Identification_Information: Citation: Citation_Information: Originator: David C. Twichell Originator: VeeAnn A. Cross Publication_Date: 2003 Title: Enhanced TIFF Sidescan-Sonar Mosaic of Las Vegas Wash - Lake Mead, Nevada: UTM Projection Geospatial_Data_Presentation_Form: remote-sensing image Online_Linkage: 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: Woods Hole Field Center, Woods Hole, MA Publisher: U.S. Geological Survey 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: 20000601 Ending_Date: 20000606 Currentness_Reference: ground condition Status: Progress: Complete Maintenance_and_Update_Frequency: None planned Spatial_Domain: Bounding_Coordinates: West_Bounding_Coordinate: -114.877685 East_Bounding_Coordinate: -114.805620 North_Bounding_Coordinate: 36.139662 South_Bounding_Coordinate: 36.109835 Keywords: Theme: Theme_Keyword_Thesaurus: General 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: TIFF Theme_Keyword: U.S. Geological Survey Theme_Keyword: USGS Theme_Keyword: Woods Hole Field Center Place: Place_Keyword_Thesaurus: General Place_Keyword: Lake Mead Place_Keyword: Las Vegas Place_Keyword: Las Vegas Bay Place_Keyword: Las Vegas Wash 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. 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 Native_Data_Set_Environment: Microsoft Windows 2000 Version 5.0 (Build 2195) Service Pack 4; ESRI ArcCatalog 8.2.0.700 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: 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: 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: 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: 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: Publisher: U.S. Geological Survey Data_Quality_Information: Logical_Consistency_Report: All of these data were collected with the same sidescan-sonar towfish - the Edgetech DF1000. All data were collected as 16-bit, 200m swath, 1024 pixels/side. Completeness_Report: All imagery necessary to map the lake floor of interest in this particular study 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. Due to the shipboard configuration, the navigation antennae was placed at the approximate layback position of the towfish, therefore range to fish errors are assumed to be negligible. Lineage: Process_Step: Process_Description: Sidescan sonar imagery was collected using an Edgetech DF1000 sidescan sonar system and logged to a Triton QMIPS data logging computer. All of the data were collected at a 200m swath, 1024 pixels/side, 16-bit. 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 attentuation, and dropped sonar lines using XSonar (Danforth et al., 1991). Source_Used_Citation_Abbreviation: Danforth, W.W., O'Brien, T.F., and Schwab, W.C., 1991, USGS image processing system: near real-time mosaicking of high-resolutoin sidescan-sonar data: Sea Technology, Jan., 1991, p. 54-59. Process_Date: 20000600 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: 384 Woods Hole Rd. City: Woods Hole State_or_Province: MA Postal_Code: 02543 Country: USA 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 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 1 m/pixel. Source_Used_Citation_Abbreviation: Paskevich, V.F., 1996, MAPIT: An improved method for mapping digital sidescan sonar data using the Woods HOle Image Processing System (WHIPS) software: U.S. Geological Survey Open-File Report 96-281, 73p. Process_Date: 20000600 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: 384 Woods Hole Rd. City: Woods Hole State_or_Province: MA Postal_Code: 02543 Country: USA Contact_Voice_Telephone: 508-548-8700 x2251 Contact_Facsimile_Telephone: 508-457-2310 Contact_Electronic_Mail_Address: vatnipp@usgs.gov 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). A root stretch from 0-254 was applied to the sidescan image. The imagery portion was then cut out and written to a PCI channel with a white background. By doing this, within ArcView the user can turn the 255 pixel value to transparent and only display the actual sidescan imagery. This enhanced image was then exported from PCI as a TIFF image with an associated world file for georeferencing purposes. Source_Used_Citation_Abbreviation: Paskevich, V.F., 1992, Digital mapping of sidescan sonar data with the Woods Hole Image Processing System software: U.S. Geological Survey Open-File Report 92-536, 87p. Process_Date: 20000600 Process_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 Country: USA Contact_Voice_Telephone: 508-548-8700 x2266 Contact_Facsimile_Telephone: 508-457-2310 Contact_Electronic_Mail_Address: dtwichell@usgs.gov Spatial_Data_Organization_Information: Direct_Spatial_Reference_Method: Raster Raster_Object_Information: Raster_Object_Type: Pixel Row_Count: 3168 Column_Count: 6419 Vertical_Count: 1 Spatial_Reference_Information: Horizontal_Coordinate_System_Definition: Planar: Grid_Coordinate_System: Grid_Coordinate_System_Name: Universal Transverse Mercator Universal_Transverse_Mercator: UTM_Zone_Number: 11 Transverse_Mercator: Scale_Factor_at_Central_Meridian: 0.999600 Longitude_of_Central_Meridian: -117.000000 Latitude_of_Projection_Origin: 0.000000 False_Easting: 500000.000000 False_Northing: 0.000000 Planar_Coordinate_Information: Planar_Coordinate_Encoding_Method: row and column Coordinate_Representation: Abscissa_Resolution: 1.000000 Ordinate_Resolution: 1.000000 Planar_Distance_Units: meters 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: 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. 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: These data were prepared by an agency of the United States Government. Neither the United States government nor any agency thereof, nor any of their employees, make any warranty, expressed or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed in this report, or represents that its use would not infringe privately owned rights. Reference therein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States government or any agency thereof. Any views and opinions of authors expressed herein do not necessarily state or reflect those of the United States government or any agency thereof. Although all data published in this report have been used by the USGS, no warranty, expressed or implied, is made by the USGS as to the accuracy of the data and related materials and/or the functioning of the software. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of this data, software, or related materials. Standard_Order_Process: Digital_Form: Digital_Transfer_Information: Transfer_Size: 3.949 Metadata_Reference_Information: Metadata_Date: 20031006 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: vatnipp@usgs.gov Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata Metadata_Standard_Version: FGDC-STD-001-1998 Metadata_Time_Convention: local time Metadata_Extensions: Online_Linkage: http://www.esri.com/metadata/esriprof80.html Profile_Name: ESRI Metadata Profile