Peer-reviewed articles about the SediMeter™

The SediMeter was recently evaluated by Thomas & Ridd (2004) in "Review of methods to measure short time scale sediment accumulation" (Marine Geology 207:95-114). They wrote: "Finally, amongst continuous methods measuring surface elevation changes, improvements are most likely to stem from increase in vertical resolution and a decrease in prices, assuming that their use becomes more and more widespread" (emphasis added). We agree, and Model 2 of the SediMeter is the proof of it.

We would like to make a couple of comments, though. First, they list the accuracy as unknown. It can be calibrated to 0.1 mm, but if not calibrated it may be estimated to ca 1 mm. Secondly, they claim that one can not tell the difference between erosion and compaction. However, data suggests that it is possible, provided that the resistor Rsense is chosen so that the optical backscatter detectors under the bottom are not saturated. They may then be used to measure the decrease in pore space associated with compaction. Thus, depending on the choice of Rsense one may opt for either high resolution when the sediment concentration is low (such as in the water), or to be able to measure very high "sediment concentrations" (such as from compaction of the accumulated sediments). The instrument is delivered with a standard resistor value that is a compromise between the two interests, but a handy user may exchange them. There are 6 interleaved OBS-circuits so it is also possible to use different values, thereby being able to measure both high and low concentrations with optimal resolution.

The SediMeter™ was originally introduced in the peer-reviewed scientific literature in the following paper:

A Sensor for Measuring Erosion and Deposition

by ERLINGSSON, U.
Journal of Sedimentary Petrology, Vol. 61, Nr. 4, pp. 620-623 (1991)

Introduction

The processes of sediment transport and deposition entail questions of the frequency of transport, the threshold of transport, the migration of bedforms, and the sedimentation and resuspension of sediments carried in suspension. The study of these processes demands the simultaneous monitoring of the process agencies, i.e., the current and the waves, and the response at the sediment-water interface.

In the past, two main approaches have been used to measure changes in bottom elevation in the wave-influenced environment: optical methods, using time-lapse camera or a video-camera (e.g., Davies 1985), and acoustical methods, using a high-frequency echo-sounder mounted at some distance above the bottom (e.g., Wright et al. 1985). However, not even an echo-sounding frequency of 1 MHz can give a resolution better than a few millimeters, which is not always quite adequate (e.g., in areas of low intensity processes, plane bed transport, or when studying ephemeral mud blankets). Both the echosounder and the cameras are quite bulky and will disturb the flow pattern if they are put too close to the point of study. At longer distances the cameras are severely limited by suspended sediments, notably at just those events that are of most interest. Furthermore, video cameras produce an enourmous amount of data that is not readily interpretable by computers.

The present instrument, the "sedimeter" (patented), is also optical in that it uses light as an information-carrier, but due to its operating principle it is not disturbed by suspended sediment or colored water. The disturbance of the flow pattern associated with it is small and rather constant.

The full article is not available online but can be ordered from any research library.