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

Disaster Prevention Research Institute, Kyoto University, Uji, Japan

^* Corresponding author: koshiba.takahiro.47v@st.kyoto-u.ac.jp

Abstract

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.