An initial analysis of two western rivers’ turbulent-flow-induced noise

Abstract

This talk describes noise characteristics near turbulent sections of the Provo and Colorado Rivers in Utah. For reference, these rivers are characterized as medium-sized bedrock rivers, with Strahler orders of 5 and 7, respectively. Larson Davis 831C sound level meters were used to obtain two-second, one-third octave time histories within several meters of the bank at different locations and different times of day. Along the Provo River, the low-frequency content (below 250 Hz) varies with time of day and is likely contaminated by anthropogenic noise sources. The high-frequency noise (above 250 Hz) spectral shape is remarkably similar for every measurement; this spectrum is possibly characteristic of turbulent flow in smaller rivers. However, a measurement near a Colorado River Class III rapid reveals significantly more low-frequency spectral content, but similar high-frequency behavior. Initial efforts to correlate noise with available physical data on both river systems such as flow rates, river depths, river gradient, and terrain composition are described.