Optimal viewing angle and image analysis method for measuring flood discharge of small-sized river using existing CCTV system

Abstract

In this study, a Closed-Circuit TeleVision (CCTV) system, installed for the monitoring purpose, is utilized for measuring flow rate during flood. The procedure to determine both angle and scale-factor of the camera is described. Then, image analysis techniques, namely the marker tracing method and PIV method, are applied to the video images recorded by the camera, and the results by these methods are compared with each other including the conventional float method. In addition, the accuracy of the respective methods are discussed in detail. Finally, a set of low-quality video images, recorded during a flood in thunderstorm occurred under the dark ambient condition (mid-night), is analyzed and transition of flow rate during the event is successfully estimated in detail.