This is a tiled collection of the 3D Elevation Program (3DEP) and is one meter 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. USGS standard one-meter DEMs are produced exclusively from high resolution light detection and ranging (lidar) source data of one-meter or higher resolution. One-meter DEM surfaces are seamless within collection projects, but, not necessarily seamless across projects. The spatial reference used for tiles of the one-meter DEM within the conterminous United States (CONUS) is Universal Transverse Mercator (UTM) in units of meters, and in conformance with the North American Datum of 1983 (NAD83). All bare earth elevation values are in meters and are referenced to the North American Vertical Datum of 1988 (NAVD88). Each tile is distributed in the UTM Zone in which it lies. If a tile crosses two UTM zones, it is delivered in both zones. The one-meter DEM is the highest resolution standard DEM offered in the 3DEP product suite. Other 3DEP products are nationally seamless DEMs in resolutions of 1/3, 1, and 2 arc seconds. 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. Other 3DEP products include five-meter DEMs in Alaska as well as various source datasets including the lidar point cloud and interferometric synthetic aperture radar (Ifsar) digital surface models and intensity images. All 3DEP products are public domain.

This is a tiled collection of the 3D Elevation Program (3DEP) and is 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 seamless ...

This dataset contains the digital elevation model in Seward Alaska, with 1m vertical resolution and 1-km pixel resolution. This dataset was originally subtracted from United States Geological Survey (USGS) GTOPO30 Dataset, and made appropriate conversion and correction.

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.

This dataset contains the digital elevation model on the North Slope of Alaska, with 1m vertical resolution and 1-km pixel resolution. This dataset was originally subtracted from United States Geological Survey (USGS) GTOPO30 Dataset, and made appropriate conversion and correction.

SUPERSEDED --> See version 4.3 https://data.cnra.ca.gov/dataset/san-francisco-bay-and-sacramento-san-joaquin-delta-dem-for-modeling-version-4-3 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.

The dataset is a 3 m spatial resolution Digital Elevation Model (DEM) representing terrain heights in northern Vicksburg, MS and Vicksburg National Military Park in 1962. The DEM was created using structure from motion-aided (SfM-aided) photogrammetry techniques in Agisoft Metashape (v 2.1.1). The aerial images were acquired on February 10, 1962 by the U.S. Department of Agriculture at approximately 1:18,000 scale by a Fairchild T-12 Number 53-121 camera (9 inch x 9 inch frame) with a Bausch and Lomb Planigon XF6738 lens, calibrated focal length of 152.379. Digitization information is not available, it can be assumed that these photographs were converted to digital by a photogrammetric-quality digital scanning back system operated by the USGS EROS data center. In total 17 frames were downloaded, ranging from 1VAJR00020005 to 1VAJR00020010, from 1VAJR00020026 to 1VAJR00020030, and from 1VAJR00020037 to 1VAJR00020042. Ground reference was established through 16 ground control points (GCPs), with horizontal coordinates acquired from high-resolution orthoimagery (HRO) of Warren County, Mississippi, and vertical elevations acquired from a 1m DEM created from 2020 lidar. The dense point cloud produced by the SfM-aided photogrammetric process was classified to identify points lying on or near the ground; these ground points were then used to interpolate a DEM with a spatial resolution of 91.5 cm. Errors and noise in the DEM surface were reduced through filtering and then resampled to 3 m using bilinear interpolation.

The dataset is a 0.5 m spatial resolution panchromatic orthomosaic of northern Vicksburg, MS and Vicksburg National Military Park in 1962. It was created using structure from motion-aided photogrammetry techniques in Agisoft Metashape (v 2.1.1). The aerial images were acquired on February 10, 1962 by the U.S. Department of Agriculture at approximately 1:18,000 scale by a Fairchild T-12 Number 53-121 camera (9 inch x 9 inch frame) with a Bausch and Lomb Planigon XF6738 lens, calibrated focal length of 152.379. Digitization information is not available, it can be assumed that these photographs were converted to digital by a photogrammetric-quality digital scanning back system operated by the USGS EROS data center. In total 17 frames were downloaded, ranging from 1VAJR00020005 to 1VAJR00020010, from 1VAJR00020026 to 1VAJR00020030, and from 1VAJR00020037 to 1VAJR00020042. Ground reference was established through 16 ground control points, with horizontal coordinates acquired from 6 inch high resolution orthoimagery of Warren County, Mississippi, and vertical elevations acquired from a 1m DEM created from 2020 lidar. The dense point cloud produced by the SfM-aided photogrammetric process was classified to identify points lying on or near the ground; these ground points were then used to interpolate a DEM. The 45.8 cm spatial resolution orthomosaic was then generated using the DEM as the modeling surface.

The aerial images were acquired on June 14, 1938 by Pan American Aerial Surveys for the U.S. Department of Agriculture at approximately 1:20,000 scale by a Fairchild K-10 or similar aerial camera with 5in x 7in frame. The images, archived together with other unrelated aerial imaging projects on film rolls, were accessed at the National Archive in College Park, MD and scanned to digital using an Epson scanner at 2400 dots per inch with 16-bit radiometric resolution. In total 14 frames were scanned, ranging from AVM-3-13 to AVM-3-23A and AVM-2-129 to AVM-2-132. Of these 14 frames, only 4 (AVM-3-19 - AVM-3-122) were found to be useable for SfM-aided DEM generation. Ground reference was established through 83 ground control points, with horizontal coordinates acquired from 6 inch high resolution orthoimagery of Warren County, Mississippi, and vertical elevations acquired from a 1m DEM created from 2020 lidar.

Ground-based readings of temperature and rainfall, satellite imagery, aerial photographs, ground verification data and Digital Elevation Model (DEM) were used in this study. Ground-based meteorological information was obtained from Bangladesh Meteorological Department (BMD) for the period 1977 to 2015 and was used to determine the trends of rainfall and temperature in this thesis. Satellite images obtained from the US Geological Survey (USGS) Center for Earth Resources Observation and Science (EROS) website (www.glovis.usgs.gov) in four time periods were analysed to assess the dynamics of mangrove population at species level. Remote sensing techniques, as a solution to lack of spatial data at a relevant scale and difficulty in accessing the mangroves for field survey and also as an alternative to the traditional methods were used in monitoring of the changes in mangrove species composition, . To identify mangrove forests, a number of satellite sensors have been used, including Landsat TM/ETM/OLI, SPOT, CBERS, SIR, ASTER, and IKONOS and Quick Bird. The use of conventional medium-resolution remote sensor data (e.g., Landsat TM, ASTER, SPOT) in the identification of different mangrove species remains a challenging task. In many developing countries, the high cost of acquiring high- resolution satellite imagery excludes its routine use. The free availability of archived images enables the development of useful techniques in its use and therefor Landsat imagery were used in this study for mangrove species classification. Satellite imagery used in this study includes: Landsat Multispectral Scanner (MSS) of 57 m resolution acquired on 1st February 1977, Landsat Thematic Mapper (TM) of 28.5 m resolution acquired on 5th February 1989, Landsat Enhanced Thematic Mapper (ETM+) of 28.5 m resolution acquired on 28th February 2000 and Landsat Operational Land Imager (OLI) of 30 m resolution acquired on 4th February 2015. To study tidal channel dynamics of the study area, aerial photographs from 1974 and 2011, and a satellite image from 2017 were used. Satellite images from 1974 with good spatial resolution of the area were not available, and therefore aerial photographs of comparatively high and fine resolution were considered adequate to obtain information on tidal channel dynamics. Although high-resolution satellite imagery was available for 2011, aerial photographs were used for this study due to their effectiveness in terms of cost and also ease of comparison with the 1974 photographs. The aerial photographs were sourced from the Survey of Bangladesh (SOB). The Sentinel-2 satellite image from 2017 was downloaded from the European Space Agency (ESA) website (https://scihub.copernicus.eu/). In this research, elevation data acts as the main parameter in the determination of the sea level rise (SLR) impacts on the spatial distribution of the future mangrove species of the Bangladesh Sundarbans. High resolution elevation data is essential for this kind of research where every centimeter counts due to the low-lying characteristics of the study area. The high resolution (less than 1m vertical error) DEM data used in this study was obtained from Water Resources Planning Organization (WRPO), Bangladesh. The elevation information used to construct the DEM was originally collected by a Finnish consulting firm known as FINNMAP in 1991 for the Bangladesh government.