Tides 101: What is a Tide Gauge?

A tide gauge, which is one component of a modern water level monitoring station, is fitted with sensors that continuously record the height of the surrounding water level. This data is critical for many coastal activities, including safe navigation, sound engineering, and habitat restoration and preservation.

Before computers were used to record water levels (especially tides), special “tide houses” sheltered permanent tide gauges. Housed inside was the instrumentation—including a well and a mechanical pen-and-ink (analog) recorder—while attached outside was a tide or tidal staff. Essentially a giant measuring stick, the tide staff allowed scientists to manually observe tidal levels and then compare them to readings taken every six minutes by the recorder. Tide houses and the data they recorded required monthly maintenance, when scientists would collect the data tapes and mail them to headquarters for manual processing.

The computer age led to tide gauges that use microprocessor-based technologies to collect sea-level data. While older tide-measuring stations used mechanical floats and recorders, modern monitoring stations use advanced acoustics and electronics. Today’s recorders send an audio signal down a half-inch-wide “sounding tube” and measure the time it takes for the reflected signal to travel back from the water’s surface.

READ MORE at oceanservice.noaa.gov