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Radio Modem for the SediMeter™

The SediLink™ radio modem is intended to be mounted on a buoy and connected by cable to a SediMeter™ underneath. The solar cells keep the modem and the SediMeter™ charged, and a blinking white LED in each cardinal direction alerts seafarers at night. An XBee radio provides license-free radio communication. There are different frequency and range options available, and many of them also offer meshing. This means that the radios forward traffic, so that the total distance from base station to the farthest radio can be much larger than the range. This allows a dredging operator to monitor siltation, turbidity, or even erosion from the work area in real time.

SediLink

SediLink

Staying clean

SediMeter with built-in cleaner
SediMeter with built-in cleaner

The SediMeter™ SM3B has a built-in cleaner. In many cases the cleaner is not necessary, but in certain cases it definitely helps out in long-time data collection.

The shuttle is hanging in a thin line from a reel on the top of the instrument. At a user-defined interval it is slowly lowered to slightly above the bottom, and pulled up again. A rubber wiper does an effective job at wiping off any incipient biofouling.

Detecting sediment events

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SediMeter SM3A in Biscayne Bay, Florida

The photo shows a SediMeter™ deployed on a tidal channel through the shallow area between Biscayne Bay and the Florida Straits. By measuring the sediment level many times every tidal cycle, and correlating the SediMeter data with tidal data, it became clear what the conditions were for erosion of the channel.

In the science of geomorphology one of the questions have been if the landforms are created by frequency or magnitude. That is, is it the frequent small events, or the rare large-magnitude events that create the landforms? The SediMeter was invented at Uppsala University precisely to answer this question. In this deployment the answer was found successfully.