288 / 2024-02-29 08:13:20

Development of a practical image-based flowmetric system using CCTV images for small-sized rivers

Image-based Flowmetric system,Surface image velocimeter,Main flow direction,Spatio-temporal image,CCTV,11-parameter projection method

The purpose of this study is to present the most appropriate hardware and software configurations to produce a practical image-based flowmetric system. The term 'practical' means that the system can measure the water level and flow velocity of the river at two minute intervals, which is almost real-time in the actual river, and calculate the flow discharge from the measured data. In addition, it also means that this work is not done once, but continuously at all times. To make a practical flowmetric system, we constructed the system with a CCTV, a ultrasonic water stage gauge, and an analysis software(SIV, surface image velocimeter) on an Android board. The CCTV camera continuously captures images for 30 seconds with 2 minute intervals. And the 11-parameter projection method was used in the software that analyzes the captured images to reconstruct the exact measurement points according to the changing water stage. In addition, a spatio-temporal image construction method was developed so that the directions of the images can be arranged in the main flow direction at each measurement point. The spatio-temporal images were analyzed by using cross-correlation method and fast Fourier transform method to obtain flow velocities. The flowmetric systems composed of the proposed method were produced and installed at small-sized rivers in Korea. And results of measurement of during heavy rainfall events showed that the proposed system could precisely measure flow discharges in a rapid and stable manner.