| A method for monitoring bedload transport rate using commercial hydrophones is presented. The results of flume experiments comparing acoustic power to video of bedload transport confirm earlier work showing a linear relationship between acoustic power and bedload transport rate. These results also show that acoustic methods have the potential to record changes in transport rate at high temporal resolution. Field experiments, conducted during the May 2005 Trinity River (California) dam release, show that a linear prediction of bedload transport compares well with pressure-difference sampler data, and suggests that acoustic data can be used to fill data-gaps between sampling periods. The field data also suggest that a single calibration relationship can be applied over a month-long snowmelt-type flood event. A computer model of acoustic production is presented, and is used to confirm the linear relationship between transport rate and acoustic power observed in the flume and in previous work. The model also shows that a single hydrophone may be highly sensitive to changes in the cross-stream distribution of bedload transport. |
