[Metadatas] This layer represents the USGS topo quadrangle boundaries published in the Old Hawaiian Datum (OHD), prior to their being recast in the late 1990's. Source: Created by the Office of State Planning in the Old Hawaiian Datum using the latitude/longitude coordinates of the quadrangle boundaries, and the ARC GENERATE command.

For more information, see the full metadata at https://files.hawaii.gov/dbedt/op/gis/data/usgs_quads_ohd.pdf, or contact the Hawaii Statewide GIS Program, Office of Planning and Sustainable Development, State of Hawaii; PO Box 2359, Honolulu, Hi. 96804; (808) 587-2846; email: gis@hawaii.gov; Website: https://planning.hawaii.gov/gis.

[Metadata] Geoid 12B: Hybrid geoid model used to convert the ellipsoidal height obtained by the Global Navigation Satellite System (to the orthometric height of a specific vertical datum). The National Geodetic Survey (NGS) has been producing the hybrid geoid to convert the ellipsoidal height obtained from the Global Navigation Satellite System (GNSS) to the orthometric height of a specific vertical datum. The GEOID12B model is intended to transform between NAD 83 (2011/PA11/MA11) and the respective vertical datums for the different regions, including NAVD88, GUVD04, ASVD02, NMVD03, PRVD02 and VIVD09.

This study is the first comprehensive publication of tidal datums and extreme tides for San Francisco Bay (Bay) since the United States Army Corps of Engineers (USACE) published itsSan Francisco Bay Tidal Stage vs. Frequency Study in 1984 (USACE 1984). The USACE study was groundbreaking at the time of publication, presenting tidal datums and the “100-year tide” elevation for 53 locations around the Bay. The purpose of this study is to update and expand on the USACE study and to present daily and extreme tidal information for more than 900 locations along the Bay shoreline. Tidal datums, described further in Section 2 , are standard elevations defined by a certain phase of the tide (e.g., mean high tide, mean low tide). A tidal datum is used as a reference to measure and define local water levels, and as such is specific to local hydrodynamic processes and is not easily extended from one area to another without substantiating measurements or analysis. Many industries and activities rely on tidal datums, including shipping and navigation, coastal flood management, coastal development, and wetland restoration. Extreme tidal elevations are estimated for less-frequent extreme tides (e.g., 2-year tides to 500-year tides [tides with a 50.0 percent to 0.2 percent annual chance of occurrence, respectively]). Knowledge of the 100-year tide, or the water elevation with a 1 percent annual chance of occurrence, is critical for shoreline planning, floodplain management, and sea level rise (SLR) adaptation efforts. This study presents detailed daily and extreme tide information for the entirety of the Bay shoreline. This data set will support floodplain management efforts; shoreline vulnerability and risk analyses; shoreline engineering, design, and permitting; ecological studies; and appropriate sea level rise adaptation planning. The goal of this study is to provide data that support a wide-range of planning efforts around the Bay, particularly as communities seek to understand—and begin to adapt to—rising sea levels. You can access the full report at: http://www.adaptingtorisingtides.org/wp-content/uploads/2016/05/20160429.SFBay_Tidal-Datums_and_Extreme_Tides_Study.FINAL_.pdf.

This map represents City of Salem, Oregon, Survey Benchmarks. The Survey Section of the Public Works Department establishes and maintains horizontal and vertical survey control throughout the City for most public and private projects. Vertical datum is NGVD 1929-47. Horizontal datum is NAD 1983-91. The map references detailed GIS data provided by the City of Salem Public Works Department. Contact the City of Salem City Surveyor (503-588-6211) for questions and the most up-to-date information, or gis@cityofsalem.net.

Tidal Datum GIS outputsShapefiles are provided that present the approximate shore-parallel extent of tidal datums across coastal Massachusetts. These shapefiles are provided for 2030, 2050, and 2070 sea level rise scenarios. Individual shapefiles are provided for the north and south model domains for a total of 6 tidal datum shapefiles (2 model domains, 3 sea level rise scenarios). The results presented within these polygons are based upon tidal model simulations conducted using the MC-FRM, with north shapefiles created using the north model domain, and south using the south model domain. Separate polygons (zones) are provided for approximate location where MHW values vary to the nearest 0.1 ft interval. These zones are derived based on the variation in the MHW datum, and as such other datums (MHHW, MTL, MLW, and MLLW) may vary withineach segmented polygon, especially in areas of varied bathymetry. Data are presented in units of feet relative to the NAVD88 datum.These shapefiles contain the following fields: FID, Shape, Hatch, MHHW, MHW, MTL, MLW, and MLLW. The MHHW, MHW, MTL, MLW, and MLLW fields contain float type values representing the tidal datums calculated for each polygon rounded to the nearest tenth of a foot. The Hatch field contains a binary value (0 or 1), with 1 representing zones of uncertainty for tidal datums. These uncertain zones are either dynamic in terms of geomorphology or are restricted by smaller anthropogenic features (culverts, tide gates, etc.) that were not fully resolved in the MC-FRM. Zones with a 1 Hatch value may or may not contain tidal datum information. It is recommended that care be taken when utilizing the tidal benchmark information in these hatched zones and site-specific data observations (tide data) are recommended to verify the values in these areas. If datum information is not available 9999 values are located in the datum fields for that polygon. The FID and Shape fields contain an ID number and shape type contained in each polygon.The shapefiles provided are not intended to represent a spatial extent of the tidal benchmark (i.e., they do not present the geospatial location of water level). Rather, these shapefiles provide the tidal benchmark values that should be applied over each of the geospatial zones.

The following dataset includes "Active Benchmarks," which are provided to facilitate the identification of City-managed standard benchmarks. Standard benchmarks are for public and private use in establishing a point in space. Note: The benchmarks are referenced to the Chicago City Datum = 0.00, (CCD = 579.88 feet above mean tide New York). The City of Chicago Department of Water Management’s (DWM) Topographic Benchmark is the source of the benchmark information contained in this online database. The information contained in the index card system was compiled by scanning the original cards, then transcribing some of this information to prepare a table and map. Over time, the DWM will contract services to field verify the data and update the index card system and this online database.This dataset was last updated September 2011. Coordinates are estimated. To view map, go to https://data.cityofchicago.org/Buildings/Elevation-Benchmarks-Map/kmt9-pg57 or for PDF map, go to http://cityofchicago.org/content/dam/city/depts/water/supp_info/Benchmarks/BMMap.pdf. Please read the Terms of Use: http://www.cityofchicago.org/city/en/narr/foia/data_disclaimer.html.

These data are a derived product of the NOAA VDatum tool and they extend the tool's Mean Higher High Water (MHHW) tidal datum conversion inland beyond its original extent. VDatum was designed to vertically transform geospatial data among a variety of tidal, orthometric and ellipsoidal vertical datums - allowing users to convert their data from different horizontal/vertical references into a common system and enabling the fusion of diverse geospatial data in desired reference levels (http://vdatum.noaa.gov/). However, VDatum's conversion extent does not completely cover tidally-influenced areas along the coast. For more information on why VDatum does not provide tidal datums inland, see http://vdatum.noaa.gov/docs/faqs.html. Because of the extent limitation and since most inundation mapping activities use a tidal datum as the reference zero (i.e., 1 meter of sea level rise on top of Mean Higher High Water), the NOAA Office for Coastal Management created this dataset for the purpose of extending the MHHW tidal datum beyond the areas covered by VDatum. The data do not replace VDatum, nor do they supersede the valid datum transformations VDatum provides. However, the data are based on VDatum's underlying transformation data and do provide an approximation of MHHW where VDatum does not provide one. In addition, the data are in a GIS-friendly format and represent MHHW in NAVD88, which is the vertical datum by which most topographic data are referenced. Data are in the UTM NAD83 projection. Horizontal resolution varies by VDatum region, but is either 50m or 100m. Data are vertically referenced to NAVD88 meters.

The California Department of Water Resources (DWR), North Central Region Office (NCRO), Bathymetry Data Collection Section, conducted a bathymetric survey of Suisun Slough for the Bay Delta Office (BDO). The main purpose of the data is to replace outdated and inaccurate data, help with the evaluation of a large number of restoration proposals nearby, and inform the re-operation of the Montezuma Slough Salinity Control Structure for the Delta Smelt Resiliency Strategy being implemented in 2018. • Survey Dates: February 19-20 • Vessels Used: NCRO R/V KingFisher• Instrumentation: Singlebeam echo sounder with Inertially-Aided Post-Processed Kinematic (IAPPK) GPS procedures. • Point Spacing: about 1 foot • Horizontal Datum: North American Datum of 1983 (NAD83) California Coordinate System (CCS83) State Plane Zone III , US feet• Vertical Datum: North American Vertical Datum of 1988 (NAVD88), US feet• Process Date Epoch: 2020.137 Datum Epoch: 2017.5• Involved Staff: Data collected and processed by NCRO Bathymetry sections• Survey Responsible Charge: Jacob Wright, PLS (CA 8717)For complete metadata make sure the viewer (ArcGIS or other software) is set to view FGDC metadata.

To map the predicted sea level rise for Barnstable County (Cape Cod) the most accurate elevation data was obtained and adjusted to account for vertical datum variations as well as localized tidal information. This adjusted data, was then separated into areas below sea level and into 1 ft increments (up to 6ft) above sea level. Topographical elevation data was sourced from remotely sensed LiDAR data which was collected in the Winter and Spring of 2011, while no snow was on the ground, rivers were at or below normal levels and within 90 minutes of the daily predicted low tide. For Barnstable County, the LiDAR was processed and classified to meet a bare earth Fundamental Vertical Accuracy (FVA) of 18.13 cm at a 95% confidence level. The topological elevation data was in a grid format, as a Digital Elevation Model (DEM) with a cell size of 1 meter. In order to incorporate tidal variability within an area when mapping sea level rise, a “modeled” surface (or raster) is needed that represents this variability. In addition, this surface must be represented in the same vertical datum as the elevation data. To account for the datum and tidal differences across the county the DEM was adjusted to localized conditions using the NOAA VDatum (Verticle Datum Transformation) software. The VDatum program was used to convert a 500m grid of points that covered the entire Barnstable County area from the source of North American Vertical Datum 88 (NAVD 88) to Mean Higher High Water (MHHW). MHHW is the average of the higher high water height of each tidal day observed over the National Tidal Datum Epoch. The 500m MHHW grid was then interpolated into a 1m grid that was identical in spatial extent to the 1m topographical DEM. The topographical DEM was then adjusted on a cell-by-cell basis to account for the MHHW elevation.

This is a point data set representing monumented vertical geodetic survey control points (a.k.a. elevation benchmarks) established by the City of Boise. A benchmark is a physical marker, monument, or demarcation established by a surveyor for horizontal and/or vertical measurement control. This data set only contains benchmarks established by the City of Boise that are based on the North American Vertical Datum of 1988 (NAVD 88); benchmarks established under other vertical datums are not included. The elevation values in this data set are based on the vertical control from the National Geodetic Survey (NGS), the U. S. Geological Survey (USGS), and some state owned vertical control. The horizontal location is obtained by Global Positioning System (GPS) data collection of the surveyed benchmark. Attribute data including elevation, is transcribed from surveying field books supplied by Boise City Public Works survey personnel. Data Attributes:MARK TYPE: ALCAP - Aluminum Cap, BRASSCAP - Brass Cap, CHISELSQ - physically carved square, PK - A steel masonry nail manufactured by Parker Kaelon (PK nail), OTHER - Any other survey marker type.LOCATION: Nearest street or cross streets to the benchmark.ELEVATION: The vertical elevation in feet above sea level as established from survey calculations based on the 1988 NAVD Datum.GPS DATE: Date the benchmark was captured by GPS.COMMENTS: Pertinent notes on general description and location of the benchmark.BOOK: The City of Boise Public Works surveying field book number the benchmark was established under.PAGE: The City of Boise Public Works surveying field book page the benchmark was established under.The data set is maintained by the Boise City Public Works GIS staff. The data is updated continuously. It is current to the date it was published.For more information, please visit Ada County Control Information or City of Boise Public Works.

The California Department of Water Resources (DWR), North Central Region Office (NCRO), Bathymetry Data Collection Section, conducted a bathymetric survey of Middle River south of Union Point as part of the Delta Wide Bathymetry Program. The main purpose of the data is to help complete bathymetric datasets of Suisun Marsh and the Sacramento-San Joaquin Delta and allow for relevant comparisons. • Field Dates: July 13-20, 2023 • Survey Type: Singlebeam • Data Density: 1 foot spacing• Horizontal Datum: North American Datum of 1983 (NAD83) California Coordinate System (CCS83) State Plane Zone III, US ft • Vertical Datum: North American Vertical Datum of 1988 (NAVD88), US ft • Process Epoch: 2023.551; Datum Epoch: 2017.5 • Related Datasets: Middle River, March 2017 • Involved Staff: Data collected and processed by NCRO Bathymetry and Hydrography sections • Survey Responsible Charge: Jacob Wright, PLS (CA 8717) For complete metadata make sure the viewer (ArcGIS or other software) is set to view FGDC metadata.

In Spring 2019, with funding from several State partners, MassGIS contracted with the U.S. Geological Survey for statewide, 15 cm resolution, 16-bit, 4-band (RGB-IR) digital orthophotos. The data were delivered in early 2020 as 10,218 individual 1,500 m x 1,500 m tiles in a GeoTIFF format. To allow for easier distribution of this free imagery, MassGIS compressed the GeoTIFFS into the JPEG 2000 format, which retains the IR band. The tile naming convention is based on the U.S. National Grid (USNG), taking the coordinates of the southwest corner of the tile.Project specifications are based on the American Society of Photogrammetry and Remote Sensing (ASPRS) standards. The data were developed based on a horizontal projection/datum of NAD 1983 2011 UTM zones 18N and 19N meters and a vertical projection/datum of NAVD 88 (GEOID 12B) meters.This digital orthoimagery was created to provide easily accessible geospatial data which are readily available to enhance the capability of federal, state, and local emergency responders, as well as to plan for homeland security efforts. These data also support The National Map.These images can serve a variety of purposes, from general planning to field reference for spatial analysis, to a tool for data development and revision of vector maps. The imagery can also serve as a reference layer or basemap for myriad applications inside geographic information system (GIS) software and web-based maps.This image service was created using JPEG 2000 versions of the imagery that MassGIS converted from GeoTiffs and distributes online.For more information see the imagery's MassGIS metadata page.

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).The DEM Global Mosaic is an image service providing access to bathymetric/topographic digital elevation models stewarded at NOAA's National Centers for Environmental Information (NCEI), along with the global GEBCO_2014 grid: http://www.gebco.net/data_and_products/gridded_bathymetry_data. 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. 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). Elevation values have been rounded to the nearest meter, with DEM cell sizes going down to 1 arc-second. Higher-resolution DEMs, with greater elevation precision, are available in the companion NAVD88: http://noaa.maps.arcgis.com/home/item.html?id=e9ba2e7afb7d46cd878b34aa3bfce042 and MHW: http://noaa.maps.arcgis.com/home/item.html?id=3bc7611c1d904a5eaf90ecbec88fa799 mosaics. 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. Please see NCEI's corresponding DEM Footprints map service: http://noaa.maps.arcgis.com/home/item.html?id=d41f39c8a6684c54b62c8f1ab731d5ad for polygon footprints and more information about the individual DEMs used to create this composite view. In this visualization, the elevations/depths are displayed using this color ramp: http://gis.ngdc.noaa.gov/viewers/images/dem_color_scale.png.A map service showing the location and coverage of land and seafloor digital elevation models (DEMs) available from NOAA's National Centers for Environmental Information (NCEI). 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. Layers available in the map service: Layers 1-4: DEMs by Category (includes various DEMs, both hosted at NCEI, and elsewhere on the web); Layers 6-11: NCEI DEM Projects (DEMs hosted at NCEI, color-coded by project); Layer 12: All NCEI Bathymetry DEMs (All bathymetry or bathy-topo DEMs hosted at NCEI).This is an image service providing access to bathymetric/topographic digital elevation models stewarded at NOAA's National Centers for Environmental Information (NCEI), with vertical units referenced to mean high water (MHW). 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. This service provides data from many individual DEMs combined together as a mosaic. 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. This is one of three services displaying collections of DEMs that are referenced to common vertical datums: North American Vertical Datum of 1988 (NAVD88): http://noaa.maps.arcgis.com/home/item.html?id=e9ba2e7afb7d46cd878b34aa3bfce042, Mean High Water (MHW): http://noaa.maps.arcgis.com/home/item.html?id=3bc7611c1d904a5eaf90ecbec88fa799, and Mean Higher High Water: http://noaa.maps.arcgis.com/home/item.html?id=9471f8d4f43e48109de6275522856696. In addition, the DEM Global Mosaic is a general-purpose global, seamless bathymetry/topography mosaic containing all the DEMs together. Two services are available: http://noaa.maps.arcgis.com/home/item.html?id=c876e3c96a8642ab8557646a3b4fa0ff Elevation Values: http://noaa.maps.arcgis.com/home/item.html?id=c876e3c96a8642ab8557646a3b4fa0ff and Color Shaded Relief: http://noaa.maps.arcgis.com/home/item.html?id=feb3c625dc094112bb5281c17679c769. Please see the corresponding DEM Footprints map service: http://noaa.maps.arcgis.com/home/item.html?id=d41f39c8a6684c54b62c8f1ab731d5ad for polygon footprints and more information about the individual DEMs used to create this composite view. This service has several server-side functions available. These 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 relative to the NAVD88 vertical datum. ColorHillshade: An elevation-tinted hillshade visualization. The depths are displayed using this color ramp: http://gis.ngdc.noaa.gov/viewers/images/dem_color_scale.png. GrayscaleHillshade: A simple grayscale hillshade visualization. SlopeMapRGB: Slope in degrees, visualized using these colors: http://downloads.esri.com/esri_content_doc/landscape/SlopeMapLegend_V7b.png. SlopeNumericValues: Slope in degrees, returning the actual numeric values. AspectMapRGB: Orientation of the terrain (0-360 degrees), visualized using these colors: http://downloads.esri.com/esri_content_doc/landscape/AspectMapLegendPie_V7b.png. AspectNumericValues: Aspect in degrees, returning the actual numeric values.

The Christmas Island Geographic Information System (CIGIS) is a collection of spatial data, viewing and analysis tools dealing with Christmas Island, Indian Ocean. The data include orthophotography, topographic, mining, cultural and environmental features of the island. This work is part of ongoing service to the Department of Transport and Regional Services.

[Metadata] NGS Geodetic Control Stations: This data contains a set of geodetic control stations maintained by the National Geodetic Survey. Downloaded by the Hawaii Statewide GIS Program from NGS, 1/28/22. Each geodetic control station in this dataset has either a precise Latitude/Longitude used for horizontal control or a precise Orthometric Height used for vertical control, or both. The National Geodetic Survey (NGS) serves as the Nation's depository for geodetic data. The NGS distributes geodetic data worldwide to a variety of users. These geodetic data include the final results of geodetic surveys, software programs to format, compute, verify, and adjust original survey observations or to convert values from one geodetic datum to another, and publications that describe how to obtain and use Geodetic Data products and services. Note: This data was projected to the State's standard projection/datum of UTM Zone 4, NAD 83 HARN for use in the State's GIS database, The State posts an un-projected version of the layer on its legacy site (https://planning.hawaii.gov/gis/download-gis-data-expanded/#013), or users can visit the National Geodetic Survey site directly, at https://www.ngs.noaa.gov/cgi-bin/sf_archive.prl. For additional information, please see metadata at https://files.hawaii.gov/dbedt/op/gis/data/ngs_geodetic_ctrl_stns_summary.pdfor contact Hawaii Statewide GIS Program, Office of Planning and Sustainable Development, State of Hawaii; PO Box 2359, Honolulu, Hi. 96804; (808) 587-2846; email: gis@hawaii.gov; Website: https://planning.hawaii.gov/gis.

This 1m Digital Terrain Model (DTM) is derived from bare-ground Light Detection and Ranging (LiDAR) point cloud data from September 2005 for the Green Lakes Valley, near Boulder Colorado. This dataset is better suited for derived layers such as slope angle, aspect, and contours. The DTM was created from LiDAR point cloud tiles subsampled to 1-meter postings, acquired by the National Center for Airborne Laser Mapping (NCALM) project. This data was collected in collaboration between the University of Colorado, Institute of Arctic and Alpine Research (INSTAAR) and NCALM, which is funded by the National Science Foundation (NSF). The DTM has the functionality of a map layer for use in Geographic Information Systems (GIS) or remote sensing software. Total area imaged is 35 km^2. The LiDAR point cloud data was acquired with an Optech 1233 Airborne Laser Terrain Mapper (ALTM) and mounted in a twin engine Piper Chieftain (N931SA) with Inertial Measurement Unit (IMU) at a flying height of 600 m. Data from two GPS (Global Positioning System) ground stations were used for aircraft trajectory determination. The continuous DTM surface was created by mosaicing and then kriging 1 km2 LiDAR point cloud LAS-formated tiles using Golden Software's Surfer 8 Kriging algorithm. Horizontal accuracy and vertical accuracy is unknown. The layer is available in GEOTIF format approx. 265 MB of data. It has a UTM zone 13 projection, with a NAD83 horizonal datum and a NAVD88 vertical datum computed using NGS GEOID03 model, with FGDC-compliant metadata. A shaded relief model was also generated. A similar layer, the Digital Surface Model (DSM), is a first-stop elevation layer. A processing report and readme file are included with this data release. The DTM is available through an unrestricted public license. The LiDAR DEMs will be of interest to land managers, scientists, and others for study of topography, ecosystems, and environmental change. NOTE: This EML metadata file does not contain important geospatial data processing information. Before using any NWT LTER geospatial data read the arcgis metadata XML file in either ISO or FGDC compliant format, using ArcGIS software (ArcCatalog > description), or by viewing the .xml file provided with the geospatial dataset.

This 1m Digital Surface Model (DSM) shaded relief is derived from first-stop Light Detection and Ranging (LiDAR) point cloud data from September 2005 for the Green Lakes Valley, near Boulder Colorado. The DSM was created from LiDAR point cloud tiles subsampled to 1-meter postings, acquired by the National Center for Airborne Laser Mapping (NCALM) project. This data was collected in collaboration between the University of Colorado, Institute of Arctic and Alpine Research (INSTAAR) and NCALM, which is funded by the National Science Foundation (NSF). The DSM shaded relief has the functionality of a map layer for use in Geographic Information Systems (GIS) or remote sensing software. Total area imaged is 35 km^2. The LiDAR point cloud data was acquired with an Optech 1233 Airborne Laser Terrain Mapper (ALTM) and mounted in a twin engine Piper Chieftain (N931SA) with Inertial Measurement Unit (IMU) at a flying height of 600 m. Data from two GPS (Global Positioning System) ground stations were used for aircraft trajectory determination. The continuous DSM surface was created by mosaicing and then kriging 1 km2 LiDAR point cloud LAS-formated tiles using Golden Software's Surfer 8 Kriging algorithm. Horizontal accuracy and vertical accuracy is unknown. cm RMSE at 1 sigma. The layer is available in GEOTIF format approx. 265 MB of data. It has a UTM zone 13 projection, with a NAD83 horizonal datum and a NAVD88 vertical datum computed using NGS GEOID03 model, with FGDC-compliant metadata. This shaded relief model was also generated. A similar layer, the Digital Terrain Model (DTM), is a ground-surface elevation dataset better suited for derived layers such as slope angle, aspect, and contours. A processing report and readme file are included with this data release. The DSM dataset is available through an unrestricted public license. The LiDAR DEMs will be of interest to land managers, scientists, and others for study of topography, ecosystems, and environmental change. NOTE: This EML metadata file does not contain important geospatial data processing information. Before using any NWT LTER geospatial data read the arcgis metadata XML file in either ISO or FGDC compliant format, using ArcGIS software (ArcCatalog > description), or by viewing the .xml file provided with the geospatial dataset.

The shoreline essentially follows the 8 foot contour line, except where the ortho offered further clarification. That 8 foot contour line matches closest to what NAVD88 shows as "mean high water" (see official definition below) at 7.97 feet. MEAN HIGH WATER (MHW): "A tidal datum. The average of all the high water heights observed over the National Tidal Datum Epoch. For stations with shorter series, simultaneous observational comparisons are made with a control tide station in order to derive the equivalent datum of the National Tidal Datum Epoch." Source "The MHW line along the tidal shoreline is represented by the contour line that is 8.0' above the NAVD 88. The MHW elevation is not necessarily an equipotential (level) surface, but the variation from a level surface is not significant for this project. The determination of MHW is based on 18 yrs of tidal data and represents the latest official National Tidal Epoch of 1960-1978. The Seattle Tide Station (Sta No 944-7130) is located at the downtown ferry terminal." Source: From paper by Nick Bodnar 10/18/1993 Some other definitions regarding these shorelines (from Nick Bodnar, 10/18/1993): LAKES UNION AND WASHINGTON SHORELINE (18.6' above NAVD 88) The approximation of "ordinary high water"; the level of Lk Washington varies from 17.0'-18.6' during the year; the max lake elevation is 18.8' as controlled by Corps of Engineers (COE) at Hiram Chittenden Locks. The NAVD 88 lake elevations have been converted from the U.S. Engineers Datum. This zero of NAVD 88 is 3.25' above the Locks Datum at the common bench mark P-7. The shoreline contour of 18.8' above NAVD 88 should be used from the Locks, upstream through Lk Union and Lk Washington. The COE has performed various studies that show the level of Lk Wash to approximate an equipotential surface that can be represented by a single contour elevation for mapping purposes. OTHER LAKES The shoreline around Green Lake and all other lakes are delimited by the water/land interface as seen on the aerial photography.

Displays data from CARTO.SHORE_LN

Updated as needed.