The SediMeter measures changes in bottom level. One of its uses is to detect sediment accumulation caused by siltation around dredging sites. It can also be used to detect erosion. It is mounted on the bottom, and can either record to its internal memory, or be connected by cable to a separate logger or a PC. There is also a version with a built-in sensor cleaner. The sensor consists of a vertical array of optical backscatter detectors (OBS). The level of the bottom is interpolated based on the turbidity profile, with a precision better than 2 mm over a measurement interval of 35 cm.