Metadata: Identification_Information: Citation: Citation_Information: Originator: David C. Twichell Originator: VeeAnn A. Cross Publication_Date: 2003 Title: Unenhanced TIFF Sidescan-Sonar Mosaic of Boulder Basin - Lake Mead, Nevada: Geographic Coordinates (BBASIN_UNGEOG.TIF) Edition: 1.0 Geospatial_Data_Presentation_Form: remote-sensing image Series_Information: Series_Name: Open-File Report Issue_Identification: 03-320 Publication_Information: Publication_Place: Woods Hole Coastal and Marine Science Center, Woods Hole, MA Publisher: U.S. Geological Survey, Coastal and Marine Geology Program Online_Linkage: https://doi.org/10.3133/ofr03320 Online_Linkage: http://pubs.usgs.gov/of/2003/of03-320/data/sscanimgs/geographic/unenhanced/bbasin_ungeog.tif Online_Linkage: http://pubs.usgs.gov/of/2003/of03-320/data/sscanimgs/geographic/unenhanced/bbasin_ungeog.tfw Online_Linkage: http://pubs.usgs.gov/of/2003/of03-320/htmldocs/datacatalog.htm#sscan Larger_Work_Citation: Citation_Information: Originator: David C. Twichell Originator: VeeAnn A. Cross Originator: Stephen D. Belew Publication_Date: 2003 Title: Mapping the floor of Lake Mead (Nevada and Arizona): Preliminary discussion and GIS data release Edition: 1.0 Series_Information: Series_Name: Open-File Report Issue_Identification: 03-320 Publication_Information: Publication_Place: Reston, VA Publisher: U.S. Geological Survey Online_Linkage: http://pubs.usgs.gov/of/2003/of03-320/ Description: Abstract: Lake Mead is a large interstate reservoir located in the Mojave Desert of southeastern Nevada and northwestern Arizona. It was impounded in 1935 by the construction of Hoover Dam and is one of a series of multi-purpose reservoirs on the Colorado River. The lake extends 183 km from the mouth of the Grand Canyon to Black Canyon, the site of Hoover Dam, and provides water for residential, commercial, industrial, recreational, and other non-agricultural users in communities across the southwestern United States. Extensive research has been conducted on Lake Mead, but a majority of the studies have involved determining levels of anthropogenic contaminants such as synthetic organic compounds, heavy metals and dissolved ions, furans/dioxins, and nutrient loading in lake water, sediment, and biota (Preissler, et al., 1998; Bevans et al, 1996; Bevans et al., 1998; Covay and Leiker, 1998; LaBounty and Horn, 1997; Paulson, 1981). By contrast, little work has focused on the sediments in the lake and the processes of deposition (Gould, 1951). To address these questions, sidescan-sonar imagery and high-resolution seismic-reflection profiles were collected throughout Lake Mead by the USGS in cooperation with researchers from University of Nevada Las Vegas (UNLV). These data allow a detailed mapping of the surficial geology and the distribution and thickness of sediment that has accumulated in the lake since the completion of Hoover Dam. Results indicate that the accumulation of post-impoundment sediment is primarily restricted to former river and stream beds that are now submerged below the lake while the margins of the lake appear to be devoid of post-impoundment sediment. The sediment cover along the original Colorado River bed is continuous and is typically greater than 10 m thick through much of its length. Sediment thickness in some areas exceeds 35 m while the smaller tributary valleys typically are filled with less than 4 m of sediment. Away from the river beds that are now covered with post-impoundment sediment, pre-impoundment alluvial deposits and rock outcrops are still exposed on the lake floor. Purpose: This sidescan-sonar imagery is used to map the morphology of the lake floor and determine the extent of sediment distribution on the lake floor. Time_Period_of_Content: Time_Period_Information: Range_of_Dates/Times: Beginning_Date: 19990514 Ending_Date: 19990525 Currentness_Reference: ground condition Status: Progress: Complete Maintenance_and_Update_Frequency: None planned Spatial_Domain: Bounding_Coordinates: West_Bounding_Coordinate: -114.865290 East_Bounding_Coordinate: -114.628145 North_Bounding_Coordinate: 36.155755 South_Bounding_Coordinate: 36.007249 Keywords: Theme: Theme_Keyword_Thesaurus: USGS Metadata Identifier Theme_Keyword: USGS:7d62487e-0e4a-4bf9-8566-2f2753a905b3 Theme: Theme_Keyword_Thesaurus: None Theme_Keyword: CMGP Theme_Keyword: Coastal and Marine Geology Program Theme_Keyword: images Theme_Keyword: mosaic Theme_Keyword: OFR03-320 Theme_Keyword: Open-File Report Theme_Keyword: reservoir Theme_Keyword: sidescan Theme_Keyword: sidescan sonar Theme_Keyword: GeoTIFF Theme_Keyword: U.S. Geological Survey Theme_Keyword: USGS Theme_Keyword: Woods Hole Science Center Theme_Keyword: WHSC Theme: Theme_Keyword_Thesaurus: ISO 19115 Topic Category Theme_Keyword: inlandWaters Theme_Keyword: imageryBaseMapsEarthCover Theme_Keyword: geoscientificInformation Theme: Theme_Keyword_Thesaurus: USGS Thesaurus Theme_Keyword: lakebed acoustic reflectivity Theme_Keyword: image mosaics Theme_Keyword: sidescan sonar Theme_Keyword: geophysics Theme_Keyword: geospatial datasets Place: Place_Keyword_Thesaurus: None Place_Keyword: Arizona Place_Keyword: Boulder Basin Place_Keyword: Colorado River Place_Keyword: Hoover Dam Place_Keyword: Lake Mead Place_Keyword: Las Vegas Place_Keyword: Mojave Desert Place_Keyword: Nevada Place_Keyword: United States Place_Keyword: North America Access_Constraints: NONE Use_Constraints: The U.S. Geological Survey must be referenced as the originator of the dataset in any future products or research derived from these data. Public domain data from the U.S. government is freely redistributable with proper metadata and source attribution. Point_of_Contact: Contact_Information: Contact_Person_Primary: Contact_Person: David C. Twichell Contact_Organization: U.S. Geological Survey Contact_Position: Oceanographer Contact_Address: Address_Type: mailing and physical address Address: 384 Woods Hole Rd. City: Woods Hole State_or_Province: MA Postal_Code: 02543-1598 Contact_Voice_Telephone: (508) 548-8700 x2266 Contact_Facsimile_Telephone: (508) 457-2310 Contact_Electronic_Mail_Address: dtwichell@usgs.gov Browse_Graphic: Browse_Graphic_File_Name: http://pubs.usgs.gov/of/2003/of03-320/htmldocs/icons/bbasinenh.jpg Browse_Graphic_File_Description: Browse image showing overview of Boulder Basin sidescan-sonar mosaic. Browse_Graphic_File_Type: JPEG Native_Data_Set_Environment: Microsoft Windows XP Version 5.1 (Build 2600) Service Pack 2; ESRI ArcCatalog 9.2.2.1350 Cross_Reference: Citation_Information: Originator: H.E. Bevans Originator: S.L. Goodbred Originator: J.F. Miesner Originator: S.A. Watkins Originator: T.S. Gross Originator: N.D. Denslow Originator: T. Choeb Publication_Date: 1996 Title: Synthetic organic compounds and carp endrocrinology and histology, Las Vegas Wash and Las Vegas and Callville bays of Lake Mead Nevada Series_Information: Series_Name: Water-Resources Investigations Issue_Identification: 96-4266 Publication_Information: Publication_Place: Reston, VA Publisher: U.S. Geological Survey Cross_Reference: Citation_Information: Originator: H.E. Bevans Originator: M.S. Lico Originator: S.J. Lawrence Publication_Date: 1998 Title: Water quality in the Las Vegas Valley area and the Carson and Truckee River basins, Nevada and California, 1992-1996 Series_Information: Series_Name: Circular Issue_Identification: 1170 Publication_Information: Publication_Place: Reston, VA Publisher: U.S. Geological Survey Cross_Reference: Citation_Information: Originator: K.J. Couvay Originator: T.J. Leiker Publication_Date: 1998 Title: Synthetic organic compounds in water and bottom sediment from streams, detention basins, and sewage-treatment plant outfalls in Las Vegas Valley, Nevada, 1997 Series_Information: Series_Name: Open-File Report Issue_Identification: 98-633 Publication_Information: Publication_Place: Reston, VA Publisher: U.S. Geological Survey Cross_Reference: Citation_Information: Originator: H.R. Gould Publication_Date: 1951 Title: Some quantitative aspects of Lake Mead turbidity currents Series_Information: Series_Name: SEPM Special Publication Issue_Identification: No. 2 Publication_Information: Publication_Place: Tulsa, OK Publisher: Society of Economic Paleontologists and Mineralogists Cross_Reference: Citation_Information: Originator: J.F. LaBounty Originator: M.J. Horn Publication_Date: 1997 Title: The influence of drainage from the Las Vegas Valley on the limnology of Boulder Basin, Lake Mead, Arizona-Nevada Series_Information: Series_Name: Journal of Lake and Reservoir Management Issue_Identification: v. 13 Cross_Reference: Citation_Information: Originator: L.J. Paulson Publication_Date: 1981 Title: Nutrient management with hydroelectric dams on the Colorado River Series_Information: Series_Name: Technical Report Issue_Identification: #8 Publication_Information: Publication_Place: Department of Biological Sciences, University of Nevada, Las Vegas, Nevada Publisher: Lake Mead Limnological Research Center Cross_Reference: Citation_Information: Originator: A.M. Preissler Originator: G.A. Roach Originator: K.A. Thomas Originator: J.W. Wilson Publication_Date: 1998 Title: Water resources data, Nevada, water year 1998 Series_Information: Series_Name: Water Resources Data Nevada Issue_Identification: NV-98-1 Publication_Information: Publication_Place: Reston, VA Publisher: U.S. Geological Survey Data_Quality_Information: Logical_Consistency_Report: All these data were collected with the same sidescan-sonar towfish. The majority of the data comprising this mosaic was acquired at a 1500m total swath width. In some small areas, data gaps were filled with data collected at a 750m total swath width. However, in each case, the data were resampled to a 2 m pixel size. Completeness_Report: All imagery necessary to map the lake floor was used. Positional_Accuracy: Horizontal_Positional_Accuracy: Horizontal_Positional_Accuracy_Report: The ship was navigated with P-CODE GPS. The towfish was deployed at approximately the same depth each day, with little variation during the course of the survey. Therefore range to fish values are assumed consistent and accurate. Lineage: Process_Step: Process_Description: Sidescan sonar imagery was collected using a Datasonics SIS-1000 sidescan sonar system and logged to a Triton QMIPS data logging computer. Process_Date: Unknown Process_Step: Process_Description: The digital sidescan data were then processed and mapped to provide proper geographic locations of features identified in the imagery. The processing steps included subsampling the raw sidescan data using a median filtering routine to suppress speckle noise and reduce file size, and corrrect for slant-range distortion, signal attenuation, and dropped sonar lines using XSonar (Danforth et al., 1991). After these processing steps, the imagery was mapped into its proper geographic location using techniques summarized by Paskevich (1996). Individual sidescan swaths were mapped with each pixel geographically positioned at a resolution of 2 m/pixel. Due to the difficult nature of working in a lake environment, XSonar was modified by Danforth to incorporate the ability to exclude portions of the imagery from the beam angle correction routine. This enabled the stark contrast between highly reflection rock outcrops and fine-grained sediment deposits to be preserved. This enhancement was not available in 1999 when the data were collected, so the data were reprocessed in 2001. Processing the data up to this point was done be VeeAnn Cross. Process_Date: Unknown Process_Step: Process_Description: Non-overlapping swaths were then brought into the remote sensing software package PCI. The techniques for generating the composite digital sidscan mosaic are summarized by Paskevich (1992). Processing of the data from this point on was done by David C. Twichell. Process_Date: Unknown Process_Step: Process_Description: Because of the close relationship of the imagery to the topography of the lake, a shaded-relief image generated from the DEM with the 10m contours burned into it was imported to PCI and the sidescan-sonar image strips were georeferenced to it. Misalignments based on the ground control points that were selected between the sidescan-sonar imagery and the DEM after georeferencing were less than 20m in all areas of the lake except a small section of Black Canyon and part of Boulder Canyon. Process_Date: Unknown Process_Step: Process_Description: The mosaic then had a linear stretch applied to the data to reduce the valid data range from 0-255 to 0-254. When mapped on a white background, the background can be made transparent in the GIS without affecting the data. Process_Date: Unknown Process_Step: Process_Description: Once the mosaics were completed, noise and areas of no data were trimmed from the fringes of the completed mosaic. The lake shoreline as defined by the U.S. Bureau of Reclamation was used to trim noise and nodata areas that fell beyond the limits of the lake. Process_Date: Unknown Process_Step: Process_Description: The UTM projected image was the reprojected to Geographic coordinates using BlueMarble's Geographic Transformer software. Transform parameters used a resolution of 2m/pixel and a central latitude of 36N. Process_Date: Unknown Process_Step: Process_Description: Edits to the metadata were made to fix any errors that MP v 2.9.34 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.). Added link to TIFF world file in distribution section. Both geographic and a planar coordinate system were present, the planar one was removed. 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: 20161109 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 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 Spatial_Data_Organization_Information: Direct_Spatial_Reference_Method: Raster Raster_Object_Information: Raster_Object_Type: Pixel Row_Count: 8239 Column_Count: 10644 Vertical_Count: 1 Spatial_Reference_Information: Horizontal_Coordinate_System_Definition: Geographic: Latitude_Resolution: 0.000018 Longitude_Resolution: 0.000022 Geographic_Coordinate_Units: Decimal degrees Geodetic_Model: Horizontal_Datum_Name: D_WGS_1984 Ellipsoid_Name: WGS_1984 Semi-major_Axis: 6378137.000000 Denominator_of_Flattening_Ratio: 298.257224 Entity_and_Attribute_Information: Detailed_Description: Entity_Type: Entity_Type_Label: Band_1 Entity_Type_Definition: Information unavailable from original metadata. Entity_Type_Definition_Source: Information unavailable from original metadata. Attribute: Attribute_Label: ObjectID Attribute_Definition: Internal feature number. Attribute_Definition_Source: ESRI Attribute_Domain_Values: Unrepresentable_Domain: Sequential unique whole numbers that are automatically generated. Overview_Description: Entity_and_Attribute_Overview: The pixel value represents the DN return value of the sidescan-sonar system. A high value (ie 254) indicates a highly reflective lake floor surface, while a low value (ie 0) indicates low reflectance. Entity_and_Attribute_Detail_Citation: U.S. Geological Survey Distribution_Information: Distributor: Contact_Information: Contact_Person_Primary: Contact_Person: David C. Twichell Contact_Organization: U.S. Geological Survey Contact_Position: Oceanographer Contact_Address: Address_Type: mailing and physical address Address: 384 Woods Hole Rd. City: Woods Hole State_or_Province: MA Postal_Code: 02543-1598 Contact_Voice_Telephone: (508) 548-8700 x2266 Contact_Facsimile_Telephone: (508) 457-2310 Contact_Electronic_Mail_Address: dtwichell@usgs.gov Resource_Description: Downloadable Data Distribution_Liability: Although these data have been used by the U.S. Geological Survey (USGS), U.S. Department of the Interior (DOI), no warranty expressed or implied is made by the U.S. Geological Survey as to the accuracy of the data. 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. Standard_Order_Process: Digital_Form: Digital_Transfer_Information: Format_Name: TIFF Format_Version_Number: Information unavailable from original metadata. Format_Specification: GeoTIFF Format_Information_Content: Zip archive containing GeoTIFF image, world file, metadata and browse graphic (optional). File_Decompression_Technique: zip archive Transfer_Size: 28 Digital_Transfer_Option: Online_Option: Computer_Contact_Information: Network_Address: Network_Resource_Name: http://pubs.usgs.gov/of/2003/of03-320/data/sscanimgs/geographic/unenhanced/bbasin_ungeog.tif Network_Resource_Name: http://pubs.usgs.gov/of/2003/of03-320/data/sscanimgs/geographic/unenhanced/bbasin_ungeog.tfw Access_Instructions: Data may be downloaded via the World Wide Web (WWW). Fees: None Technical_Prerequisites: The sidescan sonar mosaic is available as a GeoTIFF image with accompanying world file and georeference report. To utilize this data, the user must have an image viewer, image processing or GIS software package capable of importing a GEOTIFF image. Metadata_Reference_Information: Metadata_Date: 20240318 Metadata_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: 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: whsc_data_contact@usgs.gov Contact_Instructions: The metadata contact email address is a generic address in the event the person is no longer with USGS. (updated on 20240318) Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata Metadata_Standard_Version: FGDC-STD-001-1998 Metadata_Time_Convention: local time Metadata_Access_Constraints: None Metadata_Use_Constraints: None