Cross, VeeAnn A. , 2011, COMBELEV: ESRI Format Binary Grid of the Merged Bathymetry and Elevation Data from the Corsica River Estuary, Maryland For Use with USGS Cruise 07005: Open-File Report 2010-1094, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Coastal and Marine Science Center, Woods Hole, MA.This is part of the following larger work.Online Links:
- <https://pubs.usgs.gov/of/2010/1094/data/basemap/elevation.zip>
- <https://pubs.usgs.gov/of/2010/1094/html/catalog.html>
Cross, VeeAnn A. , Bratton, John F. , Worley, Charles R. , Crusius, John, and Kroeger, Kevin D. , 2011, Continuous resistivity profiling data from the Corsica River Estuary, Maryland: Open-File Report 2010-1094, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Coastal and Marine Science Center, Woods Hole, MA.Online Links:
This is a Raster data set. It contains the following raster data types:
Planar coordinates are encoded using row and column
Abscissae (x-coordinates) are specified to the nearest 30.000000
Ordinates (y-coordinates) are specified to the nearest 30.000000
Planar coordinates are specified in meters
The horizontal datum used is North American Datum of 1983.
The ellipsoid used is Geodetic Reference System 80.
The semi-major axis of the ellipsoid used is 6378137.000000.
The flattening of the ellipsoid used is 1/298.257222.
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The purpose of this dataset is to provide a seamless elevation/bathymetry grid as a basemap layer for the work in the Corsica River Estuary.
U.S. Geological Survey (USGS), EROS Data Center, 1999, National Elevation Dataset: U.S. Geological Survey, Sioux Falls, SD.Online Links:
NOAA Coastal Services Center Coastal Remote Sensing Program, 20070613, 2003 Maryland LIDAR mapping project.Online Links:
Department of Commerce (DOC), National Oceanic and Atmospheric Adminis, 1998, Chesapeake Bay, VA/MD (M130) Bathymetric Digital Elevation Model (30 meter resolution) Derived From Source Hydrographic Survey Soundings Collected by NOAA: NOAA's Ocean Service, Special Projects (SP), Silver Spring, MD.Online Links:
Person who carried out this activity:
(508) 548-8700 x2251 (voice)
(508) 457-2310 (FAX)
vatnipp@usgs.gov
Data sources used in this process:
Data sources produced in this process:
Data sources used in this process:
Data sources produced in this process:
Data sources used in this process:
Data sources produced in this process:
Data sources used in this process:
Data sources produced in this process:
NED_UTM18 = project(ned_37057094, geog2utm, bilinear).Effectively what this does is project ned_37057094 using the parameters supplied in the file geog2utm using a bilinear interpolation method. The contents of geog2utm are as follows:
INPUT PROJECTION GEOGRAPHIC UNITS DD DATUM NAD83 PARAMETERS OUTPUT PROJECTION UTM UNITS METERS ZONE 18 DATUM NAD83 PARAMETERSEND
Data sources used in this process:
Data sources produced in this process:
Data sources used in this process:
Data sources produced in this process:
Department of Commerce (DOC), National Oceanic and Atmospheric Adminis, 1998, Chesapeake Bay, VA/MD (M130) Bathymetric Digital Elevation Model (30 meter resolution) Derived From Source Hydrographic Survey Soundings Collected by NOAA: NOAA's Ocean Service, Special Projects (SP), Silver Spring, MD.Online Links:
U.S. Geological Survey (USGS), EROS Data Center, 1999, National Elevation Dataset: U.S. Geological Survey, Sioux Falls, SD.Online Links:
NOAA Coastal Services Center Coastal Remote Sensing Program, 20070613, 2003 Maryland LIDAR mapping project.Online Links:
This grid is a combination of three different datasets with three different horizontal accuracies. For the LIDAR data, the metadata reports the horizontal accuracy as "The horizontal coordinate values were designed to meet NSSDA accuracy for data at 1:2400 scale." The metadata for the NED elevation data does not specify a horizontal accuracy. The Chesapeake Estuarine bathymetry dataset metadata reports the horizontal accuracy as "The horizontal accuracy of the DEM is expressed as an estimated root mean square error (RMSE). The estimate of the RMSE is based upon horizontal accuracy tests of the source soundings used to generate the DEM. As a first approximation the locational accuracy of the source soundings are 0.0015 m at source "Smooth Sheet" scale (120 m @ 1:80,000 to 15 m @ 1:10,000). Smooth Sheets are maps generated as a principle product of each (historic) hydrographic survey with fully corrected soundings plotted on them. Digital elevation models comply with the National Map Accuracy Standards (NMAS) accuracy requirements. The positional accuracy is estimated at 3 meters."
This grid is a combination of three different datasets with three different vertical accuracies. For the LIDAR data, the metadata reports the vertical accuracy as "The RMSE value of 14.3 cm at the 95% confidence level was determined by an independent accuracy assessment conducted by Dewberry LLC according to the contract specifications. These specifications followed FEMA Appendix A guidelines regarding assessing vertical accuracy. For data accurate to within 18.5 cm RMSE, the guidelines recommended a minimum of 20 independent check points be located in each of 5 different land cover categories: Grass/Ground, High Grass/Crops, Brush/Low Trees, Forest, and Urban/Pavement. A total of 125 points were used for the assessments. These points were surveyed by a licensed land surveyor and provided a positional location and elevation with an accuracy that exceeded the predicted accuracy of the LIDAR data. The entire accuracy reports can be found at <http://dnrweb.dnr.state.md.us/gis/data/lidar>. The RMSE value is 14.3 cm. See the Vertical Positional Accuracy Report section for more information."
The metadata for the NED elevation data does not specify a vertical accuracy.
The Chesapeake Estuarine bathymetry dataset metadata reports the vertical accuracy as "The vertical RMSE statistic is used to describe the vertical accuracy of a DEM. It encompasses both random and systematic errors introduced during production of the data. The RMSE is encoded in element number 5 of record C of the DEM. This accuracy estimate includes components related to quantization of the source soundings (1.3 to 0.15 m), the systematic editing of the source data (1percentor 0.10m), un-sampled bathymetric features (estimated at less than 5percentof depth), time related changes (erosion, deposition, and seismic shifts), and dredging operations (cut and fill).
It is estimated that the accuracy of the Bathymetric DEMs is 2 percent of depth or 1 meter for depths grater than 20 meters and 2 percent of depth or 0.20 meters for depths shallower than 20 meters. THESE DEMs SHOULD NOT BE USED FOR NAVIGATION.
There are three types of DEM vertical errors: blunder, systematic, and random. These errors are reduced in magnitude by editing but cannot be completely eliminated. Blunders are errors of major proportions and are easily identified and removed during interactive editing. Systematic errors follow some fixed pattern and are introduced by data collection procedures and systems. Systematic error artifacts include vertical unsampled elevation shifts, relative spacing of the source soundings, misinterpretation of terrain surface caused by softness or poor reflectivity and by the resolution of the collected soundings (feet, feet and fractions, fathoms, fathoms and fractions, meters, tenths of meters etc.). Random errors result from unknown or accidental causes. The 1 degree (DSQ) DEMs are generated from 30 m grids on UTM projection. The RMSE difference between these surfaces is an estimate of the vertical accuracy of the DSQ DEMs."
By combining the three individual datasets, a complete elevation surface for the study area was derived.
The focus of this dataset is the bathymetry, so that dataset was given priority when combining the datasets. The individual datasets were not checked for errors prior to combining the datasets. Both land elevation datasets (NED and the LIDAR) use the same vertical datum - NAVD88. The bathymetry dataset metadata specified the vertical coordinate system as being referenced to the local tidal datum at the time of the hydrographic survey. These surveys ranged from 1859 to 1993 in the Chesapeake Bay area. No attempt was made to adjust between the two vertical datums represented by these 3 datasets.
Are there legal restrictions on access or use of the data?
- Access_Constraints: None.
- Use_Constraints:
- The public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. Please recognize the U.S. Geological Survey and the National Oceanic and Atmospheric Administration (NOAA) National Ocean Service (NOS) as the originators of the individual datasets. These data are not to be used for navigation.
(508) 548-8700 x2251 (voice)
(508) 457-2310 (FAX)
vatnipp@usgs.gov
Downloadable Data
Neither the U.S. government, the Department of the Interior, nor the USGS, nor any of their employees, contractors, or subcontractors, make any warranty, express or implied, nor assume any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, nor represent that its use would not infringe on privately owned rights. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of these data or related materials. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
| Data format: | The WinZip files contains the ESRI binary grid as well as the associated metadata files. in format WinZip (version 9.0) Size: 0.383 MB |
|---|---|
| Network links: |
<https://pubs.usgs.gov/of/2010/1094/html/catalog.html> <https://pubs.usgs.gov/of/2010/1094/data/basemap/elevation.zip> |
| Media you can order: |
DVD-ROM
(Density 4.75
GBytes)
(format UDF)
|
The data are provided in a WinZip compressed file. The user must have software capable of uncompressing the archive. Additionally, once uncompressed the data are in the ESRI binary grid format. The user must have software capable of displaying this data format. The binary grid is actually made up of two folders, an info folder and the folder with the grid name. Both folders, and their relative path structure are necessary to fully utilize the data.
(508) 548-8700 x2251 (voice)
(508) 457-2310 (FAX)
vatnipp@usgs.gov
