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.
By combining the three individual datasets, a complete elevation surface for the study area was derived.
Source_Information:
Source_Citation:
Citation_Information:
Originator: U.S. Geological Survey (USGS), EROS Data Center
Publication_Date: 1999
Title: National Elevation Dataset
Geospatial_Data_Presentation_Form: raster digital data
Publication_Information:
Publication_Place: Sioux Falls, SD
Publisher: U.S. Geological Survey
Online_Linkage: http://ned.usgs.gov/
Online_Linkage: http://seamless.usgs.gov/
Type_of_Source_Media: online
Source_Time_Period_of_Content:
Time_Period_Information:
Single_Date/Time:
Calendar_Date: 1999
Source_Currentness_Reference: publication date
Source_Citation_Abbreviation: NED
Source_Contribution: This dataset provided the bulk of the on land elevation data.
Source_Information:
Source_Citation:
Type_of_Source_Media: online
Source_Time_Period_of_Content:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date: 20030301
Ending_Date: 20031130
Source_Currentness_Reference: ground condition
Source_Citation_Abbreviation: LIDAR
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.
Source_Information:
Source_Citation:
Citation_Information:
Originator:
Department of Commerce (DOC), National Oceanic and Atmospheric Administration (NOAA), National Ocean Service (NOS), Special Projects (SP)
Publication_Date: 1998
Title:
Chesapeake Bay, VA/MD (M130) Bathymetric Digital Elevation Model (30 meter resolution) Derived From Source Hydrographic Survey Soundings Collected by NOAA
Geospatial_Data_Presentation_Form: raster digital data
Publication_Information:
Publication_Place: Silver Spring, MD
Publisher: NOAA's Ocean Service, Special Projects (SP)
Online_Linkage: http://estuarinebathymetry.noaa.gov/
Type_of_Source_Media: online
Source_Time_Period_of_Content:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date: 1859
Ending_Date: 1993
Source_Currentness_Reference: ground condition
Source_Citation_Abbreviation: bathy
Source_Contribution:
This dataset provided all the bathymetric data in the study area.
Process_Step:
Process_Description:
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.
Process_Date: 200705
Source_Produced_Citation_Abbreviation: ned_37057094
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: VeeAnn A. Cross
Contact_Organization: U.S. Geological Survey
Contact_Position: Marine Geologist
Contact_Address:
Address_Type: mailing and physical address
Address: Woods Hole Coastal and Marine Science Center
Address: 384 Woods Hole Rd.
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543-1598
Contact_Voice_Telephone: (508) 548-8700 x2251
Contact_Facsimile_Telephone: (508) 457-2310
Contact_Electronic_Mail_Address: vatnipp@usgs.gov
Process_Step:
Process_Description:
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.
Source_Used_Citation_Abbreviation: vatnipp17193.flt
Process_Date: 200706
Source_Produced_Citation_Abbreviation: FloatTo_vatn1
Process_Step:
Process_Description:
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.
Source_Used_Citation_Abbreviation: M130_39076C2_BIG3.dem
Process_Date: 200608
Source_Produced_Citation_Abbreviation: big3
Process_Step:
Process_Description:
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.
Source_Used_Citation_Abbreviation: big3
Process_Date: 2006
Source_Produced_Citation_Abbreviation: big3_nad83
Process_Step:
Process_Description:
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.
Source_Used_Citation_Abbreviation: floatto_vatn1
Process_Date: 200911
Source_Produced_Citation_Abbreviation: csc_utm18
Process_Step:
Process_Description:
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
Source_Used_Citation_Abbreviation: ned_37057094
Process_Date: 200705
Source_Produced_Citation_Abbreviation: NED_UTM18
Process_Step:
Process_Description:
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.
Source_Used_Citation_Abbreviation: big3_nad83
Source_Used_Citation_Abbreviation: csc_utm18
Source_Used_Citation_Abbreviation: ned_utm18
Process_Date: 200911
Source_Produced_Citation_Abbreviation: combelev
Process_Step:
Process_Description:
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.
Process_Date: 20171016
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: U.S. Geological Survey
Contact_Person: VeeAnn A. Cross
Contact_Position: Marine Geologist
Contact_Address:
Address_Type: Mailing and Physical
Address: 384 Woods Hole Road
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543-1598
Contact_Voice_Telephone: 508-548-8700 x2251
Contact_Facsimile_Telephone: 508-457-2310
Contact_Electronic_Mail_Address: vatnipp@usgs.gov
Process_Step:
Process_Description: USGS Thesaurus keywords added to the keyword section.
Process_Date: 20180720
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: U.S. Geological Survey
Contact_Person: VeeAnn A. Cross
Contact_Position: Marine Geologist
Contact_Address:
Address_Type: Mailing and Physical
Address: 384 Woods Hole Road
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543-1598
Contact_Voice_Telephone: 508-548-8700 x2251
Contact_Facsimile_Telephone: 508-457-2310
Contact_Electronic_Mail_Address: vatnipp@usgs.gov
Process_Step:
Process_Description: Crossref DOI link was added as the first link in the metadata.
Process_Date: 20191118
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: U.S. Geological Survey
Contact_Person: VeeAnn A. Cross
Contact_Position: Marine Geologist
Contact_Address:
Address_Type: Mailing and Physical
Address: 384 Woods Hole Road
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543-1598
Contact_Voice_Telephone: 508-548-8700 x2251
Contact_Facsimile_Telephone: 508-457-2310
Contact_Electronic_Mail_Address: vatnipp@usgs.gov
Process_Step:
Process_Description:
Added keywords section with USGS persistent identifier as theme keyword.
Process_Date: 20200908
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: U.S. Geological Survey
Contact_Person: VeeAnn A. Cross
Contact_Position: Marine Geologist
Contact_Address:
Address_Type: Mailing and Physical
Address: 384 Woods Hole Road
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543-1598
Contact_Voice_Telephone: 508-548-8700 x2251
Contact_Facsimile_Telephone: 508-457-2310
Contact_Electronic_Mail_Address: vatnipp@usgs.gov