USGS/UH: Beach Profile Data Description

DATA DESCRIPTION

Between August 1994 and July 1999, biannual beach profiles were collected at 42 Oahu and 36 Maui locations. Surveys were conducted at approximately summer-winter intervals. Profile data on this CDROM are presented in both Microsoft EXCEL 97/98 & 5.0/95 Workbook (.xls) format and comma separated value (.csv) format. Graphical representation of the surveys (x vs. z and x vs. y) are presented in EXCEL format only. Site descriptions, including beach location, directions to site, GPS information, and a description of Reference Points used, are available in both EXCEL and ADOBE ACROBAT .pdf format.

Description of EXCEL files:

EXCEL files include four separate data worksheets or charts within the summary file:

SITE_SUMMARY.txt	X,Y,Z data, and Z values converted to Local Tidal Datum (LTD), where available.
Reference Points	Site description and description of reference points used for individual surveys. GPS information included where available.
Profile	Graphic plot of cross-shore beach profile data (LTD Profile where profile converted to the Local Tidal Datum). Z elevations are referenced to the zero (primary RP or LTD) datum. Negative numbers are depths below the zero datum and positive numbers are elevations above the zero datum.
Y-offset	Graphic plot of profile deviation from established profile axis (Deviation from Y)

Description of .csv files:

csv files contain the SITE_SUMMARY.txt data in comma separated value format.

Description of survey data file:

First Row:

Survey date.

Survey time (GMT)

Line number (if applicable)

Second Row:

PT.#	Points with values greater than 900 are permanent profile Reference Points (RPs). Typically, RPs were measured five times and the MEDIAN value recorded in the summary file. RPs were collected both "online" and "offline" in order to determine the position of the profile line. Points with values less than 900 are individual points surveyed along the profile line. Both "online" and "offline" reference points are included in the SITE_SUMMARY.txt file.
X(m)	Distance in meters from the primary reference point.
Y(m)	Distance in meters from the established profile line (Y-offset)
Z(m)	Elevation in meters above or below the primary reference point.
Z(m-LT)	Elevation in meters above or below the Local Tidal Datum.
Difference relative to (GPS survey date)	Deviation in elevation of a common RP relative to the date it was converted to the Local Tidal Datum. Gives an indication of surveying error and/or consistency.
COMMENTS	Includes comments recorded in the field. A list of codes and a schematic profile can be found in the Adobe Acrobat file prof_codes.pdf. Comments in parenthenses () were added for clarity after the fact. Other comments included below the survey data were entered by the author (AG = Ann Gibbs) to describe modifications or problems with the data.

Conversion to Local Tidal Datum:

The local tidal datum is the standard vertical datum used by the National Geodetic Survey (NGS) in the Hawaiian Islands. Surveys collected as part of this study were initially referenced, both horizontally and vertically, to a primary reference point along an individual profile line. Where GPS positions were available, surveys were converted to the local Hawaiian tidal vertical datum. GPS information used to covert the data to LTD are included in the SITE_SUMMARY.txt worksheet.

Volume Change Calculation Boundaries:

Boundaries used to calculate beach profile volume change during the course of the study are also included in SITE_SUMMARY.txt worksheet. X-min is defined by one of the following, depending on local beach morphology and extent of coastal modification: 1) the landward edge of the primary dune; 2) the vegetation line; or 3) the seaward edge of a road, seawall, or other structural feature limiting the natural beach. Z-max is defined by: 1) profile closure where identifiable; 2) the sand/rock interface; and/or 3) the intersection between the sloping shoreface and planar reef platform.

METADATA | OAHU DATA | MAUI DATA | HOME

http://geopubs.usgs.gov/open-file/of01-308/data_description.html
Developed by Ann E. Gibbs
Maintained by Carolyn Donlin
Last modified Sept. 6, 2001
USGS Privacy Statement | Disclaimer | Feedback
Department of the Interior U.S. Geological Survey Geologic Division Western Region Coastal & Marine Geology