Bathymetric surface grid derived from bathpt95.
Bathymetric surveys were conducted in 1867, 1957, and 1994/1995.
E&S performed a comparative analysis for TBNEP of the
available historical bathymetric data sets for the bay. The
objective of this analysis was to quantify, to the extent
possible, the changes in bathymetry that occurred between
the times of the available surveys.
Purpose:
We developed bathymetric maps for each of the data sets
in a consistent fashion. This allowed direct comparison
between surveys to permit quantification of the changes
that occurred in the depth of the bay during the intervening
periods. . The
objective of this analysis was to quantify, to the extent
possible, the changes in bathymetry that occurred between
the times of the available surveys.
FOR MORE DETAILED INFORMATION SEE
TILLBATH.TXT
Supplemental_Information:
Renamed from GRID BATH95
FOR MORE DETAILED INFORMATION SEE
TILLBATH.TXT
The variance associated with the 1995 bathymetric
surface was good, in the range of 1 to 2 ft across most of
the bay. This is partly a result of new data collection
techniques that were not available in 1867 and 1957. The
availability of linked global positioning systems (GPS) and
SONAR systems that collect and store x, y, and z
coordinates instantaneously in an on-board computer data
base now permit the collection of tens of thousands
of data points in a fraction of the time required for the
earlier surveys. The variance in this data set could have
been reduced further by collecting data points in a more
regular pattern (equidistant squares or triangles)
rather than along transects.
The range (r) of the semivariogram for 1867 was 584 m, as
compared with 271 m in 1957 and 481 m in 1995 .Other
potential sources of error in the bathymetric maps include
The bathymetric coverages were developed by
interpolating surfaces from the survey data points.
We chose to use ordinary kriging because it is well suited to irregularly spaced data, is custom fit with a geostatistical model, and
allows for calculation of variance associated with the
interpolation. It is a least squares prediction
method that includes a spline interpolation (Jernigan,
1986), and it assumes that the spatial variability in a
surface is statistically homogeneous throughout the data.
Kriging calculates a weighted moving average equation
which estimates the true value of a regionalized variable
and site specific location (Deutsch and Journel 1992,
Cressie 1991).
In order to perform kriging, the spatial correlation
structure of the data needs to be assessed. A variogram
model provides the interpretation of the correlation
structure of the data (Englund and Sparks 1988). This is
determined by representing the correlation among sample
points separated by specific distances (y(h)).
The model was fitted interactively and graphical
examination of the semivariogram assisted in determining a
good model fit (Jernigan 1986). A Gaussian distribution
was chosen to fit the model to the data.
FOR MORE DETAILED INFORMATION SEE
TILLBATH.TXT
Process_Date: Unknown
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Joe Bernert or Tim Sullivan
Contact_Organization: E&S Chemistry
Contact_Address:
Address_Type: Mailing and Physical Address
Address: P.O. Box 609
City: Corvallis
State_or_Province: OR
Postal_Code: 97339
Country: USA
Contact_Voice_Telephone: (541) 758-6305
Contact_Electronic_Mail_Address: unknown
Spatial_Data_Organization_Information:
Direct_Spatial_Reference_Method: Raster
Raster_Object_Information:
Raster_Object_Type: Grid Cell
Row_Count: 1409
Column_Count: 866
Spatial_Reference_Information:
Horizontal_Coordinate_System_Definition:
Planar:
Map_Projection:
Map_Projection_Name: Lambert Conformal Conic
Lambert_Conformal_Conic:
Standard_Parallel: 43
Standard_Parallel: 45.5
Longitude_of_Central_Meridian: -120.5
Latitude_of_Projection_Origin: 41.75
False_Easting: 400000
False_Northing: 0
Planar_Coordinate_Information:
Coordinate_Representation:
Abscissa_Resolution: 30
Ordinate_Resolution: 30
Planar_Distance_Units: 3.2808400000
Geodetic_Model:
Horizontal_Datum_Name: North American Datum of 1983
Ellipsoid_Name: GRS1980
Semi-major_Axis: 6378206.4
Denominator_of_Flattening_Ratio: 294.98
Entity_and_Attribute_Information:
Overview_Description:
Entity_and_Attribute_Overview:
depth VALUE in feet
BATHGRID95.VAT
COLUMN ITEM NAME WIDTH OUTPUT TYPE N.DEC
1 VALUE 4 10 B -
5 COUNT 4 10 B -
Entity_and_Attribute_Detail_Citation: not available
Distribution_Information:
Distributor:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: Tillamook Coastal Watershed Resource Center
Contact_Instructions: Contact via email,mail,fax or telephone
Distribution_Liability:
no warranty expressed or implied is made regarding the accuracy or utility of the data on any other
system or for general or scientific purposes, nor
shall the act of distribution constitute any such
warranty. This disclaimer applies both to
individual use of the data and aggregate use with
other data. It is also strongly recommended that
careful attention be paid to the contents of the
metadata file associated with these data.
The Tillamook Coastal Watershed Resource Center
shall not be held liable for improper or incorrect
use of the data described and/or contained herein.
Metadata_Reference_Information:
Metadata_Date: 19981215
Metadata_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: Tillamook Coastal Watershed Resource Center