Bed-Load Transport Measurements with Geophones and Other Passive Acoustic Methods

This paper reviews the more widely used bed-load surrogate acoustic measuring techniques that were tested both in flume experiments and field settings. A fair number of these measuring techniques have been successfully calibrated for total bed-load flux, which generally requires contemporary direct bed-load transport measurements in the field. Essentially, linear or power-law relations were established between a simple metric characterizing the acoustic signal and bed-load mass. In some studies, further calibration relations were established to identify particle size, either based on signal amplitude and/or on characteristic frequency of that part of the signal associated with a single impact of a particle (e.g., for impact plate systems), or by determining a characteristic frequency for an entire grain-size mixture (for the hydrophone system). A few of the acoustic measuring techniques were used to determine bed-load transport by grain-size classes. Some studies examined how far findings from flume experiments can be quantitatively transferred and applied to field sites for which independent, direct calibration measurements exist. (C) 2017 American Society of Civil Engineers.