is a USGS topographic map of Konza Prairie (GIS204). These data are available as zipped (.zip) TIFF files (.tif). Data and metadata derived from DASC (record types 1 and 5), http://www.kansasgis.org/. Additional data and metadata derived from USGS (record types 3 and 4), http://www.nationalmap.gov/viewer.html.

The DEM Global Mosaic is an image service providing a global, seamless bathymetry/topography mosaic that includes NCEI's ETOPO 2022, NCEI's Continuously Updated DEM (CUDEM), and other NCEI-stewarded DEMs, along with regional grids such as IBCAO, IBCSO, and the Hawaiian Island Multibeam Synthesis (University of Hawaii). This service provides elevation/depth values in meters; for a visualization of the data, please see the related DEM Global Mosaic (Color Shaded Relief) service.There are 5 related image services providing access to Digital Elevation Models:DEM Mosaic (Individual DEMs)DEM Global Mosaic (Elevation Values)DEM Global Mosaic (Color Shaded Relief)CUDEM Mosaic (Elevation Values)CUDEM Mosaic (Color Shaded Relief)NCEI builds and distributes high-resolution, coastal digital elevation models (DEMs) that integrate ocean bathymetry and land topography to support NOAA's mission to understand and predict changes in Earth's environment, and conserve and manage coastal and marine resources to meet our Nation's economic, social, and environmental needs. They can be used for modeling of coastal processes (tsunami inundation, storm surge, sea-level rise, contaminant dispersal, etc.), ecosystems management and habitat research, coastal and marine spatial planning, and hazard mitigation and community preparedness. For more information about coastal DEMs at NCEI, please see: https://www.ncei.noaa.gov/products/coastal-elevation-models or learn more from our DEM Fact Sheet (1 MB PDF).This service is a general-purpose global, seamless bathymetry/topography mosaic. It combines DEMs from a variety of near sea-level vertical datums, such as mean high water (MHW), mean sea level (MSL), and North American Vertical Datum of 1988 (NAVD88). No conversion/harmonization of vertical datums was performed. Because the mosaic contains "overviews" for performance, individual DEMs cannot be separated from the others. Individual DEMs, or smaller subsets, are available in the companion DEM Mosaic (Individual DEMs) image service.By default, the DEMs are drawn in order of cell size, with higher-resolution grids displayed on top of lower-resolution grids. If overlapping DEMs have the same resolution, the newer one is shown.The DEMs can be viewed in NCEI's Bathymetric Data Viewer along with other bathymetric datasets stewarded at NCEI.Please see NCEI's corresponding DEM Footprints map service for polygon footprints and more information about the individual DEMs used to create this composite view. The newer 1/3 and 1/9 arcsecond "tiled" DEMs are hosted by NOAA's Office for Coastal Management; please see the Data Access Viewer for access to these data.THREDDS catalog (for extracting/downloading DEMs)

Topographic and bathymetric data were collected for the Duplin River and adjacent intertidal areas near Sapelo Island, Georgia, using high-precision multibeam SONAR equipment. The bathymetric survey was performed from 09-Dec-2009 to 12-Dec-2009. This study was conducted to create a base map of bathymetry, morphology and physical habitat of the Duplin River, which is a primary study site of the Georgia Coastal Ecosystems Long Term Ecological Research (GCE-LTER) project.