[Parameters: Topic='OCEANS', Term='BATHYMETRY/SEAFLOOR TOPOGRAPHY', Variable_Level_1='WATER DEPTH']
Bathymetry of Lake Erie and Lake Saint ClairEntry ID: gov.noaa.ngdc.mgg.dem.312
Abstract: ABSTRACT: Bathymetry of Lake Erie and Lake Saint Clair has been compiled as a component of a NOAA project to rescue Great Lakes lake floor geological and geophysical data and make it more accessible. This project is a cooperative effort between investigators at the NOAA National Geophysical Data Center's Marine Geology and Geophysics Division (NGDC/MGG), the NOAA Great Lakes Environmental Research ... Laboratory (GLERL) and the Canadian Hydrographic Service(CHS). Bathymetric sounding data employed in compiling the one-meter bathymetry (National Geophysical Data Center, 1998) were collected over a 100-year period for purposes of navigation safety and nautical charting by the U. S. Army Corps of Engineers, the NOAA Coast Survey, and the Canadian Hydrographic Service. These bathymetric data, totaling several hundred thousand soundings, are separated four ways in existing archives: by whether they exist in digital form or reside only on paper sheets; and by whether they were collected by the U. S. or Canada. Final assembly of the new bathymetry has resulted from synthesis of bathymetric data from the four sources. Spacing of data control tracklines ranges from 500 to 2500 meters for the open lake and from 125 to 500 meters for nearshore areas. In preparation for bathymetric contouring, digital soundings were converted to metric units and computer plotted in color according to depth range. Contours in metric units were generated directly on overlays from paper sheets and then reduced to compilation scale and patched in. Compilation sheets were scanned and vectorized; and the resulting digital bathymetric contour data constitutes the primary product. The data were hand contoured by geomorphologists to capture and portray the maximum information available, resulting in a degree of detail not attainable with machine contouring and the density of available data. Bathymetric contours were prepared by geologists using sounding data contained in the paper archives at the scale of the survey sheets (scales ranging from 1: 100,000 to 1: 10, 000); or from sounding data contained in digital data bases at standard scales of either 1: 100,000 or 1: 50,000. Details concerning the methods of compilation are given in the western Lake Erie paper (Holcombe, et al., 1997). Bathymetric contours have been spatially reconciled with the NOAA Coast Survey nominal scale 1:80,000 digital vector shoreline, which by definition coincides with the Lake Erie low water datum, the zero-depth employed for bathymetric surveys and nautical charting.
SUPPLEMENTAL INFORMATION: Supplemental information regarding spatial reference. Contours are vertically referenced to lake levels. Gridded data is vertically referenced to lake level or sea level as set by user in online tool "Design-a-Grid" advanced options. The Lake Erie shoreline is a horizontal datum referenced to NAD1983. It is not referenced to a vertical datum. This is because actual lake-surface elevation is time-variant in two ways: 1)Lake level varies daily and seasonally with the changing precipitation and water budget, and 2) Lake elevation is increasing with time as a function of isostatic rebound - also the elevation increase with time varies with location on the lake (differential isostatic rebound). IGLD85 elevation currently assigned to the Lake Erie low-water datum is 173.5 meters. For purposes of navigation safety, the low water datum is lower than any historic lake Erie levels known to have occurred in the past. All the bathymetry is adjusted to this datum. Great Lakes bathymetry is normally expressed as depth below the low water datum. Attempting to reference Great Lakes depths to elevation above sea level is usually not recommended.
CURRENTNESS REFERENCE: publication date
SPATIAL REFERENCE INFORMATION - 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
Data Set ID: _Great_Lakes_Bathymetry,_Lake_Erie_and_Lake_St._Clair__Great_Lakes_Bathymetry,_Lake_Erie_and_Lake_St._Clair_
Fees: Download online no charge. CD-ROM: 25 USD plus shipping and handling. USD plus shipping and handling
Purpose: PURPOSE: Scientific Research, Commercial Exploration, Fishing, Policy and Decision-making
Data Set Citation
Dataset Originator/Creator: Albert Simard
Dataset Title: Forest fires in Canada, 1975—1995
Dataset Series Name: Sustaining Canada's Forests: Timber Harvesting - Technical Supplement: Forest fire disturbance
Dataset Release Place: Canada
Dataset Publisher: Environment Canada
Start Date: 1975-01-01Stop Date: 1995-12-31
Sustaining Canada's Forests: Timber Harvesting. 1999. Canadian Forest Service, Departments of Environment and Natural Resources, Ottawa, Ontario. Catalogue No. EN 1-19/00-4B, ISSN 1192-4454.
Canadian Council of Forest Ministers. 1996. Compendium of Canadian Forestry Statistics. Canadian Forest Service. National Forestry Database Program. Ottawa, Ontario.
Haddon, B.D. (ed.). 1988. Forest Inventory Terms in Canada. Third Edition. Published by Canadian Forest Service for the Canadian Forest Inventory Committee. Ottawa, Ontario.
Simard, A. 1997. Towards Criteria and Indicators for Wildland Fire — A Canadian Example. Presented at the 2nd International Conference on Wildland Fire. May 25—30, 1997. Natural Resources Canada.
Creation and Review Dates
DIF Creation Date: 2008-09-05
Last DIF Revision Date: 2012-02-14