| Flood flows in rivers are generally composed of several different sizes of eddies, such as horizontal large eddies, cellular secondary currents, Kolk-boil vortices, depending on velocity difference. In addition, flood flows in Japanese rivers are characterized by high velocity and high turbidity. Moreover, floating object including driftwood and litter endanger observers. Therefore, only float-type measurements have been conducted in discharge measurement for more than 80 years. Also, it has been considered to be impossible to understand flow characteristics. Recently, painstaking efforts by Dr. Kinoshita in flow measurement using ADCP-mounted, radio-controlled boats have made it possible to obtain 3-D velocity distribution in actual rivers. In this paper, the authors analyzed the measured data using the Fourier series expansion method, and discussed flow characteristics. In addition, the authors discussed the influence of flow characteristics on flow discharge measurement. |
