NTHMP DEM Project
Entry ID:
gov.noaa.ngdc.mgg.dem.nthmp
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Summary
Abstract:
ABSTRACT: NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) to support individual coastal States as part of the National Tsunami Hazard Mitigation Program's (NTHMP) efforts to improve community preparedness and hazard mitigation. These integrated bathymetric-topographic DEMs are used to support tsunami and coastal inundation mapping. ... 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 various vertical and horizontal datums depending on the specific modeling requirements of each State. For specific datum information on each DEM, refer to the appropriate DEM documentation. Cell sizes also vary depending on the specification required by modelers in each State, but typically range from 8/15 arc-second (~16 meters) to 8 arc-seconds (~240 meters).
CURRENTNESS REFERENCE: ground condition
NATIVE: ESRI ArcCatalog 9.2.4.1420 
Purpose:
PURPOSE: Developed for the National Tsunami Hazard Mitigation Program to support tsunami modeling and coastal inundation mapping efforts.
Related URL
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Description:
Web page for searching and downloading DEMs
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Geographic Coverage
(Click for Interactive Map)
Spatial coordinates
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N: 62.0
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S: 32.0
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E: -116.0
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W: -180.0
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Data Set Citation
Dataset Originator/Creator:
DOC/NOAA/NESDIS/NGDC > National Geophysical Data Center, NESDIS, NOAA, U.S. Department of Commerce (comp)NTHMP > National Tsunami Hazard Mitigation Program
Dataset Title:
NTHMP DEM Project
Dataset Series Name:
NTHMP DEMs
Dataset Release Date:
2009-04-20
Dataset Release Place:
Boulder, Colorado
Dataset Publisher:
DOC/NOAA/NESDIS/NGDC > National Geophysical Data Center, NESDIS, NOAA, U.S. Department of Commerce
Issue Identification:
Project metadata record
Online Resource:
http://www.ngdc.noaa.gov/mgg/inundation/nthmp/nthmp.html
Quality
LOGICAL CONSISTENCY REPORT: Datasets are visually compared internally and externally (with other overlapping datasets. satellite images, and maps) in ESRI ArcGIS for identification of anomalous elevations or data inconsistencies. Where elevation inconsistencies occurred, the most recent and/or highest resolution data set is selected for use in that region. Elevations in the older and/or ... lower-resolution datasets are deleted prior to building the DEMs.
COMPLETENESS REPORT: NGDC makes every effort to obtain all available digital topographic and bathymetric datasets in each region for use in building the DEMs.
HORIZONTAL POSITIONAL ACCURACY REPORT: The horizontal accuracy of bathymetric and topographic features in the DEMs are dependent upon the accuracy of the input datasets used to determine corresponding cell values.
VERTICAL POSITIONAL ACCURACY REPORT: The vertical accuracy of bathymetric and topographic features in the DEM is dependent upon the accuracy of the input datasets used to determine corresponding cell values. Gridding interpolation to determine values between sparse NOS hydrographic soundings in deep-water degrades the vertical accuracy of deep-water elevations.
LINEAGE/PROCESS STEP:
PROCESS DESCRIPTION: All datasets obtained by NGDC are converted to common horizontal and vertical datums based on the States' requirements using FME. They are also converted to common file format, ESRI point shapefiles, for visualization and inspection.
LINEAGE/PROCESS STEP:
PROCESS DESCRIPTION: Datasets are visually inspected with ArcGIS for identification and editing of data anomalies. Datasets are then compared with overlapping datasets to ensure data consistency.
LINEAGE/PROCESS STEP:
PROCESS DESCRIPTION: xyz files of the bathymetric data are surfaced using GMT's 'surface' tool onto an 8 arc-second grid that is interpolated to fill empty cells. Points extracted every 10 meters along the coastline are also included to ensure that the bathymetric grid reaches zero at the coast. The resulting Arc ASCII grid is imported into ArcGIS and clipped to the coastline to remove values over land.
LINEAGE/PROCESS STEP:
PROCESS DESCRIPTION: xyz files for each input dataset are gridded using MB-System's 'mbgrid' tool, which utilizes a high-tension spline interpolation method to fill grid cells with no input elevation values. Preferential weighting is given to more recent, higher-accuracy datasets. Gridding is typically performed in quadrants, each with a 5% data buffer. The grids are imported in ArcGIS and seamlessly merged to create the final DEM.
LINEAGE/PROCESS STEP:
PROCESS DESCRIPTION: The DEMs are quantitatively evaluated by comparing with source datasets. They are visually evaluated by converting to UTM-zone coordinates (units of meters horizontally and vertically) and then creating a slope grid to identify gridding artifacts in the DEMs.
PROCESS DATE: 20090420
PROCESS DATE: 20081031
PROCESS DATE: 20081031
PROCESS DATE: 20090420
PROCESS DATE: 20090420
Access Constraints
ACCESS CONSTRAINTS: None
DISTRIBUTION LIABILITY: While every effort has been made to ensure that these data are accurate and reliable within the limits of the current state of the art, NOAA cannot assume liability for any damages caused by any errors or omissions in the data, nor as a result of the failure of the data to function on a particular system. NOAA makes no warranty, expressed or implied, nor does the fact of distribution constitute such a warranty.
CUSTOM ORDER PROCESS: Contact the data center
Use Constraints
None
Data Set Progress
IN WORK
Distribution
Distribution Size:
400000000
Distribution Format:
netCDF 1
Fees:
None
Personnel
Role:
TECHNICAL CONTACT
Role:
DIF AUTHOR
Phone:
303-497-6505
Fax:
303-497-6513
Email:
Barry.Eakins at noaa.gov
Contact Address:
NOAA/NESDIS/NGDC
325 Broadway, E/GC3
City:
Boulder
Province or State:
Colorado
Postal Code:
80305-3328
Country:
USA
Creation and Review Dates
DIF Creation Date:
2010-05-28
Last DIF Revision Date:
2011-12-29
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