Abstract
Toward developing acoustic monitoring for stream gauging applications, we show the dependence of stream sounds on discharge and morphology in field and lab studies. Currently, there is need for innovative, non‐invasive, and low‐cost methods of surface freshwater discharge monitoring, and recording aerial fluvial sounds could be used inexpensively to infer discharge changes. An important knowledge gap preventing acoustic gauging use is how stream sounds depends on discharge and stream morphology. To address this, we record and characterize sound produced by 8 morphologically diverse fluvial features across multi‐year spans and 2 physical models with controlled discharge and morphology. At field sites, using sound to infer discharge is most reliable at step features with low width/depth (W/D) ratios, and at high W/D step features with channels that show little to no spatiotemporal changes in channel morphology, but is less reliable at riffle features and step features with temporally variable channel morphologies. At several field sites and a discharge variable, constant morphology plunge‐pool, acoustic power increases with flow until a discharge threshold, where it either remains constant or decreases with rising discharge. In a constant discharge plunge‐pool with variable morphology, rising downstream depth strongly influenced both acoustic power and mean frequency. A plunging jet's initial drop height and the width of its receiving pool clearly influenced acoustics, while the width of a jet may also affect acoustics. With more studies in morphologically diverse channels such as bedrock and cascade, acoustics may be used as a non‐invasive, inexpensive, and accurate hydrometric tool to help fill global spatiotemporal discharge monitoring gaps.