Surface flow velocity distributions of flood flows are measured by using a conventional video camera. Surface flow patterns visualized by water surface ripples, foam, drifting wood, or local differences in color of water are analyzed by a specific PIV (Particle Image Velocimetry) technique developedby one of the authors that can treat oblique angled video images. The point of this paper is to check the accuracy of discharge measurements with PIV by comparing it with those obtained by the other velocity measurement techniques such as the float method, the method that uses aerial photographs andthe Manning's formula. In addition, velocity resolution by the PIV measurement is examined in detailas functions of viewing angle and distance from the video camera.
The result shows that estimated discharges by the presented PIV technique are comparable to those obtained by the float method. The PIV technique is a promising method that can farther be extended to an automatic measurement preparingfor the coming optical fiber cable network system.
