Current Monitoring at Shinnecock Inlet

A 0.5-MHz Side-Looking Acoustic Doppler Profiler (ADP) is presently monitoring currents at Shinnecock Inlet on Long Island in New York. The project features an array of SonTek/YSI instruments, and is a cooperative partnership of the U.S. Army Corps of Engineers, the State of New York, SUNY Stony Brook, and Offshore and Coastal Technologies, Inc.

The ADP is mounted off the east jetty, and was chosen for this job to profile currents into the channel and determine the predominant flow patterns.

The large-diameter transducers in SonTek ADPs produce extremely narrow beams, offering distinct range advantages for horizontal profiling. Additionally, the use of a transducer shading technique minimizes side lobe interference, further increasing the maximum horizontal range of the system.

The graph below shows the actual performance of the side-looking ADP. Note that when the instrument was deployed 1.2 m below the surface, it was able to accurately measure currents out to 50 m. This represents a phenomenal aspect ratio of over 40 (i.e., the SL-ADP achieved a horizontal range that was at least 40 times its distance to the nearer boundary). This suggests that placing the ADP at a depth of just 2-3 m may allow a 0.5-MHz side-looking ADP to achieve its full profiling range of 70 to 110 m.

This graph shows the actual performance of the side-looking ADP at Shinnecock Inlet, New York. Note that the main along-channel flow was reached at a distance of about 20 m from the ADP. What is astonishing here is that the ADP was submerged just 1.2 m below the surface and was able to accurately measure current data out to 50 m!

Live data from the Shinnecock Inlet project can be viewed at http://www.lishore.org/shinnecock/latest.htm.

In addition to the side-looking ADP, the Shinnecock Inlet Field Monitoring Project is also using the following SonTek systems for the listed purpose. The locations of these systems can be found at http://www.offshorecoastal.com/GaugeDescript.htm.

• ADP