Repeat Bathymetric Surveys
A bathymetric survey has been repeated on four occassions since 1994 to document changes in the morphology and location of the transverse bars. Utilizing a high-precision differential GPS (Global-Positioning System), the tracklines are run as close as possible to a defined transect, as shown in the figure below. On the research vessel, a PC is connected to the GPS output, so that the current position in relation to the defined transect can be plotted on a monitor in real-time. This allows the boat operator to continually correct the position of the boat, keeping as close to the line as possible.

map showing the locations of the bathymetric survey

This map shows the locations of the bathymetric survey lines (1-10), shown in green. The red lines represent the locations of transverse bars, interpreted from aerial photographs (these lines do not extend the full length of the bars, as they are not visible on photos in deeper water).

 bathymetric plots from the January 1997 survey

This figure shows bathymetric plots from the January 1997 survey. The line numbers correspond to the map above, with line 1 being furthest from shore, and line 10 the closest. Notice that the bars are not apparent in lines 1-3, indicating that they do not extend beyond the nearshore zone.

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