Sediment Spill Monitoring from Dredging, using the SediMeter2014-10-26
The SediMeter is uniquely suitable for monitoring sediment spill from dredging, or siltation. This document presents various deployment options, suitable for projects of different size budgets and requirements. In applicable parts it is also useful for monitoring erosion.
Getting Baseline Data – The preparatory phase is to collect baseline data. This does not require real-time monitoring, and can be done using a built-in logger. The third generation SediMeter contains 36 near IR optical backscatter detectors in a vertical array, 1 cm apart. Using this turbidity data it calculates the level of the bottom with a precision of a fraction of a millimeter. It also contains a 37th OBS 11 cm above the others, dedicated to turbidity measurements. It can hold 8k measurements.
Increasing Convenience – You can get data without diving if you connect a cable from each SediMeter to a buoy. At regular intervals the user visits the buoy by boat and connects the cable to a laptop computer to download data, and at the same time recharge the internal battery. If the SediMeter is mounted in a frame lowered from the surface, no diving at all is required. This is especially useful in cases where diving is prohibited, dangerous, or exceedingly difficult. The SediMeter without cleaner has the connector in the upper end, while the version with cleaner has the connector in the lower end.
Central Logger – Another option is to connect the instruments to a central logger through a cable. This makes data retrieval faster, just a matter of replacing a memory card. The logger can sit on a buoy, or on shore. The latter can be an alternative where buoys are out of the question due to shipping, ice, etc. A solar panel can keep the batteries charged at all times.
Real-Time Monitoring – The ultimate level is real-time data collection, so that works can be stopped if siltation exceeds some determined level. This can be done by connecting the instruments to land, by cable, radio, or a combination of the two.
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