抄録
In recent years, the so-called unmanned air vehicles (UAV), remotely controlled airplanes or multicopters, have become available for various civil engineering purposes. In the field of river engineering, although they have been used to investigate the area of vegetation zone or other objectives, measurement of river flow has not been conducted by using an UAV, probably due to the difficulty of image stabilization. In this research, we developed a method to measure river surface velocity distributions by using videotaped images. The specific feature of the method is the introduction of a high-accurate and efficient image stabilization in order to apply the space-time image velocimetry (STIV) to airborne images. The developed method was applied to investigate snowmelt flood of the Uono River, with success of measuring twodimensional velocity distributions for a river reach of about four hundred meters. The obtained results were used to compare with those measured by ADCP or STIV using oblique images from a riverbank.
