Abstract
For establishing non-intrusive techniques for river surface flow measurements, video images shot from riverbank by a river monitoring camera have been paid attention in the past decades and the image analysis techniques such as LSPIV or STIV have been developed. Although these image-based techniques assume that water surface textures are advected with the surface flow, this assumption may fail when the effect to surface waves becomes more predominant. In order to improve the measurement accuracy of STIV, the wavenumber frequency analysis of space-time images were conducted, with success of separating the effect of turbulence-generated ripples moving with the surface flow from those generated by free-surface waves.
