Estimation of Dam Water Discharge Rate Using Observations of Low-Frequency Acoustic Waves

Weak, sustained infrasound waves associated with natural and environmental sources (e.g., waterfalls, avalanches, dams, and debris flows) can be detected by remote infrasound arrays. Large-volume water flows at waterfalls and dams convert the mechanical energy of flowing water into various forms of energy, including acoustic energy in the infrasound range. Under certain circumstances, infrasound observations of sudden and otherwise unexpected large-scale water flow events can be used for early disaster warning, thereby contributing to disaster mitigation. Beyond early warning, this study investigates whether remote infrasound observations can be used to quantify the intensity of water release (discharge rates) at dams. To establish a relationship between infrasound energy and water discharge at a reference distance of 1 km, data were obtained from controlled water-release events at a dam in South Korea. Since water-release signals observed at regional distances are generally noise-like and exhibit low signal-to-noise ratios, two infrasound detection algorithms, based on the correlation (PMCC) and the maximum likelihood (MCML), were applied, and their detection results were compared to evaluate the performance of each method. Based on the detected infrasound signals at a distance of 15 km from the dam, discharge rates were estimated using the derived empirical relationship. The estimated discharge rates show promising agreement with the actual discharge rates, demonstrating the feasibility of this approach. Overall, our results indicate that infrasound monitoring has practical potential not only for early warning but also for quantifying hazardous water discharge, thereby enhancing disaster monitoring and response capabilities.