Identification_Information: Citation: Citation_Information: Originator: Stephen D. Belew Originator: VeeAnn A. Cross Publication_Date: 2003 Title: Hillshade Surface Representing the Floor of Lake Mead and the surrounding area: UTM Projection 30m cellsize Mr.Sid format 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 GIS (ESRI) grid represents the integration swath bathymetry, on land DEM, and underwater surface derived from countour maps generated pre-impoundment. Supplemental_Information: Questions regarding the swath bathymetry portion of this dataset should be directed to Steve Belew, while questions regarding the remainder of the dataset and the integration should be directed to VeeAnn Cross. Time_Period_of_Content: Time_Period_Information: Range_of_Dates/Times: Beginning_Date: 19300000 Ending_Date: 20011100 Currentness_Reference: ground condition Status: Progress: Complete Maintenance_and_Update_Frequency: None planned Spatial_Domain: Bounding_Coordinates: West_Bounding_Coordinate: -114.996607 East_Bounding_Coordinate: -114.003223 North_Bounding_Coordinate: 36.747107 South_Bounding_Coordinate: 35.758065 Keywords: Theme: Theme_Keyword_Thesaurus: General Theme_Keyword: ArcView Theme_Keyword: bathymetry Theme_Keyword: CMGP Theme_Keyword: Coastal and Marine Geology Program Theme_Keyword: DEM Theme_Keyword: digital elevation model Theme_Keyword: grid Theme_Keyword: images Theme_Keyword: lake Theme_Keyword: mosaic Theme_Keyword: OFR03-320 Theme_Keyword: Open-File Report Theme_Keyword: reservoir Theme_Keyword: U.S. Geological Survey Theme_Keyword: USGS Theme_Keyword: Woods Hole Field Center Theme_Keyword: Mr. Sid Theme_Keyword: Bureau of Reclamation Place: Place_Keyword_Thesaurus: General Place_Keyword: Arizona Place_Keyword: Black Canyon Place_Keyword: Boulder Basin Place_Keyword: Colorado River Place_Keyword: Gregg Basin Place_Keyword: Hoover Dam Place_Keyword: Iceberg Canyon Place_Keyword: Lake Mead Place_Keyword: Las Vegas Place_Keyword: Las Vegas Bay Place_Keyword: Las Vegas Wash Place_Keyword: Mohave Desert Place_Keyword: Nevada Place_Keyword: Overton Arm Place_Keyword: United States Place_Keyword: Virgin Basin Place_Keyword: North America Access_Constraints: NONE Use_Constraints: The U.S. Geological Survey and Bureau of Reclamation 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: Steve Belew Contact_Organization: Bureau of Reclamation Contact_Position: GIS Specialist Contact_Address: Address_Type: mailing address Address: P.O. Box 61470 City: Boulder City State_or_Province: NV Postal_Code: 89006-1470 Country: sbelew@usbr.gov Contact_Voice_Telephone: (702) 293-8150 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: Attribute_Accuracy: Attribute_Accuracy_Report: The nature of combining three different datasets tends to reduce the overall accuracy. Therefore a nominal accuracy of 50-100m is assigned to this dataset. Logical_Consistency_Report: This surface represents the integration of three datasets. One is the swath bathymetry data collected in Lake Mead in November of 2001. The second dataset is the on land DEM acquired from the NED (National Elevation Dataset) project. And the final dataset is the surface generated from pre-impoundment elevation contours as digitized from DRG's of Lake Mead (digital raster graphics). Due to the nature of combining these three different datasets, discrepancies are evident at the bounds of each of the datasets. Completeness_Report: This dataset is complete. Positional_Accuracy: Horizontal_Positional_Accuracy: Quantitative_Horizontal_Positional_Accuracy_Assessment: Vertical_Positional_Accuracy: Quantitative_Vertical_Positional_Accuracy_Assessment: Lineage: Process_Step: Process_Description: Three sets of data were acquired. The DEM from the area surrounding Lake Mead was acquired from NED (National Elevation Dataset) in 1998. This data was available as 30m/pixel. The swath bathymetry data was collected in Lake Mead during the fall of 2001. Bureau of Reclamation had this data at a very high resolution. The area covered by this surveying is effectively limited to the areas of post-impoundment sediment. The underwater contours available from the DRG's (digital raster graphics) were digitized. These contours were then used to create an underwater surface using the ESRI topogrid command available in Arc/Info. This surface was created with a 10 m/pixel resolution. Process_Step: Process_Description: The lake bounds shapefile was used to clip the DEM dataset such that all values falling within the lake bounds were turned to NODATA values. Process_Step: Process_Description: The lake bounds shapefile was used to clip the topogrid dataset such that all values falling outside the lake bounds were turned to NODATA values. Process_Step: Process_Description: The high-resolution bathymetry data was resampled to a 10 m cellsize using bilinear interpolation. Process_Step: Process_Description: The swath bathymetry grid was merged with the topogrid surface such that where swath bathymetry data was available, the topogrid surface was overwritten. This provided the present day lakefloor of Lake Mead. Process_Step: Process_Description: The on land DEM was resampled to a 10 m cellsize grid (super sampling). Process_Step: Process_Description: This supersampled on land DEM was then combined with the lake floor surface. Process_Step: Process_Description: The resulting surface then underwent several repetitions of a 4x4 focal mean filtering to remove and null data values and to smooth the transition from one dataset to the next. Process_Step: Process_Description: The surface was then resampled to a 30m cellsize. Process_Step: Process_Description: This grid surface was then used to generate a hillshade relief image in ArcMap using the default settings. Process_Step: Process_Description: The ArcInfo command gridimage was used to convert the hillshade grid to a TIFF image. Process_Step: Process_Description: This TIFF image was then brought into Corel PhotoPaint, version 11, and converted to an 8-bit paletted image and saved with PackBit compression. Process_Step: Process_Description: This TIFF image was then compressed using LizardTech's MrSid Geospatial Encoder version 1.4. Spatial_Data_Organization_Information: Direct_Spatial_Reference_Method: Raster Raster_Object_Information: Raster_Object_Type: Pixel Row_Count: 3586 Column_Count: 2885 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: 30.000000 Ordinate_Resolution: 30.000000 Planar_Distance_Units: meters Geodetic_Model: Horizontal_Datum_Name: North American Datum of 1983 Ellipsoid_Name: Geodetic Reference System 80 Semi-major_Axis: 6378137.000000 Denominator_of_Flattening_Ratio: 298.257222 Entity_and_Attribute_Information: Detailed_Description: Entity_Type: Entity_Type_Label: Band_1 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. Attribute: Attribute_Label: Value Attribute: Attribute_Label: Count Distribution_Information: Distributor: 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 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: 0.841 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