Application of the wavelet transform to sediment grain sizes analysis with an impact plate for bedload monitoring in sediment bypass tunnels

An impact plate (IP) is a bedload transport monitoring device developed for a part of the sediment bypass tunnels management. In the measurement, the impact produced by bedload is recorded as the number of impulses (I p ) which is widely used in Japan. I p , however, has several shortcomings attributed to the insufficient raw signal denoising. In this study, the discrete wavelet transform (DWT), an advanced signal processing technique especially for noisy, non-periodical, and transient signals, was introduced to devise an improved I p count system solving the problems in the original signal denoising process. The presented results revealed that the DWT is useful for water noise reduction, signal overlap reduction, and mitigating I p saturation at grain sizes D s = 50 and 100 mm compared to the original I p counting system.