What is a SediMeter?
A SediMeter™ sensor measures a vertical turbidity profile and interpolates the bottom level with high resolution
The SediMeter can be used to get quantitative data on the dynamics of the sea floor with high temporal resolution, and it is ideal for monitoring sediment spill from dredging in real-time. It can also be used to monitor what is happening below the bottom, inside the sediment pack, i.e. anoxia and methane bubble formation. Level changes of as little as 0.1 mm can be detected, or the sedimentation of only 100 grams per square meter.
The "color SediMeter", new for 2017, measures both straight and oblique backscatter, giving a false color image with 5 mm resolution. It measures a 35 cm long vertical profile of turbidity at 71 levels using 36 near infrared optical backscatter detectors, 1 cm apart. Brown to beige tones denote buried detectors, while those exposed to air become blue.
SediMeter™ model SM3A mounted in Biscayne Bay.
There is also a dedicated OBS turbidity sensor mounted higher up. The calculated level, along with this turbidity, can be measured as "burst samples", up to 20 times for each measurement, at an interval of between 1 and 16 seconds. Software is included.
Model SM3B has a built-in mechanical cleaner (left). Model SM3A has a diameter of only 15 mm (right). A new model SM3C looks like SM3A but features a vibrator for sensor cleaning without external moving parts. The SediMeter offers several deployment options. The instrument can be used both as a stand-alone logger and connected to a cable.
By measuring turbidity every 5 mm, in two different ways, and presenting the data as a color plot, the ability to discriminate between different targets improves, such as between different grain sizes, between solid bottom and fluid mud, or between wet sand and air (at night; sunlight prevents reliable measurements).
SediLink™ radio modem
A SediLink™ radio and cell phone modem (pdf) can be used to replace cable. It has a recheargeable battery, and a built in solar panel to charge itself and the connected SediMeters. It also has white blinking lights to alert seafarers about the buoy. The SediLink™ has a socket for an X-Bee radio, allowing a choice of inexpensive radio depending on the need for range, and the local regulations. It mounts on top of a tube with the cable through the tube and down to the instruments on the bottom. It can be used anywhere that X-Bee radios are sold: North and South America, Europe, Australia, and so on. In the U.S. it can also be used as a cellular phone modem. Contact us for a quote.
The SediLink™ radio modem mounted on a buoy.