Abstract:In order to reduce the staining method of slope flow velocity measurement error, improve the dyeing method of measurement accuracy, according to the characteristics of color change caused by the diffusion of dye tracer in water, a shallow water flow velocity measurement system based on photoelectric sensor technology was developed by combining diffuse reflection analog photoelectric color sensor and data acquisition card to collect signals, and wavelet transform was used to denoise the signal. Taking the discharge method as a reference, the optimal data acquisition distance of the sensor of the system was determined to be 0.6~0.8 m. When the sensor data acquisition distance was 0.7 m, the minimum relative error of the measured data of the system was only 0.48%, and the coefficient of variation was less than 15%. Compared with the dye tracing technique, the fitting coefficient of the system and the discharge method was more than 0.90, which is greater than the dye tracing technique's coefficient of 0.75. The results show that the measuring system is superior to the dye tracing technique and can be used in the experimental study of shallow overland flows.