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Prepared in cooperation with the Iowa Department of Natural Resources

Bathymetric Contour Maps for Lakes Surveyed in Iowa in 2003

By S. Mike Linhart and Kris D. Lund

U.S. Geological Survey Scientific Investigations Map 2933

AVAILABLE ONLINE ONLY


Data-Collection Points Along Transects and Around Perimeter of Lake Meyer, Winnishiek County, Iowa

Metadata also available as

Metadata:


Identification_Information:
Citation:
Citation_Information:
Originator:
U.S. Geological Survey, Iowa Water Science Center, Eastern Iowa Field Unit, Iowa City, Iowa
Publication_Date: 2006
Title:
Data-Collection Points Along Transects and Around Perimeter of Lake Meyer, Winnishiek County, Iowa
Geospatial_Data_Presentation_Form: vector digital data
Series_Information:
Series_Name: Scientific Investigations Map 2933-D
Publication_Information:
Publisher: U.S. Geological Survey
Online_Linkage: None
Description:
Abstract:
Point coverage of bathymetry data for Lake Meyer in Winneshiek Co., Iowa. The U.S. Geological Survey conducted a bathymetric survey of Lake Meyer in 2003.
Purpose:
This digital, geographically referenced data set was developed by the U.S. Geological Survey to be used with the Lake Bathymetric project, Eastern Field Unit, Iowa City, Iowa.
Supplemental_Information:
Data collected during the bathymetric survey were input into a geographic information system (GIS) software package, ArcInfo, to create a point coverage representing discrete point locations. This point coverage (among other coverages) was then used to generate a three-dimensional surface representing the lake-bottom elevation.
Time_Period_of_Content:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date: 2003
Ending_Date: present
Currentness_Reference: ground condition
Status:
Progress: Complete
Maintenance_and_Update_Frequency: None planned
Spatial_Domain:
Bounding_Coordinates:
West_Bounding_Coordinate: -91.914336
East_Bounding_Coordinate: -91.904933
North_Bounding_Coordinate: 43.176394
South_Bounding_Coordinate: 43.172823
Keywords:
Theme:
Theme_Keyword_Thesaurus: None
Theme_Keyword: Lakes
Theme_Keyword: Bathymetry
Theme_Keyword: Inland Waters
Theme_Keyword: Hydrology
Theme_Keyword: USGS
Place:
Place_Keyword: Iowa
Access_Constraints:
This digital, geographically referenced data set was developed by the U.S. Geological Survey to be used with the Lake Bathymetric project, Eastern Field Unit, Iowa City, Iowa.
Use_Constraints:
The data are released on condition that neither the USGS nor the United States Government may be held liable for any damages resulting from its authorized or unauthorized use.
Point_of_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: U.S. Geological Survey
Contact_Person: Greg Nalley
Contact_Position: Project Chief - Eastern Field Unit Supervisory Hydrologist
Contact_Voice_Telephone: 319-337-4191
Contact_Facsimile_Telephone: 319-358-3606
Contact_Electronic_Mail_Address: gmnalley@usgs.gov
Native_Data_Set_Environment:
Microsoft Windows XP Version 5.1 (Build 2600) Service Pack 2; ESRI ArcCatalog 9.1.0.722

Data_Quality_Information:
Attribute_Accuracy:
Completeness_Report:
Point coverage of weeded bathymetry data points collected along transects and the lake perimeter using the 200-KHz transducer. Data points were weeded prior to generation of this coverage using a macro in the text editor, EMACS. Data were weeded from 5,524 to 1,838 data points and used for input into a TIN model.
Positional_Accuracy:
Horizontal_Positional_Accuracy:
Horizontal_Positional_Accuracy_Report:
Accuracy is tested by visual comparison of source with digital data on an interactive computer system.
Lineage:
Source_Information:
Source_Citation:
Citation_Information:
Type_of_Source_Media: computer program
Source_Time_Period_of_Content:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date: 2003
Ending_Date: present
Process_Step:
Process_Description:
Data collection: Bathymetry data were collected using the BSS+5 bathymetric survey system with a 200-kHZ intelligent depth sounder (IDS) and a differential GPS (Novatel DGPS beacon or Omnistar receiver) (Specialty Devices, Inc., 2003, Bathymetric Survey System BSS+5 with Omnistar manual: Specialty Devices, Inc., Plano, Texas, 38 p.). The differential GPS has a horizontal accuracy of less than 1 meter (3.281 ft). Bathymetry data were collected and stored in Hypack Max software (ver. 2.12a) (Hydrographic Survey Software, User's Manual, Hypack Max, Coastal Oceanographics, Inc., Middlefield, Conn.). In Hypack Max, the geodetic parameters were set to UTM north, Zone 15, and ellipsoid GRS-1980. Distance (easting and northing) and depth units were both collected in feet.

A bar check calibration on the echo sounder was performed at the start of each day following established protocols (U.S. Army Corps of Engineers, 1994, Engineering and design: Hydrographic survey EM 1110-2-1003, chap. 9-3, p. 9-4 to 9-9). This was done to ensure that the echo sounder was calibrated correctly. The bar check involves suspending a 2-ft-diameter flat aluminum plate directly below the echo sounder. The suspension line is marked in 5-ft increments. An initial calibration is made at 5 ft by entering the speed of sound in water (based on water temperature) and then adjusting the offset of the transducer in the computer software. The offset is the draft of the transducer below the lake surface. The aluminum plate is then lowered in 5-ft increments (depending on the range of depths expected to be encountered on the day of data collection) and adjustments in the speed of sound are made until depth readings and the depth of the aluminum plate agree to within approximately 0.1 ft.

Data were collected along planned transect lines that were set-up in Hypack Max prior to data collection. Transect lines were spaced at 50-ft intervals perpendicular to the long axis of Lake Meyer. Depending on boat speed, one bathymetry data point was collected at approximately 4- to 8-ft intervals. Data points may be much closer in areas where transect or perimeter runs overlap. Perimeter bathymetry data points were collected while driving the boat around the perimeter of the lake. Target points were collected in areas of the lake where it was too shallow to collect data with the BSS+5 system. Target point depths were collected manually along with a corresponding easting and northing location. The number and location of target points were based on a judgment made in the field that was thought to be spatially representative of the area. In addition, shore point locations (easting and northing) were collected to define the edge of the lake. These locations are collected by touching the bow of the boat to the shoreline at various intervals along the shoreline and recording the position using a bow-mounted GPS antenna.

The water-surface elevation of Lake Meyer was determined by tape down (using a steel tape) from a reference point (with a known elevation) on the concrete outflow structure at the dam. The elevation of the reference point was determined by surveying from a reference mark (temporary wooden stake) nearby on the dam. The elevation (1142.388 ft NAVD88) for the reference mark (wooden stake) was determined from third-order benchmarks using an Ashtech Z-12 GPS system. The elevation of the reference point was found to be 1139.180 ft (NAVD88). The water-surface elevation was found to be 1135.76 ft (NAVD88) on July 21, 2003.

Post-processing: Bathymetry data were processed using the Hypack Max software. Post-processing involved removing obvious spikes, inputting depths for the time-tagged target points, and editing extraneous points within the shore point files. In addition, tide corrections were applied in Hypack Max to convert depths to elevations. For Lake Meyer data, it was found that some bathymetry data was lost in the deepest parts of the lake (in the old creek channel near the dam). This was due to improper gate selection in SDIDepth software (Specialty Devices, Inc., 2003, Bathymetric Survey System BSS+5 with omnistar manual: Specialty Devices, Inc., Plano, Texas, 38 p.) which controls the range in which data can be collected. SDIDepth is the software which collects seismic digital data but is also where parameters controlling transducer operation are entered. This software communicates with Hypack Max during data collection. Lost bathymetric data for these areas were recovered by exporting the depths recorded by DepthPic software (used to digitize the bottom layer of recent sediment) (Specialty Devices, Inc., 2003, Bathymetric Survey System BSS+5 with omnistar manual: Specialty Devices, Inc., Plano, Texas, 38 p.) into XYZ format. The processed bathymetry data in Hypack Max also were exported to XYZ format. A total of three separate files were exported into XYZ format: (1) the transect and perimeter bathymetric data; (2) the shore point location data; (3) and the target point data. All three XYZ files were then converted to ASCII text files for input into ESRI-ArcGIS (ver. 8.3).

NOTE: All bathymetry data processed in Hypack Max and subsequently exported to XYZ and text files were based on an incorrect water-surface elevation (1138.97 ft instead of 1135.76 ft) due to transcription error. Corrections were not made in Hypack Max or the XYZ and text files but were made in the coverage INFO files in ARC.

Generation of Bathymetry Map: The output text files (containing northing, easting, and elevation) were input into an arc macro language (AML) script called createpoint in ARC to generate the coverages mey_allpts83, mey_targpts83, and mey_edgepts83. Projections for the coverages were then defined in ARC as UTM zone 15, NAD83, and units in feet.

In ARC, the mey_allpts83 coverage was processed through the WEEDPOINT command but the points were not weeded throughout the coverage extent. After several failed attempts to use the WEEDPOINT command, the points were weeded out in the original text file (mey_allpoints.txt) using a macro in the text editor, EMACS. Of the original 5,524 data points, 1,838 data points remained after weeding. The text file (mey_tinpoints.txt) of the weeded bathymetry data was then input into createpoint in ARC to generate the coverage mey_tinpts. The mey_tinpts coverage was then projected to create the coverage mey_tinpts83 for input into a TIN model.

Using 3-D Analyst in ArcMap, a TIN model (mey_tin) was generated using the mey_tinpts83 and mey_targpts83 point coverages triangulated as mass points. Height source was "elevation". The mey_bndry83 arc was input as a hard line with a height source as "elev" (elevation value = 1135.76 ft). The mey_bndry83 coverage (polygon) was input as a hard clip to clip the TIN to the lake shoreline.

Process_Date: 2004

Spatial_Data_Organization_Information:
Direct_Spatial_Reference_Method: Vector
Point_and_Vector_Object_Information:
SDTS_Terms_Description:
SDTS_Point_and_Vector_Object_Type: Entity point
Point_and_Vector_Object_Count: 1838
SDTS_Terms_Description:
SDTS_Point_and_Vector_Object_Type: Point
Point_and_Vector_Object_Count: 4

Spatial_Reference_Information:
Horizontal_Coordinate_System_Definition:
Planar:
Map_Projection:
Map_Projection_Name: Transverse Mercator
Transverse_Mercator:
Scale_Factor_at_Central_Meridian: 0.999600
Longitude_of_Central_Meridian: -93.000000
Latitude_of_Projection_Origin: 0.000000
False_Easting: 1640416.666667
False_Northing: 0.000000
Planar_Coordinate_Information:
Planar_Coordinate_Encoding_Method: coordinate pair
Coordinate_Representation:
Abscissa_Resolution: 0.000005
Ordinate_Resolution: 0.000005
Planar_Distance_Units: survey feet
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
Vertical_Coordinate_System_Definition:
Altitude_System_Definition:
Altitude_Datum_Name: North American Vertical Datum of 1988
Altitude_Distance_Units: feet

Entity_and_Attribute_Information:
Detailed_Description:
Entity_Type:
Entity_Type_Label: mey_tinpts83.pat
Attribute:
Attribute_Label: FID
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: Shape
Attribute_Definition: Feature geometry.
Attribute_Definition_Source: ESRI
Attribute_Domain_Values:
Unrepresentable_Domain: Coordinates defining the features.
Attribute:
Attribute_Label: AREA
Attribute_Definition: Area of feature in internal units squared.
Attribute_Definition_Source: ESRI
Attribute_Domain_Values:
Unrepresentable_Domain:
Area is always zero for point coverages. Values are automatically generated.
Attribute:
Attribute_Label: PERIMETER
Attribute_Definition: Perimeter of feature in internal units.
Attribute_Definition_Source: ESRI
Attribute_Domain_Values:
Unrepresentable_Domain:
Perimeter is always zero for point coverages. Values are automatically generated.
Attribute:
Attribute_Label: MEY_TINPTS83#
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: MEY_TINPTS83-ID
Attribute_Definition: User-defined feature number.
Attribute_Definition_Source: ESRI
Attribute:
Attribute_Label: EASTING
Attribute:
Attribute_Label: NORTHING
Attribute:
Attribute_Label: ELEVATION

Distribution_Information:
Distributor:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization:
Lake Bathymetric Project, U.S. Geological Survey, Iowa City, Iowa
Contact_Person: Greg Nalley
Contact_Position: Project Chief
Contact_Address:
Address_Type: mailing address
Address: PO Box 1230
City: Iowa City
State_or_Province: Iowa
Postal_Code: 52244
Country: USA
Contact_Voice_Telephone: 319-337-4191
Contact_Facsimile_Telephone: 319-358-3606
Contact_Electronic_Mail_Address: gmnalley@usgs.gov
Resource_Description: None
Distribution_Liability:
The Lake Bathymetric project of the Eastern Field Unit, the Water Resources Discipline (WRD), and the U.S. Geological Survey make no guarantee nor offer any warranty concerning the accuracy, condition, or application of the information contained in these geographic data.

The burden for determining fitness for use of this data lies entirely with the user. Although these data have been processed successfully on computers of WRD, no warranty, expressed or implied, is made by WRD regarding the use of these data on any other system, nor does the fact of distribution constitute or imply any such warranty.

In no event shall the WRD have any liability whatsoever for payment of any consequential, incidental, indirect, special, or tort damages of any kind, including, but not limited to, any loss of profits arising out of the delivery, installation, operation, or support by WRD.

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:
Transfer_Size: 0.208

Metadata_Reference_Information:
Metadata_Date: 20060725
Metadata_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: U.S. Geological Survey
Contact_Person: Mike Linhart
Contact_Position: Hydrologist
Contact_Address:
Address_Type: mailing address
Address: PO Box 1230
City: Iowa City
State_or_Province: Iowa
Postal_Code: 52244
Country: USA
Contact_Voice_Telephone: 319-337-4191
Contact_Facsimile_Telephone: 319-358-3606
Contact_Electronic_Mail_Address: slinhart@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

Generated by mp version 2.8.6 on Tue Jul 25 09:58:47 2006

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