Esri Format Binary Grid of the Merged Bathymetry and Elevation Data from the Corsica River Estuary, Maryland For Use with USGS Cruise 07005 (COMBELEV)

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Frequently anticipated questions:


What does this data set describe?

Title:
Esri Format Binary Grid of the Merged Bathymetry and Elevation Data from the Corsica River Estuary, Maryland For Use with USGS Cruise 07005 (COMBELEV)
Abstract:
Submarine groundwater discharge (SGD) into Maryland's Corsica River Estuary was investigated as part of a larger study to determine the importance of nutrient delivery to Chesapeake Bay via this pathway. Resource managers are concerned about nutrients that are entering the estuary via submarine groundwater discharge from this primarily agricultural watershed that may be contributing to eutrophication, harmful algal blooms, and fish kills. An interdisciplinary U.S. Geological Survey (USGS) science team conducted field operations in the estuary in April and May 2007. Techniques used included continuous resistivity profiling (CRP), piezometer sampling, seepage meter measurements, and collection of a radon tracer time series. Better understanding of the style, locations, and rates of groundwater discharge could lead to improved models and mitigation strategies for estuarine nutrient over-enrichment in the Corsica River Estuary, and other similar settings. More information on the field work can be accessed from the Woods Hole Coastal and Marine Science Center Field Activity webpage: https://cmgds.marine.usgs.gov/fan_info.php?fan=2007-005-FA.
  1. How might this data set be cited?
    Cross, VeeAnn A., 2011, Esri Format Binary Grid of the Merged Bathymetry and Elevation Data from the Corsica River Estuary, Maryland For Use with USGS Cruise 07005 (COMBELEV): 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 part of the following larger work.

    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, Reston, VA.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -76.160718
    East_Bounding_Coordinate: -76.060537
    North_Bounding_Coordinate: 39.121622
    South_Bounding_Coordinate: 39.034459
  3. What does it look like?
    https://pubs.usgs.gov/of/2010/1094/data/basemap/elevation/combelev.gif (GIF)
    Thumbnail image of the color-coded relief in the Corsica River Estuary area.
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 2011
    Currentness_Reference:
    publication date
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: raster digital data
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a Raster data set. It contains the following raster data types:
      • Dimensions 319 x 285 x 1, type Grid Cell
    2. What coordinate system is used to represent geographic features?
      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 18
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.999600
      Longitude_of_Central_Meridian: -75.000000
      Latitude_of_Projection_Origin: 0.000000
      False_Easting: 500000.000000
      False_Northing: 0.000000
      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.
      Vertical_Coordinate_System_Definition:
      Altitude_System_Definition:
      Altitude_Datum_Name: North American Vertical Datum of 1988
      Altitude_Resolution: 0.1
      Altitude_Distance_Units: meters
      Altitude_Encoding_Method:
      Explicit elevation coordinate included with horizontal coordinates
      Depth_System_Definition:
      Depth_Datum_Name:
      referenced to local tidal datum at the time of the hydrogaphic survey
      Depth_Resolution: 0.1
      Depth_Distance_Units: meters
      Depth_Encoding_Method: Explicit depth coordinate included with horizontal coordinates
  7. How does the data set describe geographic features?

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • VeeAnn A. Cross
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    VeeAnn A. Cross
    U.S. Geological Survey
    Marine Geologist
    Woods Hole Coastal and Marine Science Center
    Woods Hole, MA

    (508) 548-8700 x2251 (voice)
    (508) 457-2310 (FAX)
    vatnipp@usgs.gov

Why was the data set created?

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.

How was the data set created?

  1. From what previous works were the data drawn?
    NED (source 1 of 3)
    U.S. Geological Survey (USGS), EROS Data Center, 1999, National Elevation Dataset: U.S. Geological Survey, Sioux Falls, SD.

    Online Links:

    Type_of_Source_Media: online
    Source_Contribution: This dataset provided the bulk of the on land elevation data.
    LIDAR (source 2 of 3)
    NOAA Coastal Services Center Coastal Remote Sensing Program, 20070613, 2003 Maryland LIDAR mapping project.

    Online Links:

    Type_of_Source_Media: online
    Source_Contribution:
    The LIDAR data provided the higher resolution land data and helped bridge the small gap between the NED elevation data and the bathymetry data.
    bathy (source 3 of 3)
    Department of Commerce (DOC), National Oceanic and Atmospheric Administration (NOAA), National Ocean Service (NOS), Special Projects (SP), 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:

    Type_of_Source_Media: online
    Source_Contribution:
    This dataset provided all the bathymetric data in the study area.
  2. How were the data generated, processed, and modified?
    Date: May-2007 (process 1 of 11)
    The NED was downloaded in an ESRI binary grid format in a WinZip file. Once extracted, the grid ned_37057094 was created. These original grids are in a geographic coordinate system, NAD83, with a vertical datum of NAVD88. The cell size of these grids is 0.000278 decimal degrees. These files cover the land portion of the area of interest. The cell values where water occurs is usually set to 0 - not true elevation (bathymetry) values. This process step and all subsequent process steps were carried out by the same person - VeeAnn A. Cross. Person who carried out this activity:
    VeeAnn A. Cross
    U.S. Geological Survey
    Marine Geologist
    Woods Hole Coastal and Marine Science Center
    Woods Hole, MA

    (508) 548-8700 x2251 (voice)
    (508) 457-2310 (FAX)
    vatnipp@usgs.gov
    Data sources produced in this process:
    • ned_37057094
    Date: Jun-2007 (process 2 of 11)
    The LIDAR was downloaded as a binary floating-point raster dataset. This data file was converted to an ESRI binary grid format using ArcMap 9.1 - ArcToolbox - Conversion Tools - To Raster - Float to Raster. The input dataset was vatnipp17193.flt with the output grid named FloatTo_vatn1. Additionally, the resulting grid needed the projection defined. Based on the metadata, the projection is Geographic, NAD83. This definition was accomplished in ArcMap 9.1 - ArcToolbox - Data Management Tools - Projections and Transformations - Define Projection. The input dataset was FloatTo_vatn1 and the coordinate system chose was GCS_North_American_1983. Data sources used in this process:
    • vatnipp17193.flt
    Data sources produced in this process:
    • FloatTo_vatn1
    Date: Aug-2006 (process 3 of 11)
    The Chesapeake Estuarine bathymetry dataset was downloaded in DEM format. Chesapeake Bay actually required 3 separate DEM's. For the Corsica River Estuary the northernmost of those DEM's covered the area of interest. This file was M130_39076C2_BIG3.dem. The original projection of the data is UTM, Zone 18, NAD27 with a cell size of 30 meters. The vertical datum for the bathymetry is referenced to local tidal datum at the time of the hydrographic surveys that make up the dataset. The vertical unit is meters. The Digital Elevation Model (DEM) estuarine files needed to be converted from the USGS DEM format to ESRI grid format. To do that, ArcMap 9.0 - ArcToolbox - Conversion Tools - To Raster - DEM to Raster. The output data type is float, with the Z-factor left to the default value of 1. Data sources used in this process:
    • M130_39076C2_BIG3.dem
    Data sources produced in this process:
    • big3
    Date: 2006 (process 4 of 11)
    The estuarine bathymetry grids then needed to be projected to UTM, Zone 18, NAD83 - basically just a datum transformation. To do this, ArcMap 9.0 - Data Management Tools - Projections and Transformations - Raster - Project Raster. The geographic transformation used was NAD_1927_to NAD_1980_NADCON. The resampling method was bilinear. Data sources used in this process:
    • big3
    Data sources produced in this process:
    • big3_nad83
    Date: Nov-2009 (process 5 of 11)
    The LIDAR grid data was projected from Geographic, NAD83 to UTM, Zone 18, NAD83. This was accomplished with ArcMap 9.2 - ArcToolbox - Data Management Tools - Projections and Transformations - Raster - Project Raster. Parameters as follows: input raster: floatto_vatn1; input coordinate system - GCS_North_American_1983; output raster: csc_utm18; output coordinate system: NAD_1983_UTM_Zone_18N; resampling technique: bilinear. Remainder of the parameters were left to the default. No transformation was necessary. Data sources used in this process:
    • floatto_vatn1
    Data sources produced in this process:
    • csc_utm18
    Date: May-2007 (process 6 of 11)
    The NED elevation dataset was projected from the geographic, NAD83 to UTM, Zone 18, NAD83. This was accomplished from ArcInfo command line of ArcGIS 9.1. The command line used to do this was:
    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
    PARAMETERS
    
    END Data sources used in this process:
    • ned_37057094
    Data sources produced in this process:
    • NED_UTM18
    Date: Nov-2009 (process 7 of 11)
    With all the individual datasets in ESRI binary grid format, projection UTM, NAD83, I want to combine the datasets. I do this using raster calculator in ArcMap 9.2 using the following command: merge([big3_nad83], [csc_utm18], [ned_utm18]) Using raster calculator and the merge command, the order of the grids listed is important. The first grid listed has highest priority and will overwrite any values in the same location from the other grids. The second grid listed will overwrite any values in the same location of any grid that comes after it in the list. So in this case, the estuarine bathymetry dataset was assigned priority 1, the LIDAR data priority 2, and to fill in any remaining gaps, the NED data were used. This creates a temporary raster dataset. Then within the table of contents in ArcMap, I right mouse click and select Data - Make Permanent. The resulting output grid is combelev. Data sources used in this process:
    • big3_nad83
    • csc_utm18
    • ned_utm18
    Data sources produced in this process:
    • combelev
    Date: 16-Oct-2017 (process 8 of 11)
    Edits to the metadata were made to fix any errors that MP v 2.9.36 flagged. This is necessary to enable the metadata to be successfully harvested for various data catalogs. In some cases, this meant adding text "Information unavailable" or "Information unavailable from original metadata" for those required fields that were left blank. Other minor edits were probably performed (title, publisher, publication place, etc.). Attempted to modify http to https where appropriate. Reordered the links in the identification section to have a landing page link as the first link. Updated the link to the field activity. The distribution format name was modified in an attempt to be more consistent with other metadata files of the same data format. The metadata date (but not the metadata creator) was edited to reflect the date of these changes. The metadata available from a harvester may supersede metadata bundled within a download file. Compare the metadata dates to determine which metadata file is most recent. Person who carried out this activity:
    U.S. Geological Survey
    Attn: VeeAnn A. Cross
    Marine Geologist
    384 Woods Hole Road
    Woods Hole, MA

    508-548-8700 x2251 (voice)
    508-457-2310 (FAX)
    vatnipp@usgs.gov
    Date: 20-Jul-2018 (process 9 of 11)
    USGS Thesaurus keywords added to the keyword section. Person who carried out this activity:
    U.S. Geological Survey
    Attn: VeeAnn A. Cross
    Marine Geologist
    384 Woods Hole Road
    Woods Hole, MA

    508-548-8700 x2251 (voice)
    508-457-2310 (FAX)
    vatnipp@usgs.gov
    Date: 18-Nov-2019 (process 10 of 11)
    Crossref DOI link was added as the first link in the metadata. Person who carried out this activity:
    U.S. Geological Survey
    Attn: VeeAnn A. Cross
    Marine Geologist
    384 Woods Hole Road
    Woods Hole, MA

    508-548-8700 x2251 (voice)
    508-457-2310 (FAX)
    vatnipp@usgs.gov
    Date: 08-Sep-2020 (process 11 of 11)
    Added keywords section with USGS persistent identifier as theme keyword. Person who carried out this activity:
    U.S. Geological Survey
    Attn: VeeAnn A. Cross
    Marine Geologist
    384 Woods Hole Road
    Woods Hole, MA

    508-548-8700 x2251 (voice)
    508-457-2310 (FAX)
    vatnipp@usgs.gov
  3. What similar or related data should the user be aware of?
    Department of Commerce (DOC), National Oceanic and Atmospheric Administration (NOAA), National Ocean Service (NOS), Special Projects (SP), 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:

    Other_Citation_Details: Time period of content is 20030301 to 20031130

How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?
  2. How accurate are the geographic locations?
    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."
  3. How accurate are the heights or depths?
    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."
  4. Where are the gaps in the data? What is missing?
    By combining the three individual datasets, a complete elevation surface for the study area was derived.
  5. How consistent are the relationships among the observations, including topology?
    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.

How can someone get a copy of the data set?

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.
  1. Who distributes the data set? (Distributor 1 of 1)
    VeeAnn A. Cross
    U.S. Geological Survey
    Marine Geologist
    Woods Hole Coastal and Marine Science Center
    Woods Hole, MA

    (508) 548-8700 x2251 (voice)
    (508) 457-2310 (FAX)
    vatnipp@usgs.gov
  2. What's the catalog number I need to order this data set? Downloadable Data
  3. What legal disclaimers am I supposed to read?
    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.
  4. How can I download or order the data?
  5. What hardware or software do I need in order to use the data set?
    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.

Who wrote the metadata?

Dates:
Last modified: 08-Sep-2020
Metadata author:
VeeAnn A. Cross
U.S. Geological Survey
Marine Geologist
Woods Hole Coastal and Marine Science Center
Woods Hole, MA

(508) 548-8700 x2251 (voice)
(508) 457-2310 (FAX)
vatnipp@usgs.gov
Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)

This page is <https://cmgds.marine.usgs.gov/catalog/whcmsc/open_file_report/ofr2010-1094/combelevmeta.faq.html>
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