David C. Twichell
VeeAnn A. Cross
2003
Chirp Seismic Shotpoint Navigation every 500 shots in Geographic Coordinates - Lake Mead Survey 1999
vector digital data
David C. Twichell
VeeAnn A. Cross
2003
Mapping the floor of Lake Mead (Nevada and Arizona): Preliminary discussion and GIS data release
1.0
Open-File Report
03-320
Woods Hole Field Center, Woods Hole, MA
U.S. Geological Survey
Stephen D. Belew
lm99_500sht
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.
This ArcView shapefile is used to enable correlation between the seismic-reflection profiles and the sidescan-sonar imagery, geologic interpretation, and other features represented on the lake floor.
en
19990514
19990525
ground condition
None planned
-114.857590
-114.592365
36.145382
36.019699
-114.857590-114.59236536.01969936.145382
General
seismic
navigation
point
chirp
subbottom
SIS-1000
shotpoint
U.S. Geological Survey
USGS
Coastal and Marine Geology Program
CMGP
Woods Hole Field Center
Open-File Report
OFR03-320
cruise serial number 99014
General
Nevada
Lake Mead
Hoover Dam
Boulder Basin
Mojave Desert
United StatesNorth America
none
The U.S. Geological Survey must be referenced as the originator of the dataset in any future products or research derived from these data.
David C. Twichell
U.S. Geological Survey
Oceanographer
mailing and physical address
384 Woods Hole Rd.
Woods Hole
MA
02543-1598
508-548-8700 x2266
508-457-2310
dtwichell@usgs.gov
Microsoft Windows 2000 Version 5.0 (Build 2195) Service Pack 3; ESRI ArcCatalog 8.2.0.700
ShapefileSynthetic organic compounds and carp endrocrinology and histology, Las Vegas Wash and Las Vegas and Callville bays of Lake Mead NevadaH.E. BevansS.L. GoodbredJ.F. MiesnerS.A. WatkinsT.S. GrossN.D. DenslowT. Choeb1996Water-Resources Investigations96-4266U.S. Geological SurveyWater quality in the Las Vegas Valley area and the Carson and Truckee River basins, Nevada and California, 1992-1996H.E. BevansM.S. LicoS.J. Lawrence1998Circular1170U.S. Geological SurveySynthetic organic compounds in water and bottom sediment from streams, detention basins, and sewage-treatment plant outfalls in Las Vegas Valley, Nevada, 1997K.J. CouvayT.J. Leiker1998Open-File Report98-633U.S. Geological SurveyArchive of Seismic-Reflection Data Collected During USGS Cruise Lake Mead 99014 in Lake Mead - Nevada and Arizona, 14-25May, 1999V.A. CrossD.C. Twichell2003Open-File Report03-003U.S. Geological SurveySome quantitative aspects of Lake Mead turbidity currentsH.R. Gould1951SEPM Special PublicationNo. 2Society of Economic Paleontologists and MineralogistsThe influence of drainage from the Las Vegas Valley on the limnology of Boulder Basin, Lake Mead, Arizona-NevadaJ.F. LaBountyM.J. Horn1997Journal of Lake and Reservoir Managementv. 13Nutrient management with hydroelectric dams on the Colorado RiverL.J. Paulson1981Technical Report#8Department of Biological Sciences, University of Nevada, Las Vegas, NevadaLake Mead Limnological Research CenterWater resources data, Nevada, water year 1998A.M. PreisslerG.A. RoachK.A. ThomasJ.W. Wilson1998Water Resources Data NevadaNV-98-1U.S. Geological Survey
These data have been checked to remove obviously erroneous data points.
These data represent shotpoint navigation for all the chirp seismic lines collected on this cruise.
This particular seismic data was acquired with an SIS-1000 chirp subbottom system with the digital data stored on a Triton-QMIPS datalogger. Navigation is updated approximately every 10 seconds and sent to this data logging system. Once the seismic SEG-Y data is separated from the raw data files, the unique navigation points and the shotpoints associated with them are pulled from the header of these seg-y data files. These navigation positions reflect the best known position of the acquisition system. In other words, the layback of the instrument is taken into account for the positional fix.
The shot point navigation for each line of seismic data was combined into a single file and then resampled using DigiRule's GeoCad program to a shot interval of 500. The beginning and ending shot of each line was maintained.
These points were then imported into ArcView and saved as a shapefile.
Since the original navigation was stored in the SEG-Y header in UTM, zone 11, NAD 83 meters, the file was then reprojected to the Geographic Coordinate system using ArcToolbox in ArcGIS 8.1
20mThe navigation was collected with a P-CODE GPS receiver with an assumed accuracy of approximately 10m. Additional error is introduced by undertainty as to the positional relationship between the acquisition system and the navigation antenna.
Vector
Entity point
616
SimplePointFALSE616TRUEFALSE
0.0002
0.0002
Decimal degrees
North American Datum of 1983
Geodetic Reference System 80
6378137.000000
298.257222
GCS_North_American_1983
lm99_500sht
ArcView shapefile attribute table
ESRI
Feature Class616
FID
Internal feature number.
ESRI
Sequential unique whole numbers that are automatically generated.
FIDOID400
Shape
Feature geometry.
ESRI
Coordinates defining the features.
ShapeGeometry000
EASTING
The UTM easting position of the shot point.
software generated
692808
716830
meters
EASTINGNumber112
NORTHING
The UTM northing position of the shot point.
software generated.
3988421
4002759
meters
NORTHINGNumber122
SHOT
The seismic shot number corresponding to that point.
software computed.
1
8654
SHOTNumber4
LINENUM
Line number assigned to the seismic line along which the shotpoint navigation point falls.
data processor.
character set
LINENUMString8
David C. Twichell
U.S. Geological Survey
Oceanographer
mailing and physical address
384 Woods Hole Rd.
Woods Hole
MA
02543
508-548-8700 x2266
508-457-2310
dtwichell@usgs.gov
Downloadable Data
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.
0.065
0.069
20030123
Marine Geologist
mailing and physical address
384 Woods Hole Rd.
Woods Hole
MA
02543-1598
508-548-8700 x2251
508-457-2310
vatnipp@usgs.gov
VeeAnn A. CrossU.S. Geological Survey
FGDC Content Standards for Digital Geospatial Metadata
FGDC-STD-001-1998
local time
none
none
enhttp://www.esri.com/metadata/esriprof80.htmlESRI Metadata Profile
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