Development and calibration of an underwater acoustic data collection system for monitoring coarse bedload transport

Abstract

Passive acoustic technology has potential as a surrogate method for monitoring coarse bedload transport in rivers and streams. This has been demonstrated by both laboratory experiments and field studies where it was found that acoustic energy generated by particle collisions was proportional to the amount of bedload in transport. One factor that has inhibited further development of the technique is that comparison of acoustic data is complicated by the wide variety of hardware used. A second factor is the need for each research group to assemble hardware, which is often expensive and designed for laboratory use. In addition, the hardware used in the field is rarely calibrated. In order to demonstrate how an entire acoustic data acquisition system should be calibrated for coarse bedload data collection, this manuscript presents the assembly and calibration of an inexpensive acoustic system comprised of readily available equipment. The following are presented here: assembly of the system, key operating parameters and suggested specifications, system calibration, and experiences from multiple deployments of the example system.