Isopach Map of Postimpoundment Sediment in Lake Mead - Geographic Coordinates

Metadata:

• Identification_Information
• Data_Quality_Information
• Spatial_Data_Organization_Information
• Spatial_Reference_Information
• Distribution_Information
• Metadata_Reference_Information

Identification_Information:

Citation:

Citation_Information:

Originator: David C. Twichell

Originator: VeeAnn A. Cross

Publication_Date: 2003

Title:

Isopach Map of Postimpoundment Sediment in Lake Mead - Geographic Coordinates

Geospatial_Data_Presentation_Form: raster digital data

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

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 of three datasets collected in 1999-2001 and represents the sediment thickness in Lake Mead as mapped with seismic-reflection equipment.

Time_Period_of_Content:

Time_Period_Information:

Range_of_Dates/Times:

Beginning_Date: 19990514

Ending_Date: 20010426

Currentness_Reference: ground condition

Status:

Progress: Complete

Maintenance_and_Update_Frequency: None planned

Spatial_Domain:

Bounding_Coordinates:

West_Bounding_Coordinate: -114.888307

East_Bounding_Coordinate: -114.006721

North_Bounding_Coordinate: 36.503170

South_Bounding_Coordinate: 35.994301

Keywords:

Theme:

Theme_Keyword_Thesaurus: General

Theme_Keyword: ArcView

Theme_Keyword: CMGP

Theme_Keyword: Coastal and Marine Geology Program

Theme_Keyword: grid

Theme_Keyword: isopach

Theme_Keyword: OFR03-320

Theme_Keyword: Open-File report

Theme_Keyword: sediment

Theme_Keyword: sediment thickness

Theme_Keyword: U.S. Geological Survey

Theme_Keyword: USGS

Theme_Keyword: Woods Hole Field Center

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: Mojave 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 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:

This isopach map represents the integration of three years of data collection. This time frame of data collection can introduce small discrepancies in the sediment thickness.

Completeness_Report: This dataset is complete for the time period it covers.

Positional_Accuracy:

Horizontal_Positional_Accuracy:

Horizontal_Positional_Accuracy_Report:

The navigation system used was a P-Code GPS system. Navigation was interpolated over as much as a 10 second interval, converted to UTM zone 11 coordinates and rounded to the nearest meter.

Quantitative_Horizontal_Positional_Accuracy_Assessment:

Horizontal_Positional_Accuracy_Value: 10-20m

Horizontal_Positional_Accuracy_Explanation: Nominal accuracy for the system and including rounding errors.

Vertical_Positional_Accuracy:

Vertical_Positional_Accuracy_Report:

The nominal resolution of the chirp subbottom system is assumed to be 0.5 meters. Another uncertainty is the speed of sound in sediment, which for this study is assumed to be 1500 m/sec. Due to the generally thin nature of the sediment cover, inaccuracies in the speed of sound are not thought to have a high impact.

Quantitative_Vertical_Positional_Accuracy_Assessment:

Vertical_Positional_Accuracy_Value: 0.5 meters

Vertical_Positional_Accuracy_Explanation: acquisition system resolution

Lineage:

Process_Step:

Process_Description:

Seismic-reflecition profiles were interpreted in Landmark seismic interpretation software. The interpreted surfaces included the pre- and post-impoundment surfaces.

Process_Step:

Process_Description:

A supplemental horizon was created within Landmark which is the difference between the pre-and post-impoundment surfaces.

Process_Step:

Process_Description:

This thickness horizon was then exported from Landmark as X,Y,Z values in ASCII format.

Process_Step:

Process_Description:

This ASCII X,Y,Z file was then imported into Earthvision software package. Within Earthvision, these discrete points were gridded using the default spline gridding technique of earthvision.

Process_Step:

Process_Description:

The Earthvision grid was then exported as an X,Y,Z ASCII text file.

Process_Step:

Process_Description:

The Earthvision ASCII text file was then reformatted using an AWK script into an ESRI ASCII grid format.

Process_Step:

Process_Description:

The ESRI ASCII grid format was imported into ArcView and converted to the standard ESRI grid format.

Process_Step:

Process_Description: This grid was then clipped to the sediment limit shapefile.

Process_Step:

Process_Description:

This UTM grid was then reprojected to the geographic coordinate system using ArcToolbox from ArcGIS version 8.2.

Spatial_Data_Organization_Information:

Direct_Spatial_Reference_Method: Raster

Raster_Object_Information:

Raster_Object_Type: Grid Cell

Row_Count: 2022

Column_Count: 3503

Vertical_Count: 1

Spatial_Reference_Information:

Horizontal_Coordinate_System_Definition:

Geographic:

Latitude_Resolution: 0.000252

Longitude_Resolution: 0.000252

Geographic_Coordinate_Units: Decimal degrees

Planar:

Planar_Coordinate_Information:

Planar_Coordinate_Encoding_Method: row and column

Coordinate_Representation:

Abscissa_Resolution: 0.000252

Ordinate_Resolution: 0.000252

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

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 of 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: 27.770

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